text:
A55 road

The A55, also known as the North Wales Expressway (Gwibffordd Gogledd Cymru), is a major road in Wales and England, connecting Cheshire and North Wales. The vast majority of its length from Chester to Holyhead is a dual carriageway primary route, with the exception of the Britannia Bridge over the Menai Strait and several short sections where there are gaps in between the two carriageways. All junctions are grade separated apart from a roundabout east of Penmaenmawr and another nearby in Llanfairfechan. Initially, the road ran from Chester to Bangor. In 2001, it was extended across Anglesey to the ferry port of Holyhead parallel to the A5. The road improvements have been part funded with European money, under the Trans-European Networks programme, as the route is designated part of Euroroute E22 (Holyhead – Leeds – Amsterdam – Hamburg – Malmö – Riga – Moscow – Perm – Ekaterinburg – Ishim).

The Chester southerly bypass
The A55 begins at junction 12 of the M53, the southern end of the motorway, near Chester. It is known as the Chester southerly bypass between J39 Christleton and J36a Broughton. The A55 crosses the River Dee and the border into Wales, passing close to Broughton, Flintshire, and passing north of Buckley, Penyffordd and Northop. There is a major climb between Broughton and Dobshill (Junctions 36a Broughton to 35 Dobshill) though with no crawler lane. Junction 34/33b is point at which the A494 converges and then diverges with the A55. The road briefly has a three-lane section as westbound traffic from Queensferry can leave towards Mold. In the eastbound direction another short three-lane section allows vehicles to join the A494 or exit onto the A55 to Chester. Traffic taking the A55 into England must negotiate a tight 270 degree speed-limited single lane curve to climb up and over the A55/A494 at Ewloe loops. Plans to upgrade the A494 between this junction at Ewloe and Queensferry were rejected by the Welsh Government on 26 March 2008 due to their scale.

Ewloe to Colwyn Bay
From Ewloe, the road is relatively flat until after Northop when it climbs up onto the flanks of Halkyn Mountain range, passing to the southwest of Holywell with major climbs between Northop and Halkyn (Junctions 33 and 32b) and Halkyn and Holywell Summit (Junctions 32 and 31). This section of road is notorious for poor weather conditions including fog, ice and snow in winter months. In fine weather, however there are extensive views over the River Dee estuary to the Wirral Peninsula, Liverpool and beyond. The highest part of the road is in the vicinity of Brynford at around 790 feet (240 m). The steep descent towards St Asaph is down the new Rhuallt Hill (Junctions 29 to 28), which also provides the first views of the mountains of Snowdonia in the far distance. There is a crawler lane on Rhuallt Hill for eastbound traffic. The road bypasses St Asaph to the north, and runs past Bodelwyddan and Abergele to reach the North Wales coast at Pensarn (Junction 23A). From here onwards to Bangor, the route is close to the North Wales Coast railway.

Colwyn Bay Bypass
Two sections between (Junction 23) Llanddulas to (Junction 17) Conwy are signed as a 70 mph (110 km/h) speed limit because they are actually special roads. This is because these sections were built under legislation for building motorways but they were never declared as motorways. Legally it means these two stretches of the A55 are neither part of the national UK motorway network nor trunk roads. As such, the national speed limit does not apply so 70 mph (110 km/h) signs (the maximum speed permitted on UK roads) are used instead. Unlike other sections of the A55 that have National Speed Limit (NSL) signage and are accessible to all motor vehicles, motorway restrictions are enforced on these two stretches of road (therefore no pedestrians, learner drivers, etc.)

A 50 mph (80 km/h) limit remains in force through the Colwyn Bay bypass (Old Colwyn to Mochdre). The restriction was imposed for several reasons. First as a safety precaution because the slip-roads on this stretch are unusually short due to the road's design. Part of it was built on a narrow swathe of land through the town that was once the North Wales coast railway; Colwyn Bay railway station had to be rebuilt and the track bed realigned to complete the underpass as the road used the former railway Goods Yard which was relocated to Llandudno Junction. The former four-track railway was reduced to two more northerly tracks to make space for the road. Secondly, the reduced speed limit was intended to reduce road noise for residents. However, since the completion of the Colwyn Bay bypass, the lower speed limit has been an unpopular decision with drivers.

Conwy Tunnel
The crossing of the estuary of the River Conwy is by means of an immersed tube tunnel, the first of its kind constructed in the United Kingdom. At 1060m, the tunnel is the longest road tunnel in Wales.

The decision to construct an immersed tube tunnel bypass followed an extensive public consultation, named the Collcon Feasibility Study. This ruled out another bridge by the castle on aesthetic grounds, since it would have damaged the view of the world heritage site Conwy Castle, and the two bridges by Robert Stephenson and Thomas Telford. Another alternative bridge crossing was proposed at Deganwy, but this too was ruled out for aesthetic reasons. An inland alternative with heavy grades which would have passed over Bwlch y Ddeufaen pass at 430 m, following the old Roman road, was also worked up but rejected for cost and utility reasons as it would have required a very long crawler lane.

The tunnel was constructed by a Costain/Tarmac Construction joint venture, as pre-formed concrete sections, and then floated into position over a pre-prepared trench in the bed of the estuary. The 3 million tonnes of silt and mud extracted to create the trench in which the tunnel sections sat, were vacuumed to one side of the construction site, as to let them drift down river would have harmed the large mussel fishing beds downstream. The silt was deposited upstream of the bridge at Conwy which created a large new area of low-lying land which was subsequently given to the RSPB for a wildlife preserve. The casting basin for the tunnel sections was later converted into a new marina in the lower estuary. Because of the valuable fishery in the river and also because of the history of heavy metal mining in the catchment of the river, extensive ecological assessments were made both prior to the construction of the tunnel and subsequently. These studies finally concluded that no significant environmental damage had been caused.

After five years of construction, the tunnel was opened in October 1991 by Queen Elizabeth II, the tunnel initially had an advisory 50 mph speed limit, but this was dropped in 2007 as accidents were rare in the tunnels.

Penmaenbach and Pen-y-clip tunnels

Leaving Conwy in a westerly direction, the construction of this section has involved major civil engineering works because it crosses two major headlands: Penmaenbach Point and Penmaenan Point. Work has involved the cutting of several hard rock tunnels beneath the sea cliffs.

The first to be built in 1932 was the Penmaenbach Tunnel which carried motor traffic to Penmaenmawr. Two smaller tunnels through Penmaenan Point, opened 1935, carried the road on to Llanfairfechan. This new route, carrying traffic in both directions, relieved the original coach road built by Telford in the early 19th century. Cut into the cliffs by hand, this narrow, winding route hugged the contours around both steep headlands. Telford's route has now been converted into a cycleway across Penmaenbach and Penmaenan Points. Originally at the western end (Llanfairfechan) of the modern Pen-y-Clip tunnel, access was only allowed in an easterly direction because travelling the other way would mean heading the wrong way up the eastbound carriageway. However, in 2009 a purpose-built bridge – over the westbound carriageway – was constructed to allow unrestricted access to cyclists and walkers.

The 1930s alignment was used until a new two-lane Penmaenbach Tunnel opened in 1989 to carry westbound traffic. Eastbound traffic would now travel through the 1932 Penmaenbach Tunnel using both its original lanes. Four years later, work to build the Pen-y-clip tunnel was completed. Like at Penmaenbach it carried westbound traffic while the original road carried vehicles in the opposite direction. Both new routes were subject to an advisory 50 mph speed limit until these were lifted in 2007 as there had been few accidents.

However traffic travelling eastbound on the 1930s cliff-hugging route still faced speed restrictions at both tunnel locations. For instance the eastbound carriageway at Penmaenbach is subject to a 30 mph (50 km/h) speed limit due to sharp curves and double white lines nominally preclude lane changing. Plans to rectify the awkward alignment by building another tunnel parallel to the current westbound tunnel (as originally intended when the westbound tunnel was proposed) have been discussed for several years. The work in late-2007 at Penmaenbach eastbound has seen the erection of gantries to close lanes when bidirectional working is in place. New bridges over the railway tunnel entrances at each end were added and a footbridge over the railway at the eastern end to accommodate the cycleway.

Penmaenmawr to Anglesey
Some sections of the rest of the route are of lower standard than that of those further east. Some traffic leaves for major holiday destinations such as Caernarfon or the Llŷn Peninsula, though much continues on to the port of Holyhead. As such part of the route is not classed as clearway and has two at grade junctions (roundabouts), Penmaenmawr (Junction 16) and Llanfairfechan (Junction 15). The Bangor bypass, in which the road previously terminated and became the A5 regains high standards and is such through the Anglesey section, bar the Britannia Bridge, which is a single carriageway deck above the North Wales Coast railway over the Menai Strait. In 2007 the Welsh Assembly Government undertook a consultation to determine which of four options would be preferred for another crossing. This section intersects with the A487 towards Caernarfon, and the west coast of North Wales.

Anglesey
The final section of the A55 to be constructed was the Anglesey section. This 20 mile (32 km) section from the end of the Llanfairpwll bypass to Holyhead Harbour was constructed as Private Finance Initiative scheme where the builders, a Carillion / John Laing joint venture, earn a shadow toll based on usage and lane availability. They also have to maintain the road for the extended period of their shadow toll agreement. When travelling eastbound along this section there are fine views of Snowdonia. The approach to Holyhead required major work with a new section over the sea paralleling the Stanley Embankment that carries the original A5 and the North Wales Coast railway.

Improvements underway
Work started in early 2017 on the upgrading of the 1960s built substandard section of dual carriageway west of Abergwyngregyn from Tai'r Meibion towards Tan-y-lon, which is a relatively narrow section of dual carriageway and prone to flooding. After a pause, work restarted on the scheme (now known as the Abergwyngregyn-Tai'r Meibion scheme) in 2021 and encompassing some 2.2 km of the A55. It involves constructing a new road to the north of the dual carriageway for general use including cycleway and farm access. This allowed the closure of 8 central reservation gaps used by slow moving agricultural vehicles which caused safety concerns with the volume and speed of traffic on the dual carriageway. The work was well underway in September 2021 and due to open fully in 2022.

