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Title: Design on the motorway

Pages: 42-49

                        

Author: Ian Breach

Text: Design on the motorway

Britain got off to a late start in motorway construction, even though the word was used as long ago as 1924 and a national motorway plan was in existence by 1944. Now 1000 miles are expected to be operating by the mid-70s. How successfully have they been planned, and what is the future of road communications in this country? Ian Breach assesses the record to date and the prospects

For more than a century and a half - a span covering the Industrial Revolution proper - the construction of new roads in Britain was arguably the least advanced of all the communication technologies so vital to that period. It fell well behind the colossal economic and engineering investment devoted to rail and waterway development and, from a capital outlay point of view, was even eclipsed by the setting up of a wireless-telegraphy system towards the end of the nineteenth century. Apart from the building of industrial access roads and residential streets, the highway network was essentially unchanged from the old pack and coaching routes. Even maintenance and improvement of these had been neglected by comparison with advances in other civil works, and when the motor vehicle first appeared in any numbers, they had to be accommodated on roads that, in many cases, were unfit even by horse-drawn standards.
Official awareness of the need for an urgent and massive programme of building roads specifically for motor traffic emerged surprisingly early. In 1900, the Prime Minister, Mr Balfour, was advocating "great highways . . . confined to the carriage of rapid motor traffic'', and by 1920 - when congestion in the large cities had reached a desperate level - firm recommendations for a motorway network existed. The word itself was first used in Parliament in 1924, when a construction Bill was introduced: it was to be 25 years before a similar Bill became the Special Roads Act, 1949. Clearly, the intervening years had set Britain some more pressing problems than the construction of roads, but two factors became decisive. The first was ministerial recognition of the part Germany's autobahnen had played in that country's early strategic gains (an advantage recognised in the US before the war by actually naming the American network ''Defense Highways'').

(caption)
Sprawl and spread: Opposite top, heavy-handed first stage of M1. Top, paths of glory - opening of the first autobahn section, 1936, between Munich and Landesgrenze. Above, Early Italian style in Naples. Above right, American Midwest monotony on a 1955 Interstate Highway. Right, Fourleaf freeway - the classic American in intersection


The second was the inexorable rise by volume of traffic. By the time Britain had formulated a national motorway plan, in late 1946, Germany already had close on 2500 miles open to traffic, America was well ahead with construction of a
41 000-mile network, and Italy - the first country in the world to lay roads down exclusively for motor traffic - had more than 300 miles: in Tripoli, it had constructed 1000 miles of motor road, which was to prove exceedingly helpful not long afterwards to both Rommel and Montgomery. There was a further decade of delay before any literally concrete proposals were made. These came with transport Minister Lennox-Boyd's announcements, in 1953, of route plans for parts of what were to be the M50, M6, and M2.
On February 2 1955, John Boyd-Carpenter, the succeeding Minister of Transport, included the London-Yorkshire motorway and the Birmingham-Preston motorway in an expanded programme of schemes amounting to contracts worth £147 millions over the following four years. On 12 June 1956, work was begun on the Preston bypass section of the M6. Most of the early motorway construction in fact produced little more than bypasses, and it was not until 1959 that it really picked up, when 73 miles of the M1 were opened. After that, building went in spurts, with a high point of nearly 100 miles in 1963 and a disastrous low of eight miles in 1964, which was caused mainly by the appalling weather in the winter of 1962-63. Throughout the '60s, construction was affected - as it still is - by sharply increased costs on the one hand and strained national budgets on the other.

