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M4

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M4
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From:Chiswick, Middlesex (TQ195782)
To:Pont Abraham, Carmarthenshire (SN575071)
Via:Slough, Reading, Swindon, Bath, Bristol, Newport, Cardiff, Port Talbot, Swansea
Length:191.9 miles (308.8 km)
Meets: M5, M25, M32, M48, M49, A33, A34, A4, A46, A48(M), A48, A308(M), A312, A329(M), A346, A350, A404(M), A419, A429, A449, A465, A470, A483, A4042, A4138, A4232
Former Number(s):A4, A4(M), A48(M) (Port Talbot and Morriston bypasses)
Old route now:M48, A404(M), A48(M) (Cardiff spur)
Primary Destinations
Heathrow Airport
Highway Authorities

Highways England • South Wales Trunk Road Agent

Traditional Counties

Berkshire • Buckinghamshire • Carmarthenshire • Glamorgan • Gloucestershire • Middlesex • Monmouthshire • Wiltshire

Route outline (key)
M4 Chiswick — Pont Abraham
M4 Maidenhead bypass
M4 Severn Bridge and approaches
Junction List
Unless otherwise indicated, access is both to and from the routes listed.
Former junctions are shown on a grey background.
Junc Westbound Eastbound
1 from A4 to A4
2 A4 A4
Services symbol.gif Heston services
3 A312 A312
4 (A408) (A408)
4b M25 M25
5 A4 A4
Services symbol.gif Datchet services
6 A335 A335
7 A4 A4
8 A308 A308
8/9 A308(M), A404(M) A308(M), A404(M)
Services symbol.gif Maidenhead services
9a Cox Green, White Waltham Cox Green, White Waltham
9b Temporary start of road A4
Services symbol.gif Warren Copse services
10 A329(M) A329(M)
11 A33 A33
Services symbol.gif Reading services
12 A4 A4
Services symbol.gif Ashes Copse services
13 A34 A34
14 A338 A338
Services symbol.gif Membury services
15 A346, A419 A346, A419
16 A3102 A3102
Services symbol.gif Ballard's Ash services
17 A350, A429 A350, A429
Services symbol.gif Leigh Delamere services
18 A46 A46
Services symbol.gif Pucklechurch services
19 M32 M32
20 M5 M5
21 to M48 from M48
21 A403 A403
Services symbol.gif Aust services
22 M49 M49
22 A466 A466
Toll (westbound only) Severn Bridge
23 from M48 to M48
23a B4245 B4245
Services symbol.gif Wilcrick services
24 A48, A449 A48, A449
25 to B4596 from B4596
25a to A4042 from A4042
26 A4051 A4051
27 B4591 B4591
28 A48, A467 A48, A467
29 to A48(M) from A48(M)
30 A4232 A4232
32 A470 A470
33 A4232 A4232
34 A4119 A4119
35 A473 A473
36 A4061, A4063 A4061, A4063
37 A4229 A4229
38 to A48 A48
Services symbol.gif Port Talbot services
39 from A48 --
40 A4107 A4107
41 A48 A48
42 A483 A483; to A48
43 A465 A465
44 A48 A48
45 A4067 A4067
46 A48 A48
47 A48 A48
48 A4138 A4138
49 to A48, A483 from A48, A483

The M4 is the London to South Wales Motorway. Running for about 190 miles from Chiswick in the west of the capital to a point some 12 miles southeast of Carmarthen in west Wales, it passes such important centres of population and industry as Reading, Swindon, Bristol, Cardiff, and Swansea. The route forms the bulk of the E30's Fishguard - Felixstowe route in the UK.

Globe.png
For detailed information about this topic, see CBRD Motorway Database: M4

Contents

Route

London - Reading

The road into London is one of few examples of truly urban major motorways which were built as intended. It was also a pioneer of modern features, boasting three CCTV cameras, detectors to report congestion and a never-used underfloor heating system which claimed there would never be a frost on the road. The elevated section claims to have been built without "any disruption" to the Great West Road beneath it.

The tensioned wire central reservation barrier fitted to the road at Langley was the first in the UK, and was used by TRL to test its effectiveness before the road opened.