Planned improvements
Plans are also in their final stages to grade separate the two roundabouts at Penmaenmawr and Llanfairfechan planned to be completed by 2022. A Public Inquiry was due to be held on 21/9/21 in Llandudno Junction concerning issues over the side roads. The two roundabout improvements will now be treated separately and the full plans can be seen on the A55 microsite. In June 2021 the Welsh Government decided to review all road schemes whilst looking at public transport alternatives. In September 2021 the Welsh Government announced an expansion of their plans for the North Wales Metro that may impact this road scheme. In particular longer term plans to reopen old rail routes from Bangor to Amlwch and Bangor to West Wales (presumably a link to Cambrian Coast railway and possibly onwards from Aberystwyth to Carmarthen) may impact cash available for road schemes. The Junction 16 scheme involves creating a new grade separated junction close to the Penmaenbach Tunnel with a single overbridge allowing access for all directions. This will replace the limited access junction 16A there for Dwygyfylchi. The existing junction 16 roundabout would be replaced by a limited access junction (westbound off/westbound on) as it is a difficult location close to the North Wales coast railway and cycle route and partly on a railway bridge. A new local road would run from the new Dwygyfylchi interchange to the existing roundabout passing around the rear of the Penguin Cafe/truckstop. The Llanfairfechan junction 15 grade separation is much easier to achieve and will be completed on site as a grade separated junction with a single overbridge allowing access/exit for all possible directions.

In November 2012, the Welsh Government published two more detailed studies looking at options to improve transport in the North East Wales and the A55 / A494 areas. Possible changes to be considered further include
 * applying managed motorway concepts
 * providing hard shoulders
 * providing crawler lanes at key points
 * redesigning and improving slip roads.

History
The A55 partly follows the alignment of the Roman road from Chester (Deva) to Caernarfon (Segontium), particularly from Junction 31 to 30 and Junction 13 to 12. Between Chester and Holywell the alignment of this road is uncertain and between St. Asaph and Abergwyngregyn, the Roman road followed an inland route, via Canovium Roman Fort at Caerhun, avoiding the difficulties of the crossing of the Conwy estuary and the cliffs at Penmaenbach and Pen-y-Clip.

1930s

 * Unknown date pre1832 Ewloe to Northop avoiding Northop Hall (shown of OS surveyor's 1832 hand-drawn survey map in Flintshire Archives)
 * 1931 or 1932 Northop Bypass
 * Summer 1932 Holywell Bypass
 * Unknown date 1930s? St. Asaph to Rhuallt dual carriageway and roundabouts
 * Unknown date 1930s? Short section of 'experimental' concrete road west of St Asaph
 * 1932 Penmaenbach Tunnel
 * 1935 Pen-y-Clip Tunnels
 * Post 1938 Vicar's Cross: A41/A51 interchange. (Directly over the site of Vicar's Cross, a mansion in occupation 1938 – Folliott family-this only became the A55 on completion of the Chester southerly bypass in 1976).

1950s

 * 1958 Conwy new bridge avoiding Telford's suspension bridge opened 13 December 1958. This also included a one way system through Conwy with a new route for eastbound traffic around the town's north wall, eliminating a traffic lights at the town's narrow north gate. Originally it had been intended to go along the quay to the new bridge but this would have destroyed the harbour fishing industry.

1960s

 * 1960s Tai'r Meibion to Tan-y-lon dual carriageway east of Bangor
 * 1964? Ewloe roundabout (part of the A494 Queensferry to Ewloe dualling, the 'Aston Bypass')
 * Unknown date 1965? Llysfaen dualling
 * 1968 Abergele Bypass

1970s

 * 1970 St. Asaph Bypass
 * 1975 Northop Hall Crossroads to East of Gables
 * 1976 Coed-y-Cra to Chaingates (Holywell)
 * 1976 Chester Southerly Bypass (terminating at Broughton with a single carriageway section for the final mile as this was planned to be superseded by the Hawarden Bypass on a more southerly alignment)

1980s

 * 1980 Britannia Bridge and link roads
 * December 1980 Holywell By-Pass (Stage 1)
 * March 1981 Diversion East of Abergele
 * December 1983 Bangor By-Pass
 * September 1984 Hawarden By-Pass (from a point east of Broughton on the Chester Southerly Bypass to Northop Hall)
 * December 1984 Llanddulas to Glan Conwy (Colwyn Bay By-Pass, Stage 1)
 * June 1985 Llanddulas to Glan Conwy (Colwyn Bay By-Pass, Stage 2)
 * October 1986 Holywell By-Pass (Stage 2)
 * December 1986 Bodelwyddan By-Pass
 * June 1989 Penmaenbach Tunnel
 * June 1989 Northop By-Pass (Northop Hall to Halkyn)
 * October 1989 Penmaenmawr and Llanfairfechan By-Passes (excluding Pen-y-Clip Tunnel)

1990s

 * May 1990 Travellers' Inn Improvement
 * June 1991 Extension of Chester Bypass to M53 (Junction 12)
 * 25 October 1991 Tunnel crossing of the River Conwy
 * May 1992 Rhuallt Hill Improvement
 * October 1993 Pen-y-Clip Tunnel
 * October 1994 Abergwyngregyn Improvement

2000s

 * 16 March 2001 Anglesey section (Llanfairpwll to Holyhead) including Llanfairpwll by-pass
 * 2000/2004 Penmaenmawr eastbound slip road and grade separation at the summit of the Rhuallt Hill
 * 2004 Improvements to railway underbridges and cliffs at Penmaenbach (eastbound)
 * 2007 Alterations to roundabout at Llanfairfechan and bidirectional road indicators at Penmaenbach (eastbound)
 * 2008 New overbridge between Junction 32A and 32B for improved local access

Services
There are three large service areas on the A55, along with numerous other petrol stations at the side of the road. The three major services are:

Bangor Services (off J11) This service area is 200m off A55 via A5 southbound then turn right at roundabout onto A4244 before immediately turning right into services) – Starbucks, Subway, Greggs, Burger King, Travelodge, Esso, Costa Express

Gateway Services, Ewloe Eastbound (After J33) – Starbucks, Greggs, Travelodge, Shell, Costa Express Westbound (After J33B) – Costa Coffee, Subway, McDonald's, OK Diner, Holiday Inn, Shell, Costa Express, Deli2Go