Britain's future network

By 1968 Britain had a fairly well developed plan for a motorway network to take us towards the end of this century, with 1000 miles to be completed by the mid-'70s. The present plan is for a 3500 miles high-quality trunk road network by the early 1980s with up to 2000 miles of motorway.
What will this network look like? What should it look like? Obviously, the backbone has to bear a strong resemblance to that of the Victorian railway system, linking ports, major cities, centres of basic industry, and so on. But in the last quarter of this century, other factors are bound to play a part. Areas of intense regional development - mainly to the west and - north - will make new demands on communication links, and it is crucial that decisions on whether these links ought to be predominantly road, rail, or air be made more quickly and with greater care than has been the case so far. Major increases in traffic and marked shifts of distribution will occur for two chief reasons - commercial development and tourism.
As examples of the first, the opening up of east-coast ports, like Immingham and the Humber estuary for more efficient trading with Europe, the container revolution, and the expansion of North Sea fishing and mineral exploitation have all suffered from and aggravated a lack of good road (and rail) routes. The oil industry's current activities off the coast of North-east Scotland are a prime example of a region now committed to colossal traffic increases but which was never included in the national trunk-route network. The growth of commercial traffic in areas where it had not been allowed for in the existing road programme has been accompanied by an inordinate rise in the number of private cars, many of which are clogging the same regions. Thus, private traffic passing through Kent on its way to the Channel ports has increased by more than 400 per cent over the past decade: together with heavy goods traffic, it is causing the most painful problems in a region that is still waiting for motorway relief. Its residents' threats of sabotage are growing more and more serious (whether their children would regard the provision of motorways as an answer is, of course, very much open to question).
In addition to changes of this sort, there are three other quantities to be included in what, for the motorway planners, is an equation of nightmares. The first concerns human population trends: if State intervention in planning for population growth and shift, development of new towns, and location of industry is projected from its present extent towards the next century, several points of heavy urban concentration will lie outside the motorway map, while others - to take Milton Keynes as one prime instance - will exacerbate the axis effects of a major road (the M1) joining two major cities (London and Birmingham).
The second and third additional quantities concern transport itself. Firstly, what are likely to be the major technical changes? If APT technology is exploited as fast as British Rail would like it to be, we could see a substantial transference of road traffic to rail between large cities and ports. At a less advanced level, developments in high-speed local transport, using Cabtrack, tracked hover vehicles and similar hardware, might well bring about a significant reduction of demand for interurban motorways. There appears to be no urban concerted official view on the choices. Together with these possibilities, the final question to ask would be about the political and social trends. Mobility will be affected not merely by price and availability of roads and vehicles, but by our society's overall view of what we want from our environment. A growing number of motorway schemes look likely to be lengthily delayed and possibly even abandoned in the face of public opposition. To a limited extent, these effects will be mitigated under the recently announced plans in the DoE's White Paper ''Development and Compensation- Putting People First", in which it is proposed to make £70 million available yearly for those affected by major planning decisions. Nottingham has thrown out a ring-road scheme; other cities are considering it as a possible anti-blueprint for their own roads; London's urban motorway plan recedes in likelihood as it grows in estimated cost; and Essex prepares to cope with a motorway scheme for what might, on completion, prove to have been an unnecessary airport. Indeed, changes in air-transport could be a major influence on the roads we need for the twenty-first century, though the environmental objections to short-haul and helicopter air traffic between cities are likely to prove even stronger than the protests against major road development.
The first generation of motorways, then, is about to be completed in Britain. To call them a mixed blessing would be a mistake: they have been a costly blessing, for the political, social, and economic agonising that has attended their construction so far has been heavy in any terms. What of the physical benefits? They have undoubtedly changed travel patterns for a very large number of commercial transport operators and private motorists. Where a haulier allowed two - and sometimes three days - in the '50s for goods to be carried from London to Edinburgh, average speeds can now be maintained that cut the journey to a day. Relatives who rarely visited one another can now make familial pilgrimages: but it is necessary to qualify that advantage by noting that car ownership has more than doubled over those 12 years. They might well have made the journeys anyway. And families have increasingly been distributed, geographically, in a way that is part of the social pattern in which motorway development is rooted.
It is possible, using figures prepared by the Transport and Road Research Laboratory, to quantify the cost benefits in terms of time saved: a dubious exercise, especially if we accept that a major problem of the '80s and '90s might be the satisfactory filling of newly-found leisuretime. More relevant, perhaps, might be the real savings in terms of accidents. Motorways' gentle curves, long lines of sight, the absence of intersections, and generally good signalling technology have all combined to reduce the casualty rates by something approaching 25 per cent on those for the best three-lane trunk roads. In fact on certain sections, where traffic has increased by 32 per cent (eg, the M6 from 1965-69), accident rates for the total traffic handled in the region served have fallen by three times that amount. Motorways are irrefutably safer than conventional roads for the carriage of conventional motor traffic.
This is in spite of the fact that motorway speeds have been higher (even after the nationwide 70mph limit) than on other roads; in spite of the fact that safety fences were not regarded as a necessity until 1971; in spite of the fact that motorway collisions tend to be significantly more serious, in terms of injury and accident damage; in spite of an intransigence towards motorway lighting (finally accepted as a sensible essential for many areas in 1972). On the motorways themselves, driving had become easier (and safer), largely through much-improved alignment and landscaping.
As far as the environment is concerned, the effects have been mixed. It is true that a number of towns have seen their congestion, noise, pollution, and road-safety problems alleviated by the appearance of nearby motorways. Stafford inevitably comes to mind as one place where this has been true, even if only in a short term sense. Others, like Lancaster and Preston, have seen at least some of the enormous pressures taken off an overloaded local and urban road network. But in some towns and cities, the situation has worsened, where motorways plunge into the heart of the conurbation, bringing either acute congestion or accelerating the process of decay (or- as in Birmingham - combining both effects at once). London, Leeds, and Manchester can all be said to have suffered from an overdose of motorway traffic which they have no room to accommodate.
Others have suffered. Land has been acquired on terms, both philosophical and practical, that have appeared to be cruel. Motorway neighbours have suffered from the inevitable effects of noise and visual disruption. Overstrained routes have been further stressed by being unlucky enough to be links between motorways: the A5 between Brownhills and Gailey suffered almost unbearable punishment for nearly 10 years as motorway traffic funnelled itself from the M1 to the M6. And not every motorway was a blessing even to those who used it. The M1 was extensively prone to surface damage, necessitating frequent repairs and lane closure. Service areas were unable to cope with demand. There was unsightliness and inadequacy. No one had thought enough about an age of day-trippers who would want scenic enjoyment, ease of travel, food, shopping, and travel information as part of the whole motorway package. If it has taken a long time to decide that we should have a motorway network, it is taking even longer to decide what we should do with it.