Reading - Bath

Heading west towards Swindon

After Reading, the M4 becomes more rural and picturesque - travelling first through the North Wessex Downs, and then the southern Cotswolds. The motorway runs a few miles north of the A4 and the towns along it that, save for Swindon, are the main places that it serves. At junction 13 the motorway meets the major A34 north-south route, serving Newbury. At junction 14, Hungerford is served via the A338. Swindon has two junctions: junction 15, which serves also serves Marlborough via an extended A346, as well as the A417/A419 trunk dual carriageway to the M5 at Gloucester and junction 16, which serves western suburbs. Junction 17 serves Chippenham, with the A429 south of the junction having been renumbered A350 upon the opening of the motorway. Junction 18 with the A46 serves Bath.

Bath - Cardiff

Approaching the Second Severn Crossing from Newport

Cardiff - Pont Abraham

Elevated over Port Talbot

History

Perhaps surprisingly, the M4 may be counted Great Britain's second oldest motorway, as the Chiswick Flyover (then numbered A4, but now the first section of the M4) opened in 1959, a couple of months before the M1, M10, and M45. Other parts of this motorway started life as the A4(M) and A48(M), whilst the Severn and Wye Bridges – originally on the M4 but bypassed since 1996 by the Second Severn Crossing – now lie on the M48.

Opening dates

Globe.png
For detailed information about this topic, see CBRD Motorway Database: M4 Timeline

Future

Junctions

Brentford Interchange

M4J2 5 - Coppermine - 1295.jpg

Main Article: Brentwood Interchange
The Brentwood Interchange (junction 2) is a compact 'ironing-board' interchange.

Colnbrook Interchange

Colnbrook Interchange.png

Main Article: Colnbrook Interchange
The Colnbrook Interchange (junction 4b of the M4; junction 15 of the M25) is a large four-level stack interchange between the M4 and M25 motorways. It is unusual in that, in addition to the various different roads that make up the junction, there is also a railway line running through it.


Chieveley Interchange

M4J13.png

Main Article: Chieveley Interchange
The Chieveley Interchange (junction 13) was upgraded in the late 2000s to a 3-level roundabout.

Almondsbury Interchange

Almondsbury Interchange.png

Main Article: Almondsbury Interchange
The Almondsbury Interchange (junction 20 of the M4; junction 15 of the M5) is an important junction allowing direct interchange between the M4 and M5, and is additionally linked to junction 16 of the M5, which provides access to and from the A38. This junction was the first example of a four-level stack in the country. The link roads leading from the M4 to the M5 pass over the top level of the interchange whilst those from the M5 to the M4 pass underneath all other levels.


Coryton Interchange

M4 Motorway Intersection near Tongwynlais - Geograph - 609448.jpg

Main Article: Coryton Interchange
The Coryton Interchange (junction 32) is a very large 3-level roundabout, with the A470. The circulatory carriageway of the motorway is one of the longest in the country, clocking in at over a mile. The A470 mainline goes over the roundabout's north side, but under its south side.


Pont Abraham Interchange

M4; The Very End - West - Coppermine - 23287.jpg

Main Article: Pont Abraham Interchange
Pont Abraham is the westernmost motorway junction in Britain. Consisting of a roundabout with the A48 and A483, junction 49 is only one of two (junction 48 being the other one) motorway junctions signed with Welsh destinations first.

All Junctions


Structures

Second Severn Crossing

Second Severn Crossing.jpg

Main Article: Second Severn Crossing
The Second Severn Crossing was constructed between 1992 and 1996 to provide relief for the Severn Bridge and Wye Bridge between England and Wales. Upon completion, the M4 moved across from the original bridges (which became part of the M48) to the new bridge.

Brynglas Tunnels

Bryn Glas Tunnels M4 (Western Portal) - Geograph - 109133.jpg

Main Article: Brynglas Tunnels
The Brynglas Tunnels are situated on the Newport bypass, between junctions 25a and 26. They are twin-bored tunnels, each carrying two traffic lanes and opened in 1967. Until recently, the eastbound tunnel was lit by orange lighting, the westbound by white. Both tunnels have overhead lane control signals for contraflow purposes.

Services

Heston services

Hello Moto - Geograph - 899212.jpg

Main Article: Heston services
Heston services are one of only two MSAs within the M25. They are located on a cramped site within Greater London, between junctions 2 and 3.