Kinmel Park, St Asaph Eastbound (After J24) – Esso, Starbucks & Greggs

Westbound (After J25) – Esso, Starbucks & Greggs

Junctions
{| class="plainrowheaders wikitable" !scope=col|County !scope=col|Location !scope=col|Miles !scope=col|km !scope=col|Junction !scope=col|Destinations !scope=col|Notes Kingsland Bodedern - Llangefni - Bangor, Betws-y-Coed Trefnant - Prestatyn B5112 - Caerwys Northop Hall - Chester - Chester, Helsby
 * rowspan="13"|Isle of Anglesey
 * rowspan="5"|Holyhead
 * 0.0
 * 0.0
 * Holyhead railway station, Holyhead ferry port, Fish quay, Park and ride, Long stay
 * Roundabout
 * Local traffic
 * Traffic lights, TOTSO
 * 0.3
 * 0.5
 * - Town centre
 * Traffic lights, TOTSO
 * 0.4
 * 0.7
 * 1
 * - Trearddur Bay
 * 0.5
 * - Town centre
 * Traffic lights, TOTSO
 * 0.4
 * 0.7
 * 1
 * - Trearddur Bay
 * 1
 * - Trearddur Bay
 * Terminus of the North Wales Expressway, Roundabout
 * 0.7 1.2
 * 1.2 2.0
 * 2
 * - Trearddur Bay Parc Cybi
 * Valley
 * 4.4 4.8
 * 7.1 7.7
 * 3
 * - Valley, Caergeiliog
 * Llanfihangel yn Nhowyn
 * 6.0 6.3
 * 9.6 10.2
 * 4
 * - Caergeiliog, Bryngwran
 * Llanfihangel yn Nhowyn
 * 6.0 6.3
 * 9.6 10.2
 * 4
 * - Caergeiliog, Bryngwran
 * Bryngwran
 * 8.7 9.1
 * 14.0 14.6
 * 5
 * - Rhosneigr, Aberffraw
 * Llangefni
 * 14.4 14.9
 * 23.2 24.0
 * 6
 * - Rhostrehwfa, Pentre Berw
 * 14.4 14.9
 * 23.2 24.0
 * 6
 * - Rhostrehwfa, Pentre Berw
 * Gaerwen
 * 17.3 17.8
 * 27.8 28.6
 * 7
 * - Gaerwen, Pentre Berw, Llanfair Pwllgwyngyll
 * rowspan="3"|Llanfair Pwllgwyngyll
 * 19.4
 * 31.3
 * bgcolor=ffdddd|7a
 * bgcolor=ffdddd| - Llanfair Pwllgwyngyll Star
 * bgcolor=ffdddd|No access to A55 Westbound, no access to or exit from A55 Eastbound
 * 20.4 20.8
 * 32.9 33.4
 * 8
 * - Benllech, Menai Bridge, Amlwch
 * 21.0
 * 33.8
 * bgcolor=ffdddd|8a
 * bgcolor=ffdddd| - Llanfair Pwllgwyngyll, Menai Bridge, Beaumaris
 * bgcolor=ffdddd|No access to A55 Westbound, no exit from A55 Eastbound
 * rowspan="6"|Gwynedd
 * rowspan="3"|Bangor
 * 21.9 22.1
 * 35.3 35.6
 * 9
 * - Bangor, Caernarfon
 * 22.6 23.0
 * 36.4 37.0
 * 10
 * - Bangor
 * 25.0 25.4
 * 40.3 40.9
 * 11
 * Bangor services
 * 22.6 23.0
 * 36.4 37.0
 * 10
 * - Bangor
 * 25.0 25.4
 * 40.3 40.9
 * 11
 * Bangor services
 * 25.0 25.4
 * 40.3 40.9
 * 11
 * Bangor services
 * Tal-y-bont
 * 27.1 27.5
 * 43.6 44.2
 * 12
 * Tal-y-bont
 * Abergwyngregyn
 * 29.3 29.5
 * 47.2 47.5
 * 13
 * Abergwyngregyn
 * rowspan="2"|Llanfairfechan
 * 30.4 30.6
 * 48.9 49.2
 * 14
 * rowspan="2"|Llanfairfechan
 * rowspan="16"|Conwy
 * 32.1
 * 51.7
 * 15
 * Roundabout
 * rowspan="2"|Penmaenmawr
 * 33.4 33.7
 * 53.8 54.2
 * bgcolor=ffdddd|15a
 * bgcolor=ffdddd|Penmaenmawr
 * bgcolor=ffdddd|No access to A55 Eastbound, no exit from A55 Westbound
 * 34.9
 * 56.2
 * 16
 * Penmaenmawr, Dwygyfylchi
 * Roundabout
 * rowspan="2"|Dwygyfylchi
 * colspan="2"|Services
 * 35.9
 * 57.8
 * bgcolor=ffdddd|16a
 * bgcolor=ffdddd|Dwygyfylchi
 * bgcolor=ffdddd|No access to or exit from A55 Eastbound
 * Conwy
 * 37.5 37.9
 * 60.4 61.0
 * 17
 * - Conwy
 * Terminus of special road
 * rowspan="2"|Llandudno Junction
 * 39.5 39.9
 * 63.6 64.2
 * 18
 * - Deganwy, Llandudno Junction
 * 40.3 40.7
 * 64.8 65.5
 * 19
 * - Betws-y-Coed, Llandudno
 * Rhos-on-Sea-Colwyn Bay boundary
 * 42.7 43.4
 * 68.7 69.8
 * 20
 * - Rhos-on-Sea
 * Colwyn Bay
 * 43.9 44.1
 * 70.6 71.0
 * 21
 * - Colwyn Bay
 * Old Colwyn
 * 44.4 44.7
 * 71.5 72.0
 * 22
 * Old Colwyn
 * rowspan="2"|Llanddulas
 * 47.2 47.3
 * 76.0 76.1
 * 23
 * - Llandulas
 * Terminus of special road
 * colspan="2"|Services
 * Pensarn
 * 49.7 50.0
 * 80.0 80.4
 * bgcolor=ffdddd|23a
 * bgcolor=ffdddd| - Pensarn, Rhyl
 * bgcolor=ffdddd|No access to A55 Eastbound, no exit from A55 Westbound
 * Abergele
 * 50.5 50.9
 * 81.2 81.9
 * 24
 * - Abergele, Rhuddlan, Prestatyn
 * St George
 * 52.6
 * 84.6
 * bgcolor=ffdddd|24a
 * bgcolor=ffdddd|Towyn, St George
 * bgcolor=ffdddd|No access to A55 Westbound, no access to or exit from A55 Eastbound
 * rowspan="7"|Denbighshire
 * rowspan="2"|Bodelwyddan
 * Services
 * Kinmel Park services
 * 53.7
 * 86.4
 * 25
 * Bodelwyddan, Glan Clwyd Hospital
 * rowspan="3"|St Asaph
 * 54.8 55.2
 * 88.2 88.8
 * 26
 * St Asaph Business Park
 * 55.9 56.3
 * 89.9 90.6
 * 27
 * - St Asaph, Rhyl
 * 56.9
 * 91.6
 * bgcolor=ffdddd|27a
 * bgcolor=ffdddd| - Denbigh
 * bgcolor=ffdddd|No access to or exit from A55 Westbound
 * rowspan="2"|Rhuallt
 * 57.2 57.9
 * 92.9 93.2
 * 28
 * - Rhuallt, Tremeirchion
 * St George
 * 52.6
 * 84.6
 * bgcolor=ffdddd|24a
 * bgcolor=ffdddd|Towyn, St George
 * bgcolor=ffdddd|No access to A55 Westbound, no access to or exit from A55 Eastbound
 * rowspan="7"|Denbighshire
 * rowspan="2"|Bodelwyddan
 * Services
 * Kinmel Park services
 * 53.7
 * 86.4
 * 25
 * Bodelwyddan, Glan Clwyd Hospital
 * rowspan="3"|St Asaph
 * 54.8 55.2
 * 88.2 88.8
 * 26
 * St Asaph Business Park
 * 55.9 56.3
 * 89.9 90.6
 * 27
 * - St Asaph, Rhyl
 * 56.9
 * 91.6
 * bgcolor=ffdddd|27a
 * bgcolor=ffdddd| - Denbigh
 * bgcolor=ffdddd|No access to or exit from A55 Westbound
 * rowspan="2"|Rhuallt
 * 57.2 57.9
 * 92.9 93.2
 * 28
 * - Rhuallt, Tremeirchion
 * - St Asaph, Rhyl
 * 56.9
 * 91.6
 * bgcolor=ffdddd|27a
 * bgcolor=ffdddd| - Denbigh
 * bgcolor=ffdddd|No access to or exit from A55 Westbound
 * rowspan="2"|Rhuallt
 * 57.2 57.9
 * 92.9 93.2
 * 28
 * - Rhuallt, Tremeirchion
 * 92.9 93.2
 * 28
 * - Rhuallt, Tremeirchion
 * 60.1 60.5
 * 96.7 97.3
 * 29
 * - Rhuallt, Tremeirchion
 * rowspan="13"|Flintshire
 * rowspan="2"|Lloc
 * 61.5 61.7
 * 99.0 99.3
 * 30
 * Tremeirchion
 * 62.3 62.6
 * 100.3 100.8
 * 31
 * - Holywell
 * 62.3 62.6
 * 100.3 100.8
 * 31
 * - Holywell
 * 31
 * - Holywell
 * rowspan="2"|Pentre Halkyn
 * 67.5 67.6
 * 108.7 108.8
 * bgcolor=ffdddd|32
 * bgcolor=ffdddd| - Holywell
 * bgcolor=ffdddd|No access to A55 Eastbound, no exit from A55 Westbound
 * 67.9 68.3
 * 109.3 109.9
 * bgcolor=ffdddd|32a
 * bgcolor=ffdddd| - Rhosesmor
 * bgcolor=ffdddd|No access to A55 Westbound
 * Halkyn
 * 69.2
 * 111.3 111.4
 * bgcolor=ffdddd|32b
 * bgcolor=ffdddd|Pentre Halkyn, Rhosesmor
 * bgcolor=ffdddd|No access to or exit from A55 Westbound
 * Northop
 * 71.2 71.6
 * 114.6 115.3
 * 33
 * - Flint, Mold
 * rowspan="2"|Northop Hall
 * 72.4
 * 116.5
 * 33a
 * - Connah's Quay
 * rowspan="2"|Northop Hall
 * 72.4
 * 116.5
 * 33a
 * - Connah's Quay
 * 33a
 * - Connah's Quay
 * Services
 * Gateway services
 * rowspan="2"|Ewloe
 * 74.6
 * 120.0
 * bgcolor=ffdddd|33b
 * bgcolor=ffdddd| - Mold
 * bgcolor=ffdddd|No access to A55 Westbound, no exit from A55 Eastbound. Terminus of concurrency with A494
 * 74.9 75.2
 * 120.5 121.1
 * 34
 * - Queensferry
 * Terminus of concurrency with A494, TOTSO
 * Buckley
 * 76.5 76.8
 * 123.1 123.6
 * 35
 * - Buckley, Wrexham
 * Broughton
 * 77.9 78.2
 * 125.3 125.9
 * 36
 * - Pen-y-ffordd, Broughton
 * Bretton
 * 79.8
 * 128.5
 * bgcolor=ffdddd|37
 * bgcolor=ffdddd|Broughton
 * bgcolor=ffdddd|No exit from A55 Eastbound, no access to A55 Westbound
 * rowspan="4"|Cheshire
 * rowspan="4"|Chester
 * 38
 * - Wrexham, Chester
 * bgcolor=ffdddd|39
 * bgcolor=ffdddd| - Whitchurch
 * Bretton
 * 79.8
 * 128.5
 * bgcolor=ffdddd|37
 * bgcolor=ffdddd|Broughton
 * bgcolor=ffdddd|No exit from A55 Eastbound, no access to A55 Westbound
 * rowspan="4"|Cheshire
 * rowspan="4"|Chester
 * 38
 * - Wrexham, Chester
 * bgcolor=ffdddd|39
 * bgcolor=ffdddd| - Whitchurch
 * - Wrexham, Chester
 * bgcolor=ffdddd|39
 * bgcolor=ffdddd| - Whitchurch
 * bgcolor=ffdddd|39
 * bgcolor=ffdddd| - Whitchurch
 * bgcolor=ffdddd|39
 * bgcolor=ffdddd| - Whitchurch
 * bgcolor=ffdddd|No access to A55 Northbound, no exit from A55 Southbound
 * 40
 * - Chester, Nantwich
 * - Ellesmere Port
 * 40
 * - Chester, Nantwich
 * - Ellesmere Port
 * - Ellesmere Port
 * - Ellesmere Port
 * - Ellesmere Port
 * - Ellesmere Port
 * - Ellesmere Port
 * Road continues as M53 towards Ellesmere Port

 * Notes
 * Data from location marker posts are used to provide distance and carriageway identification information. Where a junction spans several hundred metres and the data is available, both the start and finish values for the junction are shown.
 * Coordinate data from ACME mapper

 * Coordinate list

title: A55 road


text:
A55

A55 may refer to:

Roads

 * A55 highway (Australia), a road connecting St George, Queensland and Lithgow, New South Wales
 * A55 motorway (Canada), a road in Québec connecting Stanstead and Shawinigan
 * A55 motorway (France), a road connecting Marseille and Martigues
 * A55 road (Great Britain), a road connecting Chester and Holyhead
 * Autostrada A55 (Italy), a bypass around Turin
 * A55 road (Northern Ireland), a road around Belfast

Electronics

 * A-series light bulb of diameter 55 mm
 * a model of a Fusion Controller Hub (FCH), a chipset used for AMD microprocessors
 * Sony Alpha 55, a DSLT camera
 * Siemens A55, a mobile phone
 * ARM Cortex-A55, a processor microarchitecture

Other

 * Old Indian Defense, Encyclopaedia of Chess Openings code
 * Austin Cambridge A55, a British car
 * GER Class A55, a British steam locomotive

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: A55


text:
Rotational spectroscopy

Rotational spectroscopy is concerned with the measurement of the energies of transitions between quantized rotational states of molecules in the gas phase. The rotational spectrum (power spectral density vs. rotational frequency) of polar molecules can be measured in absorption or emission by microwave spectroscopy or by far infrared spectroscopy. The rotational spectra of non-polar molecules cannot be observed by those methods, but can be observed and measured by Raman spectroscopy. Rotational spectroscopy is sometimes referred to as pure rotational spectroscopy to distinguish it from rotational-vibrational spectroscopy where changes in rotational energy occur together with changes in vibrational energy, and also from ro-vibronic spectroscopy (or just vibronic spectroscopy) where rotational, vibrational and electronic energy changes occur simultaneously.

