The M23 is a motorway in England, running from the south of Hooley in Surrey to Pease Pottage, connected to the south of the significant town of Crawley in West Sussex. Hooley is immediately south of the London Borough of Croydon. Both ends of the motorway form a de-merger from (and merger back into) the A23 which runs from London to Brighton.
Its northernmost part amounts to a spur north of junction 7 of the M25 motorway (junction 8 of the M23) which has spur roads for all directions (is a stack interchange) and intuitively would be numbered 1 as a long, publicly opposed section further to the north was never built. During its length it runs without a serving junction for central parts of Redhill, Surrey, as its next and busiest junction is for Gatwick Airport and it concludes with three, widely spaced out, for Crawley which also serve Horsham and East Grinstead. It cuts through the a gap in the North Downs and a slight gap in the Greensand Ridge, long mainly wooded hill ranges, locally part of the Surrey Hills National Landscape. For the airport to its west, junction 9, has no direct routes to the more rural east; however sweeping to the north-west point of the airport, the M23 Spur gives ready access to Horley, Charlwood and all the northernmost parts and associated out of town workplaces of Crawley.
To the south the A23 is a dualled trunk road so far as the city of Brighton, whereas to the north it sees long single-carriageway urban parts, in the centre of Hooley, north Coulsdon, south Purley, and no traffic-prioritised continuations to reach Inner London, which was the original scheme behind the motorway.
History
The motorway was constructed between 1972 and 1975, at the same time as the southern section of the M25 from Godstone to Reigate (M25 junctions 6 to 8). The current northern terminus at junction 7 runs along most of what would have been its own sliproads for a broad northern continuation. In so doing, these splayed roads split to offer access to the more urban road which the M23 bypasses, the A23, and a flyover above the splayed fledgling motorway still exists for the onward northern continuation which remains unused, between these briefly, but widely, splayed carriageways of the motorway.
thumb|left|Junction 9, looking north
The cancellation of the unbuilt northern section from the M25 in towards Central London has resulted in the A23 carrying the majority of traffic through South London to the motorway. This is largely a single carriageway route, with many level junctions, traffic lights and awkward interchanges. It travels largely through residential areas and means south London reliance on the A22 (hence the Caterham Bypass), running SSE, and A3/A3(M) running SW (southwest).
A new junction (10a) was opened in 1997, between junctions 10 and 11, for access to the new Crawley neighbourhood of Maidenbower. It was financed as part of the development of Maidenbower by the construction consortium. It has only a northbound slip road, no southbound access.
Unbuilt sections
The M23 was planned to relieve congestion on the A23 through Streatham, Thornton Heath, Purley and Coulsdon in south London and was originally intended to terminate in Streatham Vale at a junction with the controversial London Ringways Plan's Ringway 2 (the intended replacement of the South Circular Road (A205)).
In an earlier version of the Ringways Plan it would have continued into central London where it would have met the Balham Loop spur from Ringway 1 (the London Motorway Box) at Tooting. This was dropped in 1967, when the northern terminus was changed to Ringway 2. While a definite route had not been chosen at that time for the northern section, approval was met for the route south of the Greater London boundary at Hooley.
By 1972 the southern section of Ringway 2 had been dropped from the plan, with an alternative proposal that the M23 continue further into London to end on Ringway 1. This was immediately countered in the same year by the Greater London Council (GLC), who announced they would not be building that Ringway, and while the proposals were finally dropped in the mid-1980s, pockets of land that had been acquired were not released by the Department for Transport until the mid-1990s.
The unbuilt six-junctions motorway north of Hooley was due to the refusal of the GLC to finance the project, understanding the ultimately decisive, large-scale opposition to the construction of London Ringways, any network of high speed roads within London.
In January 2020, all smart motorway projects were put under review due to concerns about their safety, during this period no new smart motorways could open. The review was published on 12 March 2020 and required no immediate amendments to the design or construction, however new technology to detect static vehicles is required to be fitted within three years, and a review on spacing of emergency refuge areas was to be carried out.
The fourth lanes were opened to traffic on 2 April 2020 with a temporary 50mph speed limit. Works ran into the late summer to install more equipment, followed by testing and commissioning, before the project could complete and run at the national speed limit.
Junctions
Data from driver location signs are used to provide distance and carriageway identifier information. Where a junction spans several hundred metres (yards) and start and end points are available, both are cited.
{| class="plainrowheaders wikitable"
|-
!scope=col|County
!scope=col|Location
!scope=col|mi
!scope=col|km
!scope=col|Junction
!scope=col|Destinations
!scope=col|Notes
|-
|rowspan="2"|Surrey
|rowspan="2"|Merstham
|17.0<br>17.5
|27.4<br>28.2
|7
| - Croydon
|Road continues as A23 to Croydon
|-
|19.0<br>19.3
|30.5<br>31.0
|8 Mersham Interchange
| - Heathrow, Watford, Dartford Crossing, Reigate
|
|-
|rowspan="4"|West Sussex
|Horley
|26.5<br>26.8
|42.7<br>43.1
|9
| - Gatwick, Redhill
|Terminus of spur towards Gatwick
|-
|rowspan="3"|Crawley
|28.5<br>28.6
|45.8<br>46.1
|10
| - East Grinstead<br>
- Crawley
|
|-
|30.3<br>30.6
|48.8<br>49.2
|bgcolor=ffdddd|10a
|bgcolor=ffdddd| - Crawley
|bgcolor=ffdddd|No exit from M23 Northbound, no access to M23 Southbound
|-
|33.1<br>33.4
|53.3<br>53.8
|11
|Pease Pottage services<br>
- Brighton, Crawley<br>
- Horsham
|Road continues as A23 to Brighton
|-
;Coordinate list
The M23 is the only motorway in Sussex.
References
External links
- www.cbrd.co.uk
- Motorway Database – M23
- History of the aborted M23 plan
- The Motorway Archive – M23