Region: South East
M27. The South Coast Motorway, M271, M275 and A3(M)
The M27 was developed from the long-standing route for a new South Coast Road established in the late 1930s, when a new dual carriageway route with at grade junctions was identified by the County Surveyor of Hampshire and used for development control purposes. Residential developments after the Second World War at Chilworth (north of Southampton) and at Paulsgrove (near Portsmouth) were restricted to allow room for a new road. However the restriction of industrial development south of Eastleigh (Southampton) airport was broken during World War II to allow for a large factory extension over the route for the manufacture of Spitfires.
The M27 runs from Cadnam, west of Southampton, to the north side of Portsmouth. Design work was started again by Hampshire County Council on behalf of the MoT when, in 1967, a team of Hampshire County Council engineers who had been working on the design of the M3 London-Basingstoke motorway were transferred to a special office in Southampton. It was subsequently taken over by the Hampshire sub-unit of the South East Road Construction Unit and on the privatisation of the RCU the work was completed by Mott Hay & Anderson (as known then) under the overall supervision of the SE Regional Office. Fortunately for all concerned this was not as complicated as it might appear as the post-war work was carried out essentially by the same people, albeit employed by different organisations.
The principal changes from the early South Coast Road plans included an increase in land take for the dual 3-lane motorway standard and a new vertical alignment to permit the grade separation of side roads and junctions. The Westerly termination of M27 at Cadnam followed an understanding with the Verderers of the New Forest that the motorway should not run through the Forest. The eastern termination of M27 at Portsbridge joined the improved A27(T) which had been routed southwards out of residential development by construction of the Havant and Farlington Cosham bypasses.
To the east of M27 the six mile length of A3(M) from Horndean to Bedhampton takes the route of A3 out of the built-up areas between Horndean and Cosham and was presumably designated as motorway because at that time (1976) it was assumed it would be connecting directly to the M27 motorway. It was completed in 1979. Initially the M27 was destined to be taken at least as far as the Bedhampton junction and, apart from the different coloured signs, the motorist will probably be unaware that it did not happen. However the land acquired for this stretch of the motorway was not quite wide enough - by less than a foot - and the Chief Highway Engineer of the day, quite rightly if a little pedantically, ruled that it didnt conform to motorway standards and must therefore be an all-purpose trunk road.
In addition to the East West motorway route, urban motorway links were proposed into the city centres of Southampton and Portsmouth. The M271 Nursling Spur linked to Southampton's western docks and the Waterside parishes. A second link was proposed at Stoneham known as the Portswood link motorway which would have become the main access to the city centre and eastern docks. North of Southampton new links at Chilworth and Bassett were included to re-route all trunk road traffic from the north onto M27 in order to remove external traffic from the main city access along the tree-lined "The Avenue" and its adjoining park.
At Portsmouth the interchange included a link northwards to A27 at Cosham and M275 to the South which was planned as the new principal access to the city centre. The whole of this interchange was located within Portsmouth Harbour and required major land reclamation, which is described later.
Between these extremities M27 followed the South Coast Road route except for the section between Hedge End and Fareham which was re-routed southwards in order to provide short links to A27 at Windhover and Parkgate. These were required to serve planned major industrial and residential developments at Parkgate and Fareham Western Wards. Thus, it can be seen that, in addition to replacing the inadequate A27 trunk road, M27 was a vital part of the plan for the development and expansion of South Hampshire.
Draft Statutory Plans for the 30 mile route were published in 1968 and were generally welcomed as demonstrated by a three-week Public Inquiry which dealt with mainly local issues. The Minister of Transport confirmed the proposals in 1970 with the exception of the section north of Southampton which was the subject of a strong objection from the Ford Motor Company who had taken over the aircraft factory. The existence of the wartime legal agreement to protect the route for a new road was not sufficient justification for dissecting a motor vehicle production plant.
A new somewhat tortuous route was developed that avoided the factory by skirting Eastleigh Airport. This was confirmed in 1971 in spite of counter objections by the Airport operator regarding the consequential effect of reducing the runway length. Unfortunately the revised route also ran through a Chapel of Rest and remains were removed to the nearby new Southampton crematorium.
Further difficulties followed north of Southampton when, in 1973, the newly elected City Council abandoned the Portswood Link motorway: its construction would have required demolition of over 500 houses. Trunk road connections were then added for "The Avenue" to remain as the principal access from the north, and a much scaled-down conventional interchange was adopted at Stoneham to serve the Airport and to join to a new link road connecting to the existing roads at Swaythling. The Statutory Procedures to implement these changes were completed in the 1978-80 period.
The rapid progress of the statutory procedures for the eastern and western sections of M27 permitted construction to commence in autumn 1971, only three years after the commencement of the motorway design study. The first works were the advanced construction of earthworks in Portsmouth Harbour, described below.