For rotational spectroscopy, molecules are classified according to symmetry into spherical tops, linear molecules, and symmetric tops; analytical expressions can be derived for the rotational energy terms of these molecules. Analytical expressions can be derived for the fourth category, asymmetric top, for rotational levels up to J=3, but higher energy levels need to be determined using numerical methods. The rotational energies are derived theoretically by considering the molecules to be rigid rotors and then applying extra terms to account for centrifugal distortion, fine structure, hyperfine structure and Coriolis coupling. Fitting the spectra to the theoretical expressions gives numerical values of the angular moments of inertia from which very precise values of molecular bond lengths and angles can be derived in favorable cases. In the presence of an electrostatic field there is Stark splitting which allows molecular electric dipole moments to be determined.

An important application of rotational spectroscopy is in exploration of the chemical composition of the interstellar medium using radio telescopes.

Applications
Rotational spectroscopy has primarily been used to investigate fundamental aspects of molecular physics. It is a uniquely precise tool for the determination of molecular structure in gas-phase molecules. It can be used to establish barriers to internal rotation such as that associated with the rotation of the group relative to the  group in chlorotoluene. When fine or hyperfine structure can be observed, the technique also provides information on the electronic structures of molecules. Much of current understanding of the nature of weak molecular interactions such as van der Waals, hydrogen and halogen bonds has been established through rotational spectroscopy. In connection with radio astronomy, the technique has a key role in exploration of the chemical composition of the interstellar medium. Microwave transitions are measured in the laboratory and matched to emissions from the interstellar medium using a radio telescope. was the first stable polyatomic molecule to be identified in the interstellar medium. The measurement of chlorine monoxide is important for atmospheric chemistry. Current projects in astrochemistry involve both laboratory microwave spectroscopy and observations made using modern radiotelescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA).

Overview
A molecule in the gas phase is free to rotate relative to a set of mutually orthogonal axes of fixed orientation in space, centered on the center of mass of the molecule. Free rotation is not possible for molecules in liquid or solid phases due to the presence of intermolecular forces. Rotation about each unique axis is associated with a set of quantized energy levels dependent on the moment of inertia about that axis and a quantum number. Thus, for linear molecules the energy levels are described by a single moment of inertia and a single quantum number, $$J$$, which defines the magnitude of the rotational angular momentum.

For nonlinear molecules which are symmetric rotors (or symmetric tops - see next section), there are two moments of inertia and the energy also depends on a second rotational quantum number, $$K$$, which defines the vector component of rotational angular momentum along the principal symmetry axis. Analysis of spectroscopic data with the expressions detailed below results in quantitative determination of the value(s) of the moment(s) of inertia. From these precise values of the molecular structure and dimensions may be obtained.

For a linear molecule, analysis of the rotational spectrum provides values for the rotational constant and the moment of inertia of the molecule, and, knowing the atomic masses, can be used to determine the bond length directly. For diatomic molecules this process is straightforward. For linear molecules with more than two atoms it is necessary to measure the spectra of two or more isotopologues, such as 16O12C32S and 16O12C34S. This allows a set of simultaneous equations to be set up and solved for the bond lengths). A bond length obtained in this way is slightly different from the equilibrium bond length. This is because there is zero-point energy in the vibrational ground state, to which the rotational states refer, whereas the equilibrium bond length is at the minimum in the potential energy curve. The relation between the rotational constants is given by
 * $$B_v = B - \alpha\left(v + \frac{1}{2}\right)$$

where v is a vibrational quantum number and α is a vibration-rotation interaction constant which can be calculated if the B values for two different vibrational states can be found.

For other molecules, if the spectra can be resolved and individual transitions assigned both bond lengths and bond angles can be deduced. When this is not possible, as with most asymmetric tops, all that can be done is to fit the spectra to three moments of inertia calculated from an assumed molecular structure. By varying the molecular structure the fit can be improved, giving a qualitative estimate of the structure. Isotopic substitution is invaluable when using this approach to the determination of molecular structure.

Classification of molecular rotors
In quantum mechanics the free rotation of a molecule is quantized, so that the rotational energy and the angular momentum can take only certain fixed values, which are related simply to the moment of inertia, $$ I $$, of the molecule. For any molecule, there are three moments of inertia: $$I_A$$, $$I_B$$ and $$I_C$$ about three mutually orthogonal axes A, B, and C with the origin at the center of mass of the system. The general convention, used in this article, is to define the axes such that $$I_A \leq I_B \leq I_C$$, with axis $$A$$ corresponding to the smallest moment of inertia. Some authors, however, define the $$A$$ axis as the molecular rotation axis of highest order.

The particular pattern of energy levels (and, hence, of transitions in the rotational spectrum) for a molecule is determined by its symmetry. A convenient way to look at the molecules is to divide them into four different classes, based on the symmetry of their structure. These are

Spherical tops (spherical rotors):All three moments of inertia are equal to each other: $I_A = I_B = I_C$. Examples of spherical tops include phosphorus tetramer, carbon tetrachloride and other tetrahalides, methane, silane, , sulfur hexafluoride and other hexahalides. The molecules all belong to the cubic point groups Td or Oh. Linear molecules:For a linear molecule the moments of inertia are related by $I_A \ll I_B = I_C $. For most purposes, $I_A$ can be taken to be zero. Examples of linear molecules include dioxygen, dinitrogen, carbon monoxide (CO), hydroxy radical (OH), carbon dioxide (CO2), hydrogen cyanide (HCN), carbonyl sulfide (OCS), acetylene (ethyne (HC≡CH) and dihaloethynes. These molecules belong to the point groups C∞v or D∞h. Symmetric tops (symmetric rotors):A symmetric top is a molecule in which two moments of inertia are the same, $I_A = I_B$ or $I_B = I_C$. By definition a symmetric top must have a 3-fold or higher order rotation axis. As a matter of convenience, spectroscopists divide molecules into two classes of symmetric tops, Oblate symmetric tops (saucer or disc shaped) with $I_A = I_B < I_C$ and Prolate symmetric tops (rugby football, or cigar shaped) with $I_A < I_B = I_C $. The spectra look rather different, and are instantly recognizable. Examples of symmetric tops include
 * Oblate: Benzene, ; ammonia, ; xenon tetrafluoride,
 * Prolate: Chloromethane,, propyne,

As a detailed example, ammonia has a moment of inertia about the 3-fold rotation axis, and moments about any axis perpendicular to the C3 axis. Since the unique moment of inertia is larger than the other two, the molecule is an oblate symmetric top. Asymmetric tops (asymmetric rotors):The three moments of inertia have different values. Examples of small molecules that are asymmetric tops include water, and nitrogen dioxide, whose symmetry axis of highest order is a 2-fold rotation axis. Most large molecules are asymmetric tops.

Microwave and far-infrared spectra
Transitions between rotational states can be observed in molecules with a permanent electric dipole moment. A consequence of this rule is that no microwave spectrum can be observed for centrosymmetric linear molecules such as (dinitrogen) or HCCH (ethyne), which are non-polar. Tetrahedral molecules such as (methane), which have both a zero dipole moment and isotropic polarizability, would not have a pure rotation spectrum but for the effect of centrifugal distortion; when the molecule rotates about a 3-fold symmetry axis a small dipole moment is created, allowing a weak rotation spectrum to be observed by microwave spectroscopy.

With symmetric tops, the selection rule for electric-dipole-allowed pure rotation transitions is,. Since these transitions are due to absorption (or emission) of a single photon with a spin of one, conservation of angular momentum implies that the molecular angular momentum can change by at most one unit. Moreover, the quantum number K is limited to have values between and including +J to -J.

Raman spectra
For Raman spectra the molecules undergo transitions in which an incident photon is absorbed and another scattered photon is emitted. The general selection rule for such a transition to be allowed is that the molecular polarizability must be anisotropic, which means that it is not the same in all directions. Polarizability is a 3-dimensional tensor that can be represented as an ellipsoid. The polarizability ellipsoid of spherical top molecules is in fact spherical so those molecules show no rotational Raman spectrum. For all other molecules both Stokes and anti-Stokes lines can be observed and they have similar intensities due to the fact that many rotational states are thermally populated. The selection rule for linear molecules is ΔJ = 0, ±2. The reason for the values ±2 is that the polarizability returns to the same value twice during a rotation. The value ΔJ = 0 does not correspond to a molecular transition but rather to Rayleigh scattering in which the incident photon merely changes direction.

The selection rule for symmetric top molecules is
 * ΔK = 0
 * If K = 0, then ΔJ = ±2
 * If K ≠ 0, then ΔJ = 0, ±1, ±2

Transitions with ΔJ = +1 are said to belong to the R series, whereas transitions with belong to an S series. Since Raman transitions involve two photons, it is possible for the molecular angular momentum to change by two units.

Units
The units used for rotational constants depend on the type of measurement. With infrared spectra in the wavenumber scale ($$\tilde \nu$$), the unit is usually the inverse centimeter, written as cm−1, which is literally the number of waves in one centimeter, or the reciprocal of the wavelength in centimeters ($$\tilde\nu = 1 / \lambda$$). On the other hand, for microwave spectra in the frequency scale ($$\nu$$), the unit is usually the gigahertz. The relationship between these two units is derived from the expression
 * $$ \nu \cdot \lambda = c,$$

where ν is a frequency, λ is a wavelength and c is the velocity of light. It follows that

\tilde \nu / \text{cm}^{-1} = \frac{1}{\lambda / \text{cm}} = \frac{\nu / \text{s}^{-1}}{c / \left(\text{cm} \cdot \mathrm{s}^{-1}\right)} = \frac{\nu / \text{s}^{-1}}{2.99792458 \times 10^{10}}. $$

As 1 GHz = 109 Hz, the numerical conversion can be expressed as
 * $$\tilde\nu / \text{cm}^{-1} \approx \frac{\nu / \text{GHz}}{30}.$$

Effect of vibration on rotation
The population of vibrationally excited states follows a Boltzmann distribution, so low-frequency vibrational states are appreciably populated even at room temperatures. As the moment of inertia is higher when a vibration is excited, the rotational constants (B) decrease. Consequently, the rotation frequencies in each vibration state are different from each other. This can give rise to "satellite" lines in the rotational spectrum. An example is provided by cyanodiacetylene, H−C≡C−C≡C−C≡N.

