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Motorway Widening

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Motorways are known to attract high volumes of traffic and often prove to be inadequate for the volumes of traffic now using them. One solution to the problem is to simply widen the motorway. However, this is not straight forward in terms of cost or engineering techniques required, and often causes local opposition relating to further traffic growth and environmental damage.

Widening Methods

'Future-proofed' Motorway

'Future-proofed' section of the M65

Due to the high cost of constructing a motorway and purchasing land, it is very rare that structures and alignments are built to enable easy widening later on. The M6 Preston and Lancaster Bypasses were designed with wide central reservations that easily allowed a third lane to be built, although in the case of Preston even more widening was later required using more advanced techniques. However, these motorways had intermittent hard shoulders to begin with. Other motorways designed with 'future-proofing' for eventual widening are the M65 between J1A-6, and the A329(M). This method is used more in continental Europe where land is not at such a high premium.

Symmetrical and Asymmetrical Widening

Symmetrical Widening on the M1

These methods involve widening the existing carriageways in situ, and therefore are often the most disruptive forms but are unavoidable in constrained areas. Typically, when using this method most bridges will not be widened with the immediate disadvantage of the finished works leaving intermittent hard shoulders, although at overbridges this may be mitigated by the creation of a bypass lane behind existing bridge piers, as on the M25 between J8-16. An early example of this type of widening was undertaken on the M4 Maidenhead Bypass, which still retains this formation today.

Parallel Widening - 'online'

Online Parallel Widening the M5

This method is often the least disruptive to the motorway mainline but it requires a suitable tract of land alongside the motorway in order to be carried out. Generally, a new carriageway is constructed alongside the existing motorway requiring the replacement of all structures - often with uneven sized spans - and extensive refurbishment of the original motorway formation to create a new wider motorway. It is commonly associated with the work to widen M5 Junctions 3-8 as it has several lengths where this was used. The uneven size spans at overbridges are evident particularly south of J4.

Parallel Widening - 'offline'

An alternative type of parallel widening is to just construct an entirely new motorway alongside and abandon the existing formation, returning it to nature. The best UK example of this is the A2 between Cobham and Pepperhill where the existing D3M formation was abandoned in favour a wholly new D4M alignment some 100-200 metres to the south, and a short length of the M6 near Longridge from the 1993-95 widening. Internationally, the biggest example of this is on the Italian A3 south of Naples where the abandoned motorway is still visible from the air.

Narrow Lanes

Narrow Lanes on the M60

This method is rare due to the safety implications it presents. Removing width from existing carriageway lanes to create an additional lane often negatively affects carriageway capacity and encourages 'bunching' of vehicles. However, as this method requires zero landtake it is the only option where the motorway is already constructed against the highway boundary. The only substantial examples of this method are on the M60 around Manchester, most notoriously between J12-15 eastbound.

Smart Motorway

All of the above methods are currently out of favour, instead Highways England and the Government currently prefer the implementation of Smart Motorways, which are detailed in a separate article.