(caption)
Opposite centre, Tunnellig out of Italy - final stretch of the Chiura-Bolzano autostrada, due to open next year. Left, Aosta aorta. This page top, Schwarzwald Landschaft - modern autobahn south of Bad Hersfeld; above Britain's master plan

Planners learn the three-lane rule

Design standards for urban and rural motorways in Britain have not undergone any drastic revision over the past 10 years. Carriageway capacity. alignment and cross-section specifications for the latest motorways are calculated using the same basic assumptions. For the first, it seems to be the Department of Environment's policy to plan for a growth in traffic of between 2 and 3 per cent a year and to work on peak flows of between 1000 and 1500 vehicles per hour per lane. Clearly, compromises have to be made, and, in designing any motorway, the Department and local authority for both interim traffic distribution and for the ultimate distribution when that motorway is part of a completed network. Thus, layout at - for example - Worsley braided interchange; construction provides for dual three-lane carriageways but allows eventually for the addition of a lane at the interchange when all the proposed local motorways are in operation.
In this, the DoE has learned a hard lesson from the M1, which was conceived at a time when traffic forecasts were virtually no more than hopeful guesstimates. Where possible, all rural motorways are being built with three lanes - but even in the '70s, immediate economic pressures may prevent anticipatory construction: the DoE can, however, make provision for future expansion. On alignment, the standards first used are largely the ones still prevailing. It is interesting that they were based on a design speed of 70mph long before the speed limit was introduced, but the DoE points out that speeds of well above the limit would come within the safety margin provided by the fundamental relationship set down for curvature and centripetal vehicle forces. These give a minimum sight distance of 950ft in both vertical and horizontal planes and appropriate radii of curvature, ranging in practice from 3000ft on level ground to 60 000ft at summits. Gradients are still kept to a maximum of between three and four per cent, with signed "crawler" lanes provided on particularly long climbing grades.
Apart from a slight reduction in width of verges in 1967, the Ministry of Transport cross-section is roughly the same as it was 10 years ago: 12ft lanes, a 13ft central reservation, 91/2ft hard shoulders, and 5ft verges (which accommodate drains, electrical and emergency telephone services, safety fences, and signs). Within this specification, the structural characteristics of motorways have gradually been revised in keeping with advances in materials technology and the science of soil mechanics. Motorways are now constructed in flexible bituminous, semi-flexible and rigid pavements. Poorer quality sub-base materials have been found to provide adequate support where much more costly materials were previously used - an example of the ways in which some early motorways were over-engineered.
An ideal surface has yet to be developed, chiefly because there are so many conflicting or overlapping requirements. Measures to improve skid-resistance invariably worsen the noise and vibration characteristics; some materials that promise a higher durability can be prone to frost damage; semi-pervious surfaces - being experimented at the moment in the Tebay Gorge section of M6 in an attempt to minimise spray problems - might significantly reduce the working life. In these, as in so many aspects of motorway construction, the needs for compromise are seemingly endless. Maintenance, in fact, has been one of the road authorities' lesser problems, in spite of a public impression to the contrary. Many of the lane closures in the last year or so have been necessitated by the erection of central reservation barriers, a safety measure adopted nationally by the DoE after a chain of crossing accidents in 1970 and 1971. In addition, the first stretches of rural motorway, such as the M1, are well into the predicted period of pavement maintenance after having carried substantially more than the predicted traffic.
The actual construction work on motorways has developed in both scale and technique.