Further, there is a fictitious force, Coriolis coupling, between the vibrational motion of the nuclei in the rotating (non-inertial) frame. However, as long as the vibrational quantum number does not change (i.e., the molecule is in only one state of vibration), the effect of vibration on rotation is not important, because the time for vibration is much shorter than the time required for rotation. The Coriolis coupling is often negligible, too, if one is interested in low vibrational and rotational quantum numbers only.

Effect of rotation on vibrational spectra
Historically, the theory of rotational energy levels was developed to account for observations of vibration-rotation spectra of gases in infrared spectroscopy, which was used before microwave spectroscopy had become practical. To a first approximation, the rotation and vibration can be treated as separable, so the energy of rotation is added to the energy of vibration. For example, the rotational energy levels for linear molecules (in the rigid-rotor approximation) are

 * $$E_\text{rot} = hc BJ(J + 1).$$

In this approximation, the vibration-rotation wavenumbers of transitions are

 * $$\tilde\nu = \tilde\nu_\text{vib} + BJ(J'' + 1) - B'J'(J' + 1),$$

where $$B$$ and $$B'$$ are rotational constants for the upper and lower vibrational state respectively, while $$J$$ and $$J'$$ are the rotational quantum numbers of the upper and lower levels. In reality, this expression has to be modified for the effects of anharmonicity of the vibrations, for centrifugal distortion and for Coriolis coupling.

For the so-called R branch of the spectrum, $$J' = J'' + 1$$ so that there is simultaneous excitation of both vibration and rotation. For the P branch, $$J' = J'' - 1$$ so that a quantum of rotational energy is lost while a quantum of vibrational energy is gained. The purely vibrational transition, $$\Delta J=0$$, gives rise to the Q branch of the spectrum. Because of the thermal population of the rotational states the P branch is slightly less intense than the R branch.

Rotational constants obtained from infrared measurements are in good accord with those obtained by microwave spectroscopy, while the latter usually offers greater precision.

Spherical top
Spherical top molecules have no net dipole moment. A pure rotational spectrum cannot be observed by absorption or emission spectroscopy because there is no permanent dipole moment whose rotation can be accelerated by the electric field of an incident photon. Also the polarizability is isotropic, so that pure rotational transitions cannot be observed by Raman spectroscopy either. Nevertheless, rotational constants can be obtained by ro–vibrational spectroscopy. This occurs when a molecule is polar in the vibrationally excited state. For example, the molecule methane is a spherical top but the asymmetric C-H stretching band shows rotational fine structure in the infrared spectrum, illustrated in rovibrational coupling. This spectrum is also interesting because it shows clear evidence of Coriolis coupling in the asymmetric structure of the band.

Linear molecules

The rigid rotor is a good starting point from which to construct a model of a rotating molecule. It is assumed that component atoms are point masses connected by rigid bonds. A linear molecule lies on a single axis and each atom moves on the surface of a sphere around the centre of mass. The two degrees of rotational freedom correspond to the spherical coordinates θ and φ which describe the direction of the molecular axis, and the quantum state is determined by two quantum numbers J and M. J defines the magnitude of the rotational angular momentum, and M its component about an axis fixed in space, such as an external electric or magnetic field. In the absence of external fields, the energy depends only on J. Under the rigid rotor model, the rotational energy levels, F(J), of the molecule can be expressed as,

 * $$ F\left( J \right) = B J \left( J+1 \right) \qquad J = 0,1,2,...$$

where $$ B $$ is the rotational constant of the molecule and is related to the moment of inertia of the molecule. In a linear molecule the moment of inertia about an axis perpendicular to the molecular axis is unique, that is, $$ I_B = I_C, I_A=0 $$, so
 * $$ B = {h \over{8\pi^2cI_B}}= {h \over{8\pi^2cI_C}}$$

For a diatomic molecule
 * $$ I=\frac{m_1m_2}{m_1 +m_2}d^2 $$

where m1 and m2 are the masses of the atoms and d is the distance between them.

Selection rules dictate that during emission or absorption the rotational quantum number has to change by unity; i.e., $$ \Delta J = J^{\prime} - J^{\prime\prime} = \pm 1 $$. Thus, the locations of the lines in a rotational spectrum will be given by

 * $$ \tilde \nu_{J^{\prime}\leftrightarrow J^{\prime\prime}} = F\left( J^{\prime} \right) - F\left( J^{\prime\prime} \right) = 2 B \left( J^{\prime\prime} + 1 \right) \qquad J^{\prime\prime} = 0,1,2,...$$

where $$J^{\prime\prime}$$ denotes the lower level and $$J^{\prime}$$ denotes the upper level involved in the transition.

The diagram illustrates rotational transitions that obey the $$\Delta J$$=1 selection rule. The dashed lines show how these transitions map onto features that can be observed experimentally. Adjacent $$J^{\prime\prime}{\leftarrow}J^{\prime}$$ transitions are separated by 2B in the observed spectrum. Frequency or wavenumber units can also be used for the x axis of this plot.

Rotational line intensities
The probability of a transition taking place is the most important factor influencing the intensity of an observed rotational line. This probability is proportional to the population of the initial state involved in the transition. The population of a rotational state depends on two factors. The number of molecules in an excited state with quantum number J, relative to the number of molecules in the ground state, NJ/N0 is given by the Boltzmann distribution as
 * $$\frac{N_J}{N_0} = e^{-\frac{E_J}{kT}} = e^{-\frac {BhcJ(J+1)}{kT}}$$,

where k is the Boltzmann constant and T the absolute temperature. This factor decreases as J increases. The second factor is the degeneracy of the rotational state, which is equal to 2J + 1. This factor increases as J increases. Combining the two factors
 * $$\text{population} \propto (2J + 1)e^{-\frac{E_J}{kT}}$$

The maximum relative intensity occurs at
 * $$J = \sqrt{\frac{kT}{2hcB}} - \frac{1}{2}$$

The diagram at the right shows an intensity pattern roughly corresponding to the spectrum above it.

Centrifugal distortion
When a molecule rotates, the centrifugal force pulls the atoms apart. As a result, the moment of inertia of the molecule increases, thus decreasing the value of $$ B $$, when it is calculated using the expression for the rigid rotor. To account for this a centrifugal distortion correction term is added to the rotational energy levels of the diatomic molecule.

 * $$ F\left( J \right) = B J \left( J+1 \right) - D J^2 \left( J+1 \right)^2 \qquad J = 0,1,2,...$$

where $$ D$$ is the centrifugal distortion constant.

Therefore, the line positions for the rotational mode change to

 * $$ \tilde \nu_{J^{\prime}\leftrightarrow J^{\prime\prime}} = 2 B \left( J^{\prime\prime} + 1 \right) - 4 D \left( J^{\prime\prime} +1 \right)^3 \qquad J^{\prime\prime} = 0,1,2,...$$

In consequence, the spacing between lines is not constant, as in the rigid rotor approximation, but decreases with increasing rotational quantum number.

An assumption underlying these expressions is that the molecular vibration follows simple harmonic motion. In the harmonic approximation the centrifugal constant $$ D$$ can be derived as
 * $$ D = \frac{h^3}{32 \pi^4 I^2 r^2 k c}$$

where k is the vibrational force constant. The relationship between $$ B$$ and $$ D$$
 * $$ D=\frac{4 B^3}{\tilde \omega ^2}$$

where $$ \tilde \omega $$ is the harmonic vibration frequency, follows. If anharmonicity is to be taken into account, terms in higher powers of J should be added to the expressions for the energy levels and line positions. A striking example concerns the rotational spectrum of hydrogen fluoride which was fitted to terms up to [J(J+1)]5.

Oxygen
The electric dipole moment of the dioxygen molecule, is zero, but the molecule is paramagnetic with two unpaired electrons so that there are magnetic-dipole allowed transitions which can be observed by microwave spectroscopy. The unit electron spin has three spatial orientations with respect to the given molecular rotational angular momentum vector, K, so that each rotational level is split into three states, J = K + 1, K, and K - 1, each J state of this so-called p-type triplet arising from a different orientation of the spin with respect to the rotational motion of the molecule. The energy difference between successive J terms in any of these triplets is about 2 cm−1 (60 GHz), with the single exception of J = 1←0 difference which is about 4 cm−1. Selection rules for magnetic dipole transitions allow transitions between successive members of the triplet (ΔJ = ±1) so that for each value of the rotational angular momentum quantum number K there are two allowed transitions. The 16O nucleus has zero nuclear spin angular momentum, so that symmetry considerations demand that K have only odd values.

Symmetric top
For symmetric rotors a quantum number J is associated with the total angular momentum of the molecule. For a given value of J, there is a 2J+1- fold degeneracy with the quantum number, M taking the values +J ...0 ... -J. The third quantum number, K is associated with rotation about the principal rotation axis of the molecule. In the absence of an external electrical field, the rotational energy of a symmetric top is a function of only J and K and, in the rigid rotor approximation, the energy of each rotational state is given by

F\left( J,K \right) = B J \left( J+1 \right) + \left( A - B \right) K^2 \qquad J = 0, 1, 2, \ldots \quad \mbox{and}\quad K = +J, \ldots, 0, \ldots, -J $$

where $$ B = {h\over{8\pi^2cI_B}} $$ and $$ A = {h\over{8\pi^2cI_A}} $$ for a prolate symmetric top molecule or $$ A = {h\over{8\pi^2cI_C}} $$ for an oblate molecule.