Chieveley Services

Chieveley Services - Geograph - 1652843.jpg

Main Article: Chieveley services

These are situated where the M4 crosses the A34 near the village of Chieveley in Berkshire.

Leigh Delamere services

Leigh Delamere services, M4 eastbound - Geograph - 1015856.jpg

Main Article: Leigh Delamere services

Leigh Delamere services are located in Wiltshire between junctions 17 and 18. Originally, only the eastbound side was developed; the westbound side followed around ten years later.

Pont Abraham services

Pont Abraham Services - Geograph - 573375.jpg

Main Article: Pont Abraham services

Pont Abraham services are a single-site MSA located on the western terminal roundabout of the M4, at junction 49. It is operated by RoadChef.

Traffic Data

From http://www.dft.gov.uk/traffic-counts/

Link 2002 AADF 2006 AADF 2010 AADF 2014 AADF
J1-2 85937 90124 78182 93447
J2-3 95837 97379 85188 99632
J3-4 132852 133351 123890 129381
J4-4A 65318 71461 60418 59922
J4-A408 50783 43052 53909 52258
J4-4B 146092 143536 148143 159549
J4B-5 140319 144512 141194 146271
J5-6 135771 145431 128060 137696
J6-7 136395 125128 128356 124932
J7-A4 27369 28278 31309 32229
J7-8/9 139769 126506 133892 136613
J8/9-10 130353 129232 123557 126109
J10-11 123834 125859 117017 117587
J11-12 108780 122224 109193 105723
J12-13 90232 92102 86349 88807
J13-14 80802 83366 92727 83402
J14-15 80802 83366 92727 83402
J15-16 80474 86672 77290 77798
J16-17 67038 69764 69852 66812
J17-18 73967 78155 79457 70193
J18-19 79278 87907 85451 89253
J19-20 102913 107711 114949 119111
J20-21 53876 62682 60512 60787
J21-22 36805 43144 41665 42024
J22-23 55607 59472 62036 61144
J23-23A 67419 75935 71476 78770
J23A-24 72296 78821 83098 86222
J24-25 97161 104720 89804 101206
J25-25a 92393 96184 89062 110033
J25A-26 74213 77193 60186 80457
J26-27 101317 107891 107168 109620
J27-28 103039 111210 107226 113134
J28-29 98404 105764 97581 114617
J29-30 59821 64779 58683 70812
J30-32 75478 65230 61809 79623
J32-33 83553 94444 93820 99756
J33-34 78262 101443 99868 94257
J34-35 72719 77065 75313 82094
J35-36 60538 67396 65720 69251
J36-37 57605 64939 62182 69388
J37-38 52209 60872 62508 67295
J38-39 50994 63279 68452 69558*
J39-40 57856 67340 63881 72596*
J40-41 59008 64789 79473 56508
J41-42 60959 69214 75384 68382
J42-43 65682 71715 58313 79674
J43-44 69098 72067 80322 81629
J44-45 56084 65969 63298 68391
J45-46 57244 68748 69351 68359
J46-47 54720 64793 62318 64528
J47-48 43273 56293 48970 51721
J48-49 35264 38455 38945 44275

Miscellanea

  • The section of the M4 between junctions 19 and 23 has the the highest number of consecutive motorway-to-motorway junctions in the United Kingdom.
  • In 1999 a controversial bus lane was established on a 5.6-km stretch of the eastbound carriageway of the M4 between junction 3 and the start of the elevated section of the motorway near Brentford. Suspended in December 2010, it will be re-instated temporarily for the duration of the 2012 London Olympics.
Globe.png
For detailed information about this topic, see CBRD Motorway Database: M4 Bus Lane