(caption)
Mechanicals and others: (above and right) infrared surveying equipment using laser beam to establish lines and levels; centre, Caterpillar Compactor; below left, CEGB cable bridge for fixing cables while the road is kept open; below right, automatic grader and leveller

Planners have tended to go for simpler but more effective methods of network analysis: where charts once showed every stage from proposal down to the last lorryload of turf, engineers are now using a time-based version of PERT (Programme Evaluation and Review Technique). Called Cascade, it enables everyone concerned to rapidly assess progress and update operations. Contracting procedures too have evolved, the optimum size of contract reducing from an average of 10-15 miles to one more often between seven and 10 miles: it is now the norm for contracts to be completed well within schedule, a lesson which could well be noted in some other sections of the construction business.
A major development has been in plant capability. Using or adapting machines and techniques from abroad (mainly the US) earthmoving capacity has been vastly increased. Motorised scrapers - which themselves now handle 40cu yd where they used to carry no more than about 15cu yd - have largely taken over from tractor-crawlers. Conveyor belts have been used for earthworks, aggregates and sub-base handling, enabling work to be carried out in bad weather, reducing local disturbances from heavy-lorry transport, and maintaining flow - which has been a limiting factor in the speed of construction. The use, where-ever possible, of local wastes - colliery shale, gravel pits, and other industrial spoil has been a more frequent feature - and, obviously, an economic one - of the last five years' work.
Conditions are markedly different to those in the US and Italy, where the seasons are kinder to earthmoving and foundation work, but from both these countries, plant and operational techniques have been borrowed for tackling jobs on a grand scale. Pavers are now used that can lay the whole of a 36ft carriageway in one traverse using roadside guidewires (there is a 45ft version available), and the absolute speed of laying has quadrupled during the first generation of motorways: it is now possible to move at 800-1OOOyds per day. In fact, advances like these have had the effect of cutting unit costs rather than massively speeding up construction, for progress is limited by the earthworks and bridge construction. Some contractors apparently prefer to leave bridges until the carriageways have been built, although there has been a tendency for structures like bridges to be built before the final road contract is let.
Bridges were for long something of a Cinderella in the motorway business. Not many outside the bridge-building profession took much interest, and those within it had little time - either literally or figuratively - for aesthetic considerations. But the public made no secret of its dislike for the early M1 bridges, mainly ugly, lumpen structures. The DoE points out that these were erected at a time when rapid building and erection was the main criterion - especially true of the southern section of the M1, which was, after all, largely the engineering equivalent of a Conservative Party political broadcast.
But the designers and engineers responsible for these bridges were often the same as those who later worked on some of the really attractive structures on M1 north and M6 that have deservedly brought the DoE credit from the public and awards from the Civic Trust. Developments in the use, first of prestressed and then of precast "factory made" concrete spans opened up possibilities, and the overall effect has been visually much happier. In fact, there are still comparatively few stock bridge designs, though graceless clichés are still to be found, of which many observers cite the M62 cross-Pennine ones as outstandingly poor.