This gives the transition wavenumbers as

 * $$ \tilde \nu_{J^{\prime}\leftrightarrow J^{\prime\prime},K} = F\left( J^{\prime},K \right) - F\left( J^{\prime\prime},K \right)

= 2 B \left( J^{\prime\prime} + 1 \right) \qquad J^{\prime\prime} = 0,1,2,...$$

which is the same as in the case of a linear molecule. With a first order correction for centrifugal distortion the transition wavenumbers become
 * $$ \tilde \nu_{J^{\prime}\leftrightarrow J^{\prime\prime},K} = F\left( J^{\prime},K \right) - F\left( J^{\prime\prime},K \right)

= 2 \left(B - 2D_{JK}K^2 \right) \left( J^{\prime\prime} + 1 \right) -4D_J\left(J^{\prime\prime}+1\right)^3 \qquad J^{\prime\prime} = 0,1,2,...$$

The term in DJK has the effect of removing degeneracy present in the rigid rotor approximation, with different K values.

Asymmetric top

The quantum number J refers to the total angular momentum, as before. Since there are three independent moments of inertia, there are two other independent quantum numbers to consider, but the term values for an asymmetric rotor cannot be derived in closed form. They are obtained by individual matrix diagonalization for each J value. Formulae are available for molecules whose shape approximates to that of a symmetric top.

The water molecule is an important example of an asymmetric top. It has an intense pure rotation spectrum in the far infrared region, below about 200 cm−1. For this reason far infrared spectrometers have to be freed of atmospheric water vapour either by purging with a dry gas or by evacuation. The spectrum has been analyzed in detail.

Quadrupole splitting
When a nucleus has a spin quantum number, I, greater than 1/2 it has a quadrupole moment. In that case, coupling of nuclear spin angular momentum with rotational angular momentum causes splitting of the rotational energy levels. If the quantum number J of a rotational level is greater than I, 2I + 1 levels are produced; but if J is less than I, 2J + 1 levels result. The effect is one type of hyperfine splitting. For example, with 14N in HCN, all levels with J > 0 are split into 3. The energies of the sub-levels are proportional to the nuclear quadrupole moment and a function of F and J. where, J + I − 1, …,. Thus, observation of nuclear quadrupole splitting permits the magnitude of the nuclear quadrupole moment to be determined. This is an alternative method to the use of nuclear quadrupole resonance spectroscopy. The selection rule for rotational transitions becomes
 * $$\Delta J = \pm 1, \Delta F = 0, \pm 1 $$

Stark and Zeeman effects
In the presence of a static external electric field the 2J + 1 degeneracy of each rotational state is partly removed, an instance of a Stark effect. For example, in linear molecules each energy level is split into J + 1 components. The extent of splitting depends on the square of the electric field strength and the square of the dipole moment of the molecule. In principle this provides a means to determine the value of the molecular dipole moment with high precision. Examples include carbonyl sulfide, OCS, with. However, because the splitting depends on μ2, the orientation of the dipole must be deduced from quantum mechanical considerations.

A similar removal of degeneracy will occur when a paramagnetic molecule is placed in a magnetic field, an instance of the Zeeman effect. Most species which can be observed in the gaseous state are diamagnetic. Exceptions are odd-electron molecules such as nitric oxide, NO, nitrogen dioxide,, some chlorine oxides and the hydroxyl radical. The Zeeman effect has been observed with dioxygen,

Rotational Raman spectroscopy
Molecular rotational transitions can also be observed by Raman spectroscopy. Rotational transitions are Raman-allowed for any molecule with an anisotropic polarizability which includes all molecules except for spherical tops. This means that rotational transitions of molecules with no permanent dipole moment, which cannot be observed in absorption or emission, can be observed, by scattering, in Raman spectroscopy. Very high resolution Raman spectra can be obtained by adapting a Fourier Transform Infrared Spectrometer. An example is the spectrum of. It shows the effect of nuclear spin, resulting in intensities variation of 3:1 in adjacent lines. A bond length of 109.9985 ± 0.0010 pm was deduced from the data.

Instruments and methods
The great majority of contemporary spectrometers use a mixture of commercially available and bespoke components which users integrate according to their particular needs. Instruments can be broadly categorised according to their general operating principles. Although rotational transitions can be found across a very broad region of the electromagnetic spectrum, fundamental physical constraints exist on the operational bandwidth of instrument components. It is often impractical and costly to switch to measurements within an entirely different frequency region. The instruments and operating principals described below are generally appropriate to microwave spectroscopy experiments conducted at frequencies between 6 and 24 GHz.

Absorption cells and Stark modulation
A microwave spectrometer can be most simply constructed using a source of microwave radiation, an absorption cell into which sample gas can be introduced and a detector such as a superheterodyne receiver. A spectrum can be obtained by sweeping the frequency of the source while detecting the intensity of transmitted radiation. A simple section of waveguide can serve as an absorption cell. An important variation of the technique in which an alternating current is applied across electrodes within the absorption cell results in a modulation of the frequencies of rotational transitions. This is referred to as Stark modulation and allows the use of phase-sensitive detection methods offering improved sensitivity. Absorption spectroscopy allows the study of samples that are thermodynamically stable at room temperature. The first study of the microwave spectrum of a molecule was performed by Cleeton & Williams in 1934. Subsequent experiments exploited powerful sources of microwaves such as the klystron, many of which were developed for radar during the Second World War. The number of experiments in microwave spectroscopy surged immediately after the war. By 1948, Walter Gordy was able to prepare a review of the results contained in approximately 100 research papers. Commercial versions of microwave absorption spectrometer were developed by Hewlett-Packard in the 1970s and were once widely used for fundamental research. Most research laboratories now exploit either Balle-Flygare or chirped-pulse Fourier transform microwave (FTMW) spectrometers.

Fourier transform microwave (FTMW) spectroscopy
The theoretical framework underpinning FTMW spectroscopy is analogous to that used to describe FT-NMR spectroscopy. The behaviour of the evolving system is described by optical Bloch equations. First, a short (typically 0-3 microsecond duration) microwave pulse is introduced on resonance with a rotational transition. Those molecules that absorb the energy from this pulse are induced to rotate coherently in phase with the incident radiation. De-activation of the polarisation pulse is followed by microwave emission that accompanies decoherence of the molecular ensemble. This free induction decay occurs on a timescale of 1-100 microseconds depending on instrument settings. Following pioneering work by Dicke and co-workers in the 1950s, the first FTMW spectrometer was constructed by Ekkers and Flygare in 1975.

Balle–Flygare FTMW spectrometer
Balle, Campbell, Keenan and Flygare demonstrated that the FTMW technique can be applied within a "free space cell" comprising an evacuated chamber containing a Fabry-Perot cavity. This technique allows a sample to be probed only milliseconds after it undergoes rapid cooling to only a few kelvins in the throat of an expanding gas jet. This was a revolutionary development because (i) cooling molecules to low temperatures concentrates the available population in the lowest rotational energy levels. Coupled with benefits conferred by the use of a Fabry-Perot cavity, this brought a great enhancement in the sensitivity and resolution of spectrometers along with a reduction in the complexity of observed spectra; (ii) it became possible to isolate and study molecules that are very weakly bound because there is insufficient energy available for them to undergo fragmentation or chemical reaction at such low temperatures. William Klemperer was a pioneer in using this instrument for the exploration of weakly bound interactions. While the Fabry-Perot cavity of a Balle-Flygare FTMW spectrometer can typically be tuned into resonance at any frequency between 6 and 18 GHz, the bandwidth of individual measurements is restricted to about 1 MHz. An animation illustrates the operation of this instrument which is currently the most widely used tool for microwave spectroscopy.

Chirped-Pulse FTMW spectrometer
Noting that digitisers and related electronics technology had significantly progressed since the inception of FTMW spectroscopy, B.H. Pate at the University of Virginia designed a spectrometer which retains many advantages of the Balle-Flygare FT-MW spectrometer while innovating in (i) the use of a high speed (>4 GS/s) arbitrary waveform generator to generate a "chirped" microwave polarisation pulse that sweeps up to 12 GHz in frequency in less than a microsecond and (ii) the use of a high speed (>40 GS/s) oscilloscope to digitise and Fourier transform the molecular free induction decay. The result is an instrument that allows the study of weakly bound molecules but which is able to exploit a measurement bandwidth (12 GHz) that is greatly enhanced compared with the Balle-Flygare FTMW spectrometer. Modified versions of the original CP-FTMW spectrometer have been constructed by a number of groups in the United States, Canada and Europe. The instrument offers a broadband capability that is highly complementary to the high sensitivity and resolution offered by the Balle-Flygare design.

title: Rotational spectroscopy


text:
1761 in music

Events

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 * Gottfried August Homilius – 32 Praeludia zu geistlichen Liedern vor zwey Claviere und Pedal
 * Wolfgang Amadeus Mozart –
 * Andante in C major for harpsichord, K. 1a
 * Allegro in C major for harpsichord, K. 1b
 * Allegro in F major for harpsichord, K. 1c
 * Minuet in F major for harpsichord, K. 1d
 * Simon Simon – Pièces de clavecin, Op. 1
 * Ludwig Zoschinger – Concors digitorum discordia seu 4 Partiæ
 * Johann Adolph Hasse
 * La Scusa
 * Il Nome

Methods and theory writings

 * Jean-Philippe Rameau – Origine des sciences

Births

 * January 20 – Giovanni Domenico Perotti, composer (died 1825)
 * January 22 – Georg Nikolaus von Nissen, biographer of Mozart (died 1826)
 * January 23 – Friedrich von Matthisson, librettist (died 1831)
 * January 26 – Jens Zetlitz, songwriter (died 1821)
 * February 15 – Jacob Kimball, Jr., composer (died 1826)
 * February 20 – Johann Christian Ludwig Abeille, pianist and composer
 * February 22 – Erik Tulindberg, composer (died 1814)
 * April 20 – Johann Gottlieb Karl Spazier, composer
 * May 3 – August von Kotzebue, librettist (died 1819)
 * June 13 – Antonín Vranický or Wranitzky, violinist and composer (died 1820)
 * June 15 – Charles Henry Wilton, British musician (died 1832)
 * July 20 – Joseph Lefebvre, composer
 * September 24 – F.L.Æ. Kunzen, composer
 * October 9 – Pierre Gaveaux, composer and operatic tenor (died 1825)
 * date unknown
 * Antoine Hugot, composer (died 1803)
 * John Andrew Stevenson, composer (died 1833)

Deaths

 * January 3 – Willem de Fesch, violinist and composer (born 1687)
 * January 18 – Francesco Feo, opera composer (born 1691)
 * February 15 – Carlo Cecere, composer (born 1706)
 * March 7 – Antonio Palella, composer
 * March 27 – Johann Ludwig Steiner, composer
 * April 10 – Cecilia Elisabeth Würzer, German-Swedish singer
 * June 12 – Meinrad Spiess, composer
 * July 9 – Carl Gotthelf Gerlach, organist (born 1704)
 * October 7 – Johann Pfeiffer, German composer (born 1697)
 * date unknown
 * Adam Falckenhagen, lutenist and composer (born 1697)
 * Newburgh Hamilton, librettist (born 1691)

title: 1761 in music


text:
A52 road

The A52 is a major road in the East Midlands, England. It runs east from a junction with the A53 at Newcastle-under-Lyme near Stoke-on-Trent via Ashbourne, Derby, Stapleford, Nottingham, West Bridgford, Bingham, Grantham, Boston and Skegness to the east Lincolnshire coast at Mablethorpe. It is approximately 147 mi long.