Four further construction contracts were awarded in 1972. Three for the Cadnam to Chilworth and Windhover to Portbridge sections of M27 at a total tender cost of £38 million for 14 miles of main route. These works were completed by May 1975 in spite of major engineering difficulties arising from the low quality fill materials found in several major cuttings and a three-month curtailment of work due to the Nationally imposed three-day working week following the 1974 oil crisis. This oil crisis led to the Ower Chilworth contractor changing from the originally intended asphalt surface to a concrete pavement (brochures describing these construction contracts are included).
A fifth contract was left in 1979 to extend the motorway to Hedge End. This section was four lanes wide because of the close spacing of the interchanges and lit originally by catenary lighting, but this was later abandoned as it proved to be unreliable.
The M27 operated as these two separate entities from 1975 to 1984 whilst these various issues north of Southampton were being resolved. This delay coincided with a national pattern of slower progress in the completion of the statutory procedures as the public became more involved and sensitive to the environmental effects of heavy traffic. Construction of the M27 "missing link" commenced in 1981 with the award of two construction contracts at a tender cost of £38 million.
The motorway has 100 bridges which include major structures over the River Hamble and at Tipner in Portsmouth Harbour. The noise protection barriers at Paulsgrove were one of the earliest to be constructed following the introduction of Statutory Noise Regulations. Both hot rolled asphalt and concrete pavements were constructed in a somewhat random way as the economics of these two forms of construction were very finely balanced. A service area was constructed at Rownhams, west of Southampton, and a reserve site identified near Park Gate but never progressed.
Construction of M27 has led to the attraction of substantial development close to the motorway and along the relieved A27 East of Southampton: including the building of the IBM UK headquarters within the land reclamation at Portsmouth: the establishment of a major "out-of-town" shopping centre at Hedge End: completion of the planned developments west of Fareham: development of a cross-Channel ferry terminal at Portsmouth: the refurbishment of Southampton (Eastleigh) as a significant regional airport: the establishment of a major container terminal at the western Southampton docks and the national air traffic control centre at Swanwick.
The M27 runs for 30 miles between Cadnam and Portsbridge. However major trunk road improvements were carried out to the A31 through the New Forest and westwards towards Poole, and eastwards on a new route for A27 from Havant to bypass Chichester, so that M27 now forms the central section of a 60 mile length of high standard dual carriageway road fully justifying the original concept of a South Coast Road. The M27 has links northwards to M3 at Chilworth (finally completed in 1992) and at its eastern end by A3(M) to A3, thus linking South Hampshire to the national trunk road and motorway network.
Chalk fill at Portsmouth Harbour - use of belt conveyors
The motorway interchange with the M275 was to be sited on embankments within Portsmouth Harbour.. These embankments required 4 million cubic yards of fill, approximately half to be obtained from the M27 chalk cuttings at Paulsgrove and used to form perimeter bunds. The remainder was to be pumped dredged material placed between the bunds. It had been decided that these works should be constructed by an advanced earthworks contract as they were larger in scale and complexity than the earth moving generally included in the road construction contract.
Two main obstacles lay between the source of the chalk fill and its deposition. Firstly the Paulsgrove housing estate. A narrow gap had been left in the housing for construction of the motorway (a good example of some farsighted planning) but to transport this volume of chalk through a dense housing estate could be environmentally damaging for the residents and there were safety concerns as many young children lived on the estate. Secondly there was the logistical problem of transporting this material across two very busy roads, the A27(T) and Allaway Avenue, and a railway. Clearly these obstructions were formidable.
The road research laboratory (RRL) had been looking at belt conveyors as an alternative means of earth moving for some time and it was decided that this offered a possible solution. A contractor (John Laing) with experience of using conveyors was chosen, a target price contract was negotiated (the work was not suitable for competitive tendering) and the conveyor was procured directly by the Ministry of Transport.
The curvature of the motorway restricted the length of individual conveyor units as they could not be located outside the boundary of M27 (as RRL had assumed in their studies). The conveyor consisted of ten separate units each individually powered by an electric motor so there was minimal noise generation. At each turn the chalk dropped from an elevated end section on the next conveyor.
The conveyor was erected and brought to an operational state without difficulty. However it was soon apparent that the characteristics of the chalk leaving off the last conveyor had changed from the original reasonably hard lumpy nature, almost to a slurry which on deposition resembled "porridge". This change was due to moisture locked in the matrix of chalk being released as the material bumped its way along the conveyor units. It was impossible to doze the material away from the end spreader to form the embankment. Eventually the problem was solved by manufacturing an new spreader with a much longer boom permitting material to be placed in locations where it could be left to dry out before being spread and by using smaller plant than originally intended. The quiet operation of conveyors permitted earthworks to be carried out at night, and this helped to make up the lost time.
The difficulties of spreading the chalk had a material effect on the final cost of the operation but even so the use of the belt conveyor in this location proved satisfactory and a large volume of chalk was moved safely and with minimal disturbance to residents of Paulsgrove and the users of roads and the railway.
When the main construction contractor moved onto site he found considerable difficulty in excavating drainage trenches in the deposited chalk which had set to a hard rock-like manner, clearly demonstrating that the early difficulties had been resolved.