Comprehensive sign language

It has taken a relatively long time for motorways to be regarded and treated as a complex communication network in itself: the lack of physical connections has not helped this concept. But as the system takes a whole shape, so a plan for communications has evolved. Initial work concentrated on the preparation of colour, size, and symbol schemes, largely through the famous deliberations of the Worboys Committee. With practically no exceptions, its recommendations were accepted and are now adopted almost internationally. Blue destination signs, yellow emergency vehicles, white lane separation markers, green and red edge reflectors, blue and white countdown posts present a coherent and measurably comprehensible ideographic language to the user.
By 1975, the system will have built into it a signal and telecommunication network operated from five control centres, the first two of which opened this year. These are at Westhoughton, Perry Barr, Scratchwood, Almondsbury, and Hook. The last three will be in operation by the spring of 1973 and, with one possible additional centre in Yorkshire and the old police control west of London in Heston on the M4, will collate and distribute information for the whole British motorway network. Response times of minutes will enable information on speed, lane closures, and diversions to be flashed to the new overhead signal gantries almost as fast as conditions warrant. They will be supplemented by signed displays warning of distant conditions and difficulties.
Hazard warning lights are being discontinued. They were never really useful, often misleading and unreliable, and a source of constant irritation to motorists and police alike. The telephone system will be strengthened, and its links with central control points should make it possible to process emergency information far more quickly than it has been in the past. The DoE is also working on ways and means of differential signing to relieve pressures at congestion points, or to distribute traffic more efficiently at interchanges where ''peeling-off peaks'' occur. The approach is very much nowadays one of "we are still learning" - an open-minded response to criticisms of gantry design, suggestions for re-signing particularly tricky sliproad exits, a greater willingness to listen to popular recommendations.
The DoE also has to anticipate vehicle developments. Anti-dazzle screens, headup displays, and separation-distance systems are all likely to find their way into production models within the next five to 10 years. Noise levels will be cut if the motor industry keeps its promises - possibly negating extensive acoustic screening at places like Gravelly Hill and other urban locations. Flow densities may be reversed in some cases - a possibility that partly bears out the German practice of going for a generally denser, tighter network of two-lane carriageways.

(caption)
Landscaping the unopened sections of the M5 south of Bristol. Pebbledash prospect, culvert concept

Expanding the service concept

One of the most criticised features of the British motorway network has been its service areas. The first ones built - Newport Pagnell and Watford Gap on the M1 - were, without a doubt, misbegotten, inadequate, ugly messes. Carelessly sited and thoughtlessly equipped, they have become textbook examples of how not to build service areas. Since they were constructed, of course, costs have risen not merely as a reflection of rising prices but also through the determination not to repeat the mistakes made in these early areas: when they were put up, the cost to the Government lay somewhere between £150 000 and £200 000. It is now more like £600 000 - plus developers' costs of between £500 000 and £1 million - figures which exclude the cost of land. The 10-13-acre solid development of the first ones has given way to the kind of area at Leigh Delamere on the M4 (see DESIGN 282/40) with a carefully landscaped 40-acre plot.
Inevitably, the demand for services was underestimated; the type of demand was misjudged. And some catering firms came a cropper, providing waitress service, for instance, where it was not required, taking no account of the costs of damage and - increasingly - of vandalism, and making too few provisions for the rapidly growing number of commercial drivers using the motorways. This is recognised in the plan to build a commercial-only service area (motorists will be admitted) at Rothersthorpe, half way between Watford Gap and Newport Pagnell. The split between tourist and commercial traffic in Britain does not reflect Continental experience, where the bulk of catering is for private motorists.
There are no plans for developing motorway service areas as leisure points, partly because developers are understandably wary of committing themselves to heavy expenditure, partly because it has been an unwritten rule not to provide overnight accommodation, caravan parking space, or sophisticated restaurant facilities. To some extent, this is fair enough: compulsory land and property purchase orders are painful enough to execute for the roads themselves without extending acquisition for the erection of strictly unnecessary buildings. The DoE has retained some extra land at places - such as at Killington and Tebay West on the upper M6 - for possible expansion of these from simple petrol points to full-scale service areas, but it remains seemingly indifferent to the concept of providing much more than char and wads for the hoi-polloi and ignorant of other countries' efforts to do much more.

(caption)

Messagemakers: opposite left, control centre at Perry Barr, Birmingham Below left, Britain's first motorway signalling scheme, installed on Severn Bridge (M4) in 1968 Above, early tv monitor on a US freeway (John Lodge, Detroit)

Above, Not in Blackpool but in sight of it: Forton service-area restaurant on M6 Left, ye olde eaterie: restaurant at Trowell, M1

Below, Seventies Sawtooth: neat functional lines for maintenance depot near High Wycombe, M40, a good example of the careful and sensitive vernacular style of Bucks County architect's department, under Fred Pooley. The scheme comprises a maintenance depot, garages, a salt store and hoppers. The main depot building is a simple north light structure, clad with warm brown galbestos sheet and plum-coloured facing bricks. The complete scheme, including six houses for permanent staff cost £150 000, nearly a third of which was spent on cutting and filling the steeply contoured site

Bottom, answer to a motorist's prayer - The church of San Giovanni at a service area on Autostrada del Sole in Italy

 

 

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