External links

legislation.gov.uk

Welsh Government

CBRD



M4
JunctionsAlmondsbury Interchange • Aust Interchange • Awkley Interchange • Bray Interchange • Brentford Interchange • Caerleon Interchange • Cardiff West Interchange • Castleton Interchange • Cherry Lane Roundabout • Chieveley Interchange • Chiswick Roundabout • Coldra Interchange • Colnbrook Interchange • Concord Roundabout • Coryton Interchange • Cox Green Interchange • Cranford Parkway Interchange • Dock Way Junction • Earlswood Interchange • Glan Llyn Junction • Groes Interchange • Grove Park Interchange • Hambrook Interchange • Heathrow Interchange • Hendy Interchange • High Cross Interchange • Holyport Interchange • Huntercombe Spur • Langley Roundabout • Llandarcy Interchange • Llangyfelach Interchange • Lon-Las Interchange • M4 J31 • Magor Interchange • Malpas Interchange • Margam Interchange • Miskin Interchange • Newhouse • Pencoed Interchange • Penllergaer Interchange • Pentwyn Interchange • Pentyla Interchange • Pilning Interchange • Plough Hill Roundabout • Pont Abraham Interchange • Pyle Interchange • Rogiet Interchange • Sarn Interchange • Spittleborough Roundabout • Stanton St Quinton Roundabout • Taibach Interchange • The Thicket Roundabout • Theale Interchange • Three Mile Cross Interchange • Tormarton Interchange • Tredegar Park Interchange • Tuns Lane Interchange • Wickham Interchange • Winnersh Interchange • Ynysforgan Interchange
ServicesCardiff Gate services • Cardiff West services • Chieveley services • Heston services • Leigh Delamere services • Maidenhead services • Membury services • Pont Abraham services • Port Talbot services • Pucklechurch services • Reading services • Sarn Park services • Swansea West services • Warren Copse services • Wilcrick services
CrossingsBrynglas Tunnels • Chiswick Flyover • M4 Calcot Viaduct • M4 Carters Hill Bridge • New Thames Bridge • Second Severn Crossing • Severn Bridge • Wye Bridge
ProjectsM4/Newport Southern Bypass
RoadsE105 (London - Fishguard) • E30 • Longest Lane • M4/Airport Spur • M4/Newport Southern Bypass
Related Pictures
View gallery (488)
Hello Moto - Geograph - 899212.jpgIt Won't Be Called That When You Get There... - Coppermine - 21847.jpgSlip road up to elevated M4 - Geograph - 741937.jpgToll sign - Coppermine - 16164.jpgWestbound carriageway of M4 just east of J15 - Geograph - 276174.jpg
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LondonA1 • A1(M) • A10 • A101 • A11 • A11(M) • A127 • A13 • A2 • A2(M) (Kidbrooke - Falconwood) • A20 • A21 • A216 • A23 • A23(M) • A233 • A24 • A3 • A30 • A30/Sandbox • A4 • A4/Great West Road • A4/Slough - London • A40 • A40/Central London - Denham • A41 • A41/Central London - Watford • A41/Watford - Aylesbury • A5 • A5/Central London - Brockley • B269 • B519 • E1 (Old System) • E105 (London - Fishguard) • E107 (London - Tilbury) • E108 (London - Southend) • E13 • E15 • E2 (Old System) • E30 • E31 (via Carlisle) • E31 (via Newcastle) • E33 (London - Glasgow) • E5 (Old System) • E8 (Old System) • East Cross Route • Ermine Street • EuroVelo 2 • EuroVelo 5 • Great North Road • Holyhead Road • London Inner Ring Road • Longest Lane • M1 • M100 • M11 • M12 (Brentwood - Chelmsford) • M12 (Woodford - Brentwood) • M12 (Woodford - Maplin) • M13 • M14 • M15 • M16 • M20 • M23 • M25 • M3 • M30 • M40 • M41 • NCN1 • NCN13 • NCN20 • NCN21 • NCN4 • Northern and Western Motorway • Orbital Tunnel Route • RM3 • Ringway 2 • South Cross Route • T1 (Britain) • T10 (Britain) • T11 (Britain) • T12 (Britain) • T2 (Britain) • T3 (Britain) • T31 (Britain) • T32 (Britain) • T33 (Britain) • T34 (Britain) • T35 (Britain) • T4 (Britain) • T5 (Britain) • T6 (Britain) • T8 (Britain) • T9 (Britain) • Watling Street