Completed and Current Widening Projects

This page may need updating or rewriting for the reason stated below. If you have the knowledge, please consider updating!
This list is not currently exhaustive and needs input from others who may know!
Motorway Extents Standard (e.g. D2M to D3M) Completed
Chopsticks icon.png M1 5 - 8 D2M to D3M/D4M (including provision for M25) November 1983
Chopsticks icon.png M1 23A - 24 D3M to D4M 1991
Chopsticks icon.png M1 9 - 10
(northbound only)
D3M to D4M 1994
Chopsticks icon.png M1 21 - 21A D3M to D4M 1995 (?)
Chopsticks icon.png M1 42 - 43 D3M to D5M (including provision for M1-A1 link) 1999
Chopsticks icon.png M1 31 - 32 D3M to D4M 2008
Chopsticks icon.png M1 6A - 10 D3M to D4M with Collector/Distributor Lanes (J7-8) 2008
Chopsticks icon.png M1 25 - 28 D3M to D4M 2010
Chopsticks icon.png M2 1 - 4 D2M to D3M/D4M 2002
Chopsticks icon.png M3 11 - 14 D2 to D3M 1987 ?
Chopsticks icon.png M4 5 - 8/9 D2M to D3M 1971
Chopsticks icon.png M4 24 - 25 D2M to D3M 1982
Chopsticks icon.png M4 26 - 29 D2M to D3M 1982
Chopsticks icon.png M4 4 - 5 D3M to D4M 1989 ?
Chopsticks icon.png M4 18
(eastbound only)
D3M to D4M 2005
Chopsticks icon.png M4 29 - 32 D2M to D3M 2010
Chopsticks icon.png M5 3 - 4
(section north of Dayhouse Bank)
D2M to D3M 1979
Chopsticks icon.png M5 3 - 4
(section south of Dayhouse Bank)
D2M to D3M November 1984
Chopsticks icon.png M5 4A - 5 D2M to D3M 1986
Chopsticks icon.png M5 4 - 4A D2M to D3M 1988
Chopsticks icon.png M5 5 - 6 D2M to D3M 1988
Chopsticks icon.png M5 6 - 8 D2M to D3M 1993
Chopsticks icon.png M5 18 - 19 D3M to D4M 2004
Chopsticks icon.png M5 19 - 20 D3M to D4M
(staggered climbing lanes)
Chopsticks icon.png M5 17 - 18A
(northbound only)
D3M to D4M 2008
Chopsticks icon.png M6 29 - 32 D2M to D3M 1967
Chopsticks icon.png M6 33 - 35 D2M to D3M 1967
Chopsticks icon.png M6 30 - 32 D3M to D4M October 1995
Chopsticks icon.png M6 20 - 21A D3M to D4M 1996
Chopsticks icon.png M6 32
(southbound only)
D2M to D3M 2008
Chopsticks icon.png M6 32
(northbound only)
D2M to D3M 2015
Chopsticks icon.png M9 1 - 1A D3M to D4M 2013
Chopsticks icon.png M20 5 - 8 D2M to D3M with D2M Collector/Distributor Lanes (J5-6) 1993
Chopsticks icon.png M25 11 - 13 D3M to D4M 1991
Chopsticks icon.png M25 6 - 10 D3M to D4M 1995
Chopsticks icon.png M25 12 - 15 D4M to D5M/D6M 2005
Chopsticks icon.png M25 27 - 30 D3M to D4M 2010
Chopsticks icon.png M25 16 - 23 D3M to D4M 2011
Chopsticks icon.png M27 3 - 4 D3M to D4M 2009
Chopsticks icon.png M27 10 - 11
(eastbound only)
D3M to D4M 2009
Chopsticks icon.png M40 4 - 5 D2M to D3M August 1991
Chopsticks icon.png M40 1A - 3 D3M to D4M December 1998
Chopsticks icon.png M42 7 - 9 D3M to D4M/D5M (including provision for M6 Toll) 2003
Chopsticks icon.png M56 3 - 6 D3M to D4M 1995
Chopsticks icon.png M60 7 - 12 D2M to D3M 1988 (as M63)
Chopsticks icon.png M60 17 - 18 D3M to D4M 1990 (as M62)
Chopsticks icon.png M60 12 - 15
(clockwise only)
D3M to D4M 1992 (as M62)
Chopsticks icon.png M60 15 - 17 D3M to D4M 1994 (as M62)
Chopsticks icon.png M60 2 - 4
(J3-4 clockwise only)
D3M to D4M 1994 (as M63)
Chopsticks icon.png M60 18 - 19 D2M to D4M 1995 (as M66)
Chopsticks icon.png M60 25 - 1 D2M to D3M 2000
Chopsticks icon.png M60 5 - 6 D3M to D4M 2006
Chopsticks icon.png M60 6 - 8 D2M to D3M with D2M Collector/Distributor Lanes 2006
Chopsticks icon.png M60 3 - 4
(anti-clockwise only)
D3M to D4M 2014
Chopsticks icon.png M62 21 - 22
(eastbound only)
D3M to D4M 1989
Chopsticks icon.png M62 24 - 25
(westbound only)
D3M to D4M 1993 ?
Chopsticks icon.png M62 28 - 29 D3M to D4M 1999
Chopsticks icon.png M62 18
(westbound only)
D3M to D4M
Auxiliary lane from Birch Services
Chopsticks icon.png M62 8 - 9 D3M to D4M 2002
Chopsticks icon.png M62 12
(eastbound only)
D3M to D4M
2 miles west of J12 only
Chopsticks icon.png M73 1 - 2 D3M to D4M 2017
Chopsticks icon.png M74 4 - 6 D3M to D4M 2017

Abandoned Widening Projects

Not all proposed schemes are carried forward. They may be abandoned for a number of factors, such as cost, political sensitivity, or the fact the proposal does not represent a worthwhile investment.

Some of these proposals have been revived as Smart Motorway plans.

Motorway Extents Standard (e.g. D2M to D3M) Notes
Chopsticks icon.png M6 11A - 19 D3M to D4M
or M6 Expressway
Various proposals from simple widening to a segregated toll road between J11A and J19. Lower than desirable traffic volumes on the existing M6 Toll resulted in the abandonment of a segregated toll road, as the expenditure required would not reap the benefits required. There are now various Smart Motorway projects underway to provide four lanes in each direction between the M6 Toll and A556.
Chopsticks icon.png M60 12 - 15
(anti-clockwise only)
D3M to D4M Widening the anti-clockwise carriageway to provide four lanes between the M61 and M62, in order to reduce chronic congestion on this length of motorway. The proposal was abandoned following concerns about air quality and the effect on local properties. A Variable Speed Limit is now under construction for this section.
Chopsticks icon.png M62 18 - 24 D3M to D4M Full widening with replacement of all structures and interchanges to accomodate wider motorway, including building the missing flyover at the junction with the A627(M). The entire distance between Manchester and Leeds is now proposed to be subject to Smart Motorway projects, with J25-30 being the first to open in 2010.

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