Route length
According to the AA, Newcastle-under-Lyme to Derby takes 56 minutes, Derby to Boston takes 1 hour and 40 minutes (100 minutes), and Boston to Mablethorpe takes 1 hour and 2 minutes (62 minutes), taking 3 hours and 38 minutes (218 minutes) to travel the whole distance.

Brian Clough Way
The mainly dual-carriageway 20.0 km stretch between The Pentagon Island in Derby and the Queen's Medical Centre in Nottingham was named Brian Clough Way in 2005 to honour the late Derby County and Nottingham Forest football manager Brian Clough.

Nantwich, Chesire
Historically the A52 used to start at Nantwich in Cheshire, but was renumbered to become the A500, the A531, and the B5500—the A500 sections later becoming unclassified.

Newcastle-under-Lyme – Derby
The road starts as Ryecroft from the roundabout with the A34 and B5367. It is dual carriageway until the next roundabout, forming part of the Newcastle ring road, with the A527 and A53. It passes the leisure centre on the right, then veers right at a junction with the B5045 (which continues on the main road), where it enters the City of Stoke-on-Trent. As Hartshill Road, it passes the Royal Stoke University Hospital and enters the town of Stoke-upon-Trent. It takes two possible routes around the town centre, meeting the A500 D Road. It goes under the West Coast Main Line near Stoke-on-Trent railway station and becomes Leek Road, passing one campus (Leek Road) of Staffordshire University. It meets the A50 at a roundabout at Joiner's Square near Hanley. It meets the A5008 and A5009 (for Leek) at crossroads, where it turns right. There is a junction with the A5272 (for Berry Hill). As Werrington Road in Bucknall it passes the former Mitchell High School and enters Staffordshire and the borough of the Staffordshire Moorlands. It passes through Ash Bank and Staffordshire, then meets the A520 (for Leek) at crossroads, then overlaps the A522 (for Cheadle). It passes through the villages of Kingsley and then Froghall where it crosses over the Churnet Valley Railway and Cauldon Canal, before meeting the A521 and B5053 (for Ipstones). It passes through Whiston and meets the B5417 (for Oakamoor). It meets the A523 (for Leek) and passes through Swinscoe, then briefly enters East Staffordshire.

The road enters Derbyshire and the Derbyshire Dales district where it crosses the River Dove over the Hanging Bridge near the junction with the B5032 at Mayfield close to the Queens Arms Hotel. The £3 million 1.5 mi Ashbourne Relief Road opened in October 1994. There is a roundabout for the exit to Ashbourne and one with the A515. The road climbs up the side of the Dove Valley, and there is a central overtaking/crawler lane. The roundabout with the eastern exit to Ashbourne is near an old airfield which is now an industrial estate. The area around the next section of road to Derby has links with Bonnie Prince Charlie. It passes through Brailsford and the Rose and Crown and at Kirk Langley, there is a junction with the B5020 for Mickleover.

It passes Mackworth, the Munday Arms and Mackworth Hotel, with part of the Mackworth Estate to the south and Markeaton Park. Entering Derby as Ashbourne Road, it meets the busy A38 at a roundabout, and Esso Mackworth Service Station. It passes the Shell Friargate garage on the left which has now been closed down. From here to the dual-carriageway is a popular pub crawl, with many student residences close by for the University of Derby, such as St Christopher's Court. Close by to the north is the new Markeaton campus of the university. The road splits into east and west sections, passing St John the Evangelist church on the left, with the easterly section being Agard Street and the westerly section being Friargate. From the traffic lights at the eastern end of both, the road becomes Ford Street, passing the Friargate Studios.

Derby – Nottingham
It overlaps the £3.5 million (£ as of ), A601 Derby Inner Ring Road, which is called St Alkmunds Way and was opened on 30 July 1972. It is used by 70,000 motorists daily as they pass under the 2007 footbridge towards Pentagon Island. From the Radio Derby building (to the west of the city centre) to Nottingham, it is dual-carriageway. It crosses the River Derwent, the A601 leaves to the south, and it passes under the Midland Main Line as Eastgate. There is the Pentagon Island Grade Separated Junction (GSJ) with the A61 near Chaddesden. The westbound-direction is not grade-separated and meets the roundabout, thus causing many severe queues at rush-hour. Near Spondon, there is a large GSJ with the A5111 Derby outer ring road. The £4.6 million (£ as of ), 0.5 mi Borrowash Bypass Extension opened on 29 May 1980 as well the £6 million (£ as of ), Nottingham Road Diversion, from the Pentagon Island to Raynesway. Both sections totalled 2.5 mi. 0.5 mi before Borrowash, it enters the Borough of Erewash.

Further east, it is the main east–west route from Derby to Nottingham, connecting the two cities via the busy junction 25 of the M1 at Sandiacre. The £250,000 3 mi Borrowash Bypass opened in 1957, although the bridge at Ockbrook opened in 1969, from a roundabout with the A6005 to Hopwell Firs. The former route is partly the A6005. The 5 mi £2 million (£ as of ), Sandiacre Stapleford Bypass opened in December 1964, being built two years before junction 25 of the M1 had been opened although all the bridges and roundabout were part of the bypass. It was the first major road project opened by the 1964 Labour government. The former route is the B5010. It crosses the Nottingham section of the Midland Main Line, and the River Erewash and Erewash Canal, entering Nottinghamshire and the Borough of Broxtowe.

Bardill's Island roundabout provides a junction with Toton Lane (B6003), which connects to both Stapleford and the Toton Lane Park & Ride site that is linked to central Nottingham by the Nottingham Express Transit (NET) tramway. The roundabout is also near the George Spencer Academy and the garden centre after which it is named. The A52 then passes through Bramcote at the roundabout with the A6007 next to Bramcote leisure centre and becomes a three-lane dual carriageway, however the left lane is a bus lane. There is a right-turn at traffic lights for Wollaton Road (B6006) for Beeston near the Nurseryman pub.

It enters the City of Nottingham at the A6464 Priory roundabout (Woodside Road leading to the A6005) in Lenton Abbey with the Shell Priory  garage on the right, and the Wollaton Miller and Carter Steakhouse on the left on Wollaton Vale road. To the left is Wollaton Park and nearby to the south is the University of Nottingham. The junction at the Queen's Medical Centre with the A6514 Middleton Boulevard was originally a roundabout, but became a GSJ, costing £3.7 million in late 1983. It then turns right and follows Clifton Boulevard (Ring Road) (after just under 2 miles crossing Clifton Bridge over the River Trent) as far as the A60 roundabout, where it continues East towards the A1. The former route through Nottingham is now the A6200, then down Angel Row, Wheeler Gate, Lister Gate then through what is now the Broadmarsh Centre and past the railway station on Carrington Street, through The Meadows as Arkwright Street to a point near the A60/A6011 junction, over Trent Bridge and along the current A6520 Radcliffe Road. South of here it follows the former A614 as Clifton Boulevard. There is a junction for Abbey Street (A6005 – former A453) which was originally a much smaller temporary flyover, but was improved in June 1990 at a cost of £5.5 million, which is where the former A614 terminated. It crosses the Beeston Canal and Nottingham – Derby/Loughborough railway line and follows the Clifton Boulevard around the south of Nottingham. It overlaps the A453, then the A453 exits for the M1 and Clifton near the Texaco Silverdale Service Station and The Becket School.

One of the bridges over the Trent at Clifton Bridge includes a section of the former B680 (which followed the route into Nottingham now used by the A453). The 275 ft east bridge opened in 1958, being officially opened by Princess Alexandra, The Honourable Lady Ogilvy. The bridge was widened, with the west bridge, to dual-carriageway as the A614 as part of a 1+1/4 mi £3.2 million section, opening in 1972. This was the completion of the dual-carriageway Nottingham ring-road. It enters the borough of Rushcliffe where it crosses the former Great Central Main Line and meets the A60 (for Ruddington and the Nottingham South Premier Inn), then the A606 at busy roundabouts. This section from the A606 roundabout, near the Wheatcroft Garden Centre, to the Dunkirk junction (current A6005, then the A453) – the Nottingham Ring Road – was opened in 1963 as mostly single carriageway. The section from Clifton Bridge to the A60 roundabout was dualled in December 1968. The £6 million 2 mi section from Gamston to Lings Bar opened in September 1981 as Gamston Lings Bar Road. It passes close to Tollerton Airfield and a large Morrisons (former Safeway), and crosses the Grantham Canal meeting the former route (A6011) at a busy roundabout near the Bridge pub. The section from the QMC to the A606 Wheatcroft Island roundabout used to be the A614 until the Gamston section was opened. The former route of the A52 into Nottingham is now the A6200 and A6011.