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CardiffA4050 • A4053 (Cardiff) • A4054 • A4055 • A4056 • A4119 • A4160 • A4161 • A4232 • A4234 • A469 • A470 • A48 • A48(M) • A48(M) (Llantrisant Radial) • B4239 • B4258 (Llandaff) • B4258 (Roath - Gabalfa) • B4259 • B4260 (Penarth) • B4261 • B4261 (Llandaff - Llantrisant) • B4262 • B4267 • B4288 (Monmouthshire) • B4487 • B4488 • B4562 • E105 (London - Fishguard) • E30 • Hook Road • NCN8 • T10 (Britain) • T75 (Britain) • Western Tangential
SwanseaA4067 • A4068 (Morriston - Ystalyfera) • A4069 (Swansea) • A4070 • A4118 • A4216 • A4217 • A4230 • A465 • A475 (Swansea - Carmarthen) • A48(M) (Morriston Bypass) • A483 • A484 • B4247 • B4271 • B4290 • B4291 • B4292 • B4293 (Swansea) • B4294 (Gower) • B4295 • B4296 • B4433 • B4436 • B4489 • B4593 • B4603 • B4620 • B4625 • B5444 (Swansea) • E105 (London - Fishguard) • E30 • EuroVelo 1 • NCN4 • T10 (Britain) • T18 (Britain)
Motorways in Great Britain
Current MotorwaysM1 • M2 • M3 • M4 • M5 • M6 • M6 Toll • M8 • M9 • M11 • M18 • M20 • M23 • M25 • M26 • M27 • M32 • M40 • M42 • M45 • M48 • M49 • M50 • M53 • M54 • M55 • M56 • M57 • M58 • M60 • M61 • M62 • M65 • M66 • M67 • M69 • M73 • M74 • M77 • M80 • M90 • M180 • M181 • M271 • M275 • M602 • M606 • M621 • M876 • M898
A1(M) • A3(M) • A8(M) • A14(M) • A38(M) • A48(M) • A57(M) • A58(M) • A64(M) • A66(M) • A74(M) • A92(M) • A167(M) • A168(M) • A194(M) • A195(M) • A308(M) • A329(M) • A404(M) • A601(M) • A627(M) • A635(M) • A666(M) • A823(M) • A1058(M)
Motorway Spurs • (M4 Heathrow Spur • M25 T5 Spur • Walton Summit M'way)
Former MotorwaysM10 • M15 • M16 • M30 • M41 • M52 • M62 • M63 • M64 • M65 • M68 • M85 • M110 • M111 • M270 • M274 • M531 • M600
A2(M) • A4(M) • A5(M) • A8(M) • A11(M) • A18(M) • A20(M) • A21(M) • A23(M) • A36(M) • A40(M) (Central London) • A40(M) (Buckinghamshire) • A41(M) • A46(M) • A48(M) (Morriston) • A48(M) (Port Talbot) • A65(M) • A102(M) (North) • A102(M) (South) • A423(M) • A446(M) • A604(M) • A638(M) • A696(M) • A1231(M) • A6127(M) • A6138(M) • A6144(M)
Unbuilt MotorwaysM4 Toll • M12 (Woodford - Brentford) • M12 (Woodford - Maplin) • M12 (Brentwood - -Chelmsford) • M13 • M17 • M19 • M31 • M58 • M59 • M60 • M62 RR • M64 • M81 • M82 • M83 • M100 • M272 • M601 • M650
A2(M) • A6(M) (West) • A6(M) (East) • A48(M) • A59(M) • A61(M) • A556(M) • A695(M)
A Ring • Bilston Link • Belmont Link • B-W M'way • CME Bypass • CMW • Central Spine • Chippenham Spur • Coventry N-S M'way • Cublington Airport M'way • Denham Spur • Derby Urban M'way • Droitwich-Leicester M'way • East Coast M'way • EXR • East Kilbride M'way • E-W Underground M'way • Eastern M'way • Euroroute • Friars Goose Xing • Furness Link • Glasgow IRR • GM Western Relief Road • Hamilton-Cumbernauld M'way • Hook Road • Johnstone M'way • Kendal Link • Liverpool Inner M'way • LOX M'way • Malvern Radial • Manchester IRR • Morecambe Link • NE Urban M'way • NXR • N&W M'way • Paisley-Hamilton M'way • POLO • Princess P'way M'way • Reading Urban M'way • Ringway 2 • Sheffield Spur • S Bristol Spur • SCRPDR • SXR • Stirling Corner Link • Strensham-Solihill M'way • Strensham-Solihill M'way • TGAAR • Townhill Link • Trafford Park M'way • Warndon Radial • Watford Urban M'Way • Western Orbital • Weston Spur