Nottingham – Grantham
Heading east as Radcliffe Road with Bassingfield to the right, the £25,000 (£ as of ), dual-carriageway section from Holme House built in 1956 finishes at the start of the Radcliffe on Trent bypass as Grantham Road. There is the BP Pierrepont Filling Station just before the turn-off for Radcliffe on Trent. This stretch has SPECS cameras along it. Close by is the Holme Pierrepont National Watersports Centre. The road goes past Upper Saxondale, then meets the A46 at the large Saxondale roundabout, which has the Shell Saxondale garage. The road runs roughly parallel with the Nottingham-Grantham railway between Radcliffe on Trent and Grantham. From the A46, the road heads east past Bingham on the £2.6 million (£ as of ), 2 mi Bingham bypass opened in December 1986. The road passes the Murco Kings Service Station on the left. There is a left turn for Scarrington, then it passes a HM Prison Whatton at Whatton-in-the Vale, near to where it crosses the River Smite.

It passes the Vale of Belvoir hotel, and after Elton where it passes the Manor Arms, it enters Leicestershire, the district of Melton, and the Vale of Belvoir at the start of the Bottesford bypass, which opened in February 1989 with an extremely wide concrete £3 million (£ as of ), 3 mi two-way road.

It passes by Muston and enters Lincolnshire and South Kesteven at the crossing of Sewstern Lane (Viking Way) next to the popular Muston Gap, passing through Sedgebrook. Belvoir Castle can be seen in the distance. The road climbs the steep Mill Hill near Barrowby, crosses the A1 and becomes Barrowby Road. The section of road from Radcliffe on Trent to Grantham was planned to become a dual-carriageway in the 1990s, but there are no plans at present.

It meets a roundabout with Barrowby Gate, next to the Muddle Go Nowhere, passing through Green Hill. At the bottom of Barrowby Road is a low-height railway bridge, which in 2005 was the most-hit railway bridge in the UK. Until only recently this busy trunk road was part of the High Street in Grantham; now it is diverted alongside the East Coast Main Line on Sankt Augustin Way, which is also the A607.

At the start of Sankt Augustin Way, the road passes an Asda on the left. It meets Dysart Road at traffic lights and turns left at a one way system onto Wharf Road, passing a large Morrisons store and Churchills pub, then turning right at traffic lights onto London Road, passing Sainsburys and the Reindeer Inn. The most sensible route around Grantham is to follow the A1 from Barrowby and take the A607 exit into Grantham, although there is a low bridge (13') on Springfield Road (another part of the A607), which was the UK's most-hit bridge in 2006.

There have been plans for an A52 bypass south of Grantham, which have many cycle-riding objectors. South of the town, it meets the B1174 at traffic lights near the Spotted Cow, with the Total St Leonards Service Station on the left and Pizza Hut and McDonald's on the right.

Grantham – Boston
This section of road is known locally as The Ramper, a name from the turnpike era.

From Grantham, which was the A52's original eastern end, the road continues as Bridge End Road passing the White Lion, then Somerby Hill eastwards, passing the Shell Somerby Hill Service Station on the left, rising up the valley of the River Witham to reach the ancient Ermine Street Roman road at the B6403/B1176 roundabout, which it follows for about 0.5 mi. Ermine Street continues as the B6403 northwards at Cold Harbour. Traffic for Skegness may want to take the A153 instead (via the Sleaford bypass), as from Boston – Wainfleet, the traffic slows down. It follows High Dike, and there is a left turn for Welby and a right turn for Ropsley.

There is a crossroads with the left for Oasby. There is a right turn for Braceby, then just before a right turn for Haceby, the road enters North Kesteven. There are turnings for Dembleby and Newton and passes through Scott Willoughby. It meets the A15 at the Threekingham Bar roundabout near Osbournby becoming Holland Road, and passes through Threekingham and crosses Mareham Lane (a Roman road), with the Holland Road Service Station on the right, where it re-enters South Kesteven. From here to the South-Forty Foot Drain (about 5 mi), the road lies on the border of the districts of North Kesteven and South Kesteven. There are crossroads with the B1394 (for Swaton and Horbling), and the road meets the B1177 from nearby Billingborough at Bridge End, becoming Bridge End Causeway.

At Donington High Bridge, it enters the district of South Holland next to the Sloop Inn. It passes over the Sleaford-Spalding railway and at Donington there is a roundabout with the A152 (the former name of the A52 east of Grantham). It follows a 1 mi bypass, which opened in the early 1990s, to the north becoming Bicker Road and there is a left turn for Northorpe. It enters the borough of Boston just before the 1+1/2 mi bypass to the south of Bicker, which opened in the early 1990s, where it meets the B1181 and becomes Donington Road. It passes the Texaco Bicker Bar Service Station on the left at the roundabout with the A17. It meets a roundabout for Swineshead and passes through Drayton, meets the B1391 as Abbey Lane, then Drayton Road. At Baythorpe passing the popular 2014 FARMA award-winning Manor Farm Shop Best UK small farm shop it becomes Boston Road and the B1192 joins to the left at Kirton Holme. At the Poachers Hotel it becomes Swineshead Road. There are crossroads again with the B1192 (for Hubbert's Bridge to the left) at the Four Crossroads Inn at Baker's Bridge. Near Boston, you will not find a straighter or flatter road, as the road follows the New Hammond Beck.

It passes Wyberton Fen and meets a roundabout with a Tesco superstore and B&Q on the left at Chain Bridge. The Hammer & Pincers pub is on the left just before a roundabout, where the main route follows to the left, and the straight-on direction is for Wyberton. The Alban Retail Park is on the right before it crosses the South Forty-Foot Drain and railway at a level crossing, then meets the A1121 from the left at a mini-roundabout close to a Peugeot, Citroën and BMW garage. It enters Boston as Sleaford Road along a long straight avenue of trees, passing the Shell Boston garage on the right.

There are crossroads for Brothertoft Road (A1137), which can be used to avoid the busy town centre, then a mini-roundabout with Carlton Road becoming Queen Street. There are crossroads, with Asda to the left, just before a level crossing with the railway near the railway station. There is a mini-roundabout with West Street to the left near The Eagle pub and it becomes Liquorpond Street. There is a retail park with a McDonald's on the right. There are some crossroads with King Street, then Marriotts Mazda garage on the left before a roundabout with the A16 Spalding Road (which it overlaps through Boston). Some residents want a bypass. An alternative for cars could be to take the B1192/B1184 through Hubbert's Bridge and Sibsey, rejoining at Old Leake.

Boston – Mablethorpe
In Boston, it follows the inner relief road, where it becomes John Adams Way, which crosses the River Witham (where it is tidal) on the £220,000 Haven Bridge, which opened in June 1966. It passes the Esso John Adams Way Service Station on the right, close to two speed cameras in either direction and overshadowed by the floodlights of Boston United. There are traffic lights at a roundabout with the A1137/B1183 (for Horncastle), where the inner-relief road ends near the Red Cow Hotel. Boston Shopping Park is on the left, and the road becomes Spilsby Road where it crosses the Maud Foster Drain] at Bargate Bridge near Maud Foster Windmill. It passes Holy Trinity church on the left, and the Mill Inn which is close to Boston High School. The road has a roundabout with the A16 and becomes Wainfleet Road. At the Burton Corner roundabout, Skegness is signposted in the direction of the A16. It passes the Burton House on the right, then passes the Ball House Inn at Willoughby Hills. It crosses the Hobhole Drain at Haltoft End where it passes the Freiston Centre for Environmental Education and the Castle Inn. There are right turns for Butterwick and it goes through Benington becoming Main Road where it passes All Saints church and the Admiral Nelson, then Leverton where it passes St Helena's church. Near to Leverton Highgate is the Traveller's Rest cafe, and Three Horseshoes. It passes through Old Leake, and meets the B1184 near The Giles School and passes the Bricklayer's Arms and passes near to the Angel Inn in Wrangle, then the primary school towards Wrangle Lowgate.

The section between Boston and Skegness has had straighter sections since the late 1990s. Just before a bend to the right where it becomes Holland Lane then Main Road, it enters the district of East Lindsey. There are left turns for Friskney. It then passes through Friskney Tofts, where it passes the Barley Mow near Friskey Eaudyke then Wainfleet Tofts. It passes near to Wainfleet St Mary (near the home of Batemans Brewery) which is now bypassed, and meets the B1195, then crosses the Steeping River and over a level crossing. There is a left turn for Croft and it passes the Pine Trees Leisure Park. Entering Skegness as Wainfleet Road, it passes Skegness Retail Park with a Pizza Hut and Skegness Hospital. It meets the B1451 roundabout in the centre of Skegness near a Morrisons (former Safeway) superstore and the railway station becoming Roman Bank. After the junction with the A158 (from Lincoln), it is no longer a trunk road, and passes the Total North End Service Station on the right.

North of Skegness, it meets Seathorne near the primary school, Garden City pub, Skegness Water Leisure Park, Butlins and Fantasy Island. It passes through Ingoldmells and the primary school as Skegness Road, heading slightly westwards through Hogsthorpe as South End then High Street. At Mumby, it meets the B1449 as Station Road and passes the St Thomas of Canterbury church and Red Lion, with a left turn for Cumberworth. Passing through Huttoft there is the primary school and the Axe and Cleaver Inn on Mumby Road and Sutton Road. Next is Sandilands and it reaches Sutton-on-Sea as Huttoft Road, passing the primary school and meets the A1111 at a roundabout, becoming Trusthorpe Road. At Trusthorpe as Sutton Road, it passes some radio masts. It reaches Mablethorpe as Seaholme Road and ends at the junction of Victoria Road and the High Street (A1104).

title: A52 road


text:
A52

A52 may refer to:
 * Ubiquitin A-52 residue ribosomal protein fusion product 1, a human gene

Roads

 * A52 road (England), a road connecting Newcastle-under-Lyme and Mablethorpe
 * A52 motorway (France), a road connecting Aubagne and the A50
 * Bundesautobahn 52, a highway in Germany usually referred to as A52
 * A52 motorway (Italy), a ring road around Milan
 * A52 motorway (Switzerland), a road connecting Zumikon and Hinwil
 * Autovía A-52 Spain, highway connecting Benavente and O Porriño

Other

 * Samsung Galaxy A52, an Android smartphone
 * The A/52 audio codec, also known as AC-3 or Dolby Digital
 * One of the Encyclopaedia of Chess Openings codes for the Budapest Gambit in chess
 * Action 52, a video game developed by Active Enterprises

title: A52