Title: Motorways that take to the moors
Pages: 58 - 65
Author: David Rowlands
Text: Motorways that take to the moors
Two recently completed stretches of motorway in the North of England open up areas previously noted for bad driving conditions and traffic jams. A six mile section of M62, the road which will eventually link Liverpool with Hull, traverses the worst part of the Pennines separating Manchester and Leeds; and a 32 mile section of M6 extends the Birmingham-Scotland motorway north of the Lake District, replacing the notorious A6 Shap Fell road. David Rowlands discusses engineering, environmental and social implications. Photographs by Homer W Sykes
(Caption page 59) Left: construction of the Scammonden Dam carrying M62, the first joint motorway/dam project in the world, across Black Brook valley. The immense scaffolding required to build the Scammonden bridge over Deanhead cutting dominates the horizon. Below: the completed 700 yard dam, for Huddersfield Corporation, and the motorway seen through Scammonden Bridge from the highest point on Deanhead Cutting.
M62 across the Pennines
There's an element of gambling in the contemplation of a trip from Leeds to Manchester during the winter months the risk of overtaking slow lorries on sharp gradients, the chance of sudden fog banks, black ice patches, and the threat of roof-deep snow. On the map it's only a small step from Yorkshire's industrial belly to the Lancashire counterpart; in reality, the peaks and moors of the Pennines top 1500ft, separating the ancient rivals quite as well as they have over the centuries.
Few projects break the east-west alienation more effectively than M62 - a motorway that will link the ports of Liverpool and Hull, the Manchester and Leeds - Bradford conurbations and the M6 and M1 motorways. Surveying began in November 1961 and three sections are now completed. One, north of Manchester, links with M61 and in Yorkshire the maze of factories and power stations has been cut through between Gildersome and Lofthouse on M1. The other section slices from the Lancashire boundary, at this point over 1000ft high, down to the heavy woollen area at Outlane near Huddersfield. In terms of grandeur and innovation, the engineering of this six-mile section dominates the whole motorway.
In this short stretch the motorway climbs from the Outlane interchange with A640 up to Pole Moor, where it enters a series of small cuts with attractive stepped rock slides. The panorama opens out as the road turns on to Scammonden Dam and the new lake with its distinctive valve tower close to the road on the eastern bank. From this point the Deanhead cutting and Scammonden Bridge are clearly visible. In the cutting there are views of Blackstone Edge carrying the county boundary and the Pennine Way and, rounding a bend, the road stretching up to Windy Hill across Moss Moor. Here the carriageways split on sidelong ground and curve around a farmhouse, its chimney smoking and hens clucking as though nothing had happened in the last four years. On
(Caption page 60) Map shows the six-mile section of M62 over the Pennines - peak height 1200ft. The valve tower in the new reservoir (left), designed by Rofe, Kennard & Lapworth for Huddersfield Corporation, is connected to the east bank by a footbridge supported on a second tower (above).
Moss Moor 650,000 cubic yd of excavated peat has been dumped on surrounding mountain tops, neatly reversing the natural process of erosion and toning down their otherwise harsh and angular outlines.
At Windy Hill the motorway reaches its highest point of 1220ft and heads downhill a little to the interchange with the A672, Halifax-Oldham road. Beyond the finished section and the Yorkshire-Lancashire county boundary is the Pennine Way Bridge spanning the Windy Hill cutting and, for the moment, a sea of mud leading down over Low House Moor to Milnrow, a section due for completion at the end of this year.
The siting of the Pennines crossing point was restricted, by development and topography on the Lancashire side, to a narrow patch of land between the A672 Ripponden-Oldham road and the heights of Blackstone Edge. Yorkshire's choice was between a high level route, rising to about 1400ft, and a slightly lower one at 1200ft. The decision to plump for the lower one was largely dictated by the results from small meteorological stations set up in the area during the winters of 1961 and 1962. Manned by West Riding County Council employees or local farmers' wives, the stations were equipped to measure maximum and minimum temperatures, daily and total snowfall and
(Caption page 61) Scammonden Bridge (left and below), about 21 miles from the Outline interchange, carries A6025 across Deanhead cutting. During its construction 70 miles of scaffolding were required to support the 656ft deck 120ft above the motorway level. It is the largest fixed arch bridge in Yorkshire. The stepped sides of the cutting have 15ft shelves which act as snow catchment areas preventing dangerous drifting onto the carriageways.
visibility. From this massive collection of data the Meteorological Office confirmed that the low level route suffered 30 per cent less fog, 10 per cent less frosts and 20 per cent less snow. Wind studies showed that the high level road would be swept 32 times more frequently by 25mph winds and 7 times more frequently by winds over 39mph.
One other consideration influenced the final decision on the motorway line: nearby Huddersfield wanted more water and had already proposed a dam across the Scammonden Valley. Legally, dam and motorway builders aren't supposed to get together but a special Bill in Parliament allowed Huddersfield Corporation and the West Riding to make considerable cost savings by building a big enough dam to carry the motorway on its crest. As far as they know this dualpurpose construction is unique in the world.
Farmers apart, the only inhabitants of this part of the hills are sheep, which are a menace to traffic on normal roads, let alone motorways - hence the need for cattle grids on the slip roads. But studies indicated that even the most mercurial of them couldn't breast a 5.5ft fence, although lambs might wriggle through quite small chinks. Fences also cause snow-drifting if they are of sufficient windward area to cause air turbulence on their leeside. The solution, a plastics coated tensioned wire mesh, was designed by the Darlington Fencing Company. Lambs are barred by progressively smaller mesh sizes at the bottom of the fence and its grey colour, recommended by the Royal Fine Arts Commission, effectively merges it into the bleak moorland background. The fence posts, set in concrete footings, resemble small triangular pylons. The wire rope safety barrier supported on slotted steel posts was also selected for its minimal influence on snow drifting.
However well the road was sited snow would still be a problem, for in an area of comparatively low snowfall drifting from adjacent land extends its period of nuisance. The 150ft deep cutting at Deanhead would fill with unmanageable depths unless some way of profiling its banks to channel the snow away could be found.
The design of this particular cutting was carried out on a scale model in the National Physical Laboratory's wind tunnel. Using balsa wood powder to represent the snow, engineers obtained some idea of where to expect drifts. Later, using higher wind speeds and fluorescent dyed paraffin sprayed on the model, they tracked the path of the wind at ground level. When the paraffin dried out streaks of dye showed particularly turbulent areas east and west of Deanhead. The remedy was to open out the whole cutting, providing stepped banks 15ft wide on which snow could accumulate. Slicing the ends of the cutting, one opening onto exposed moorland and the other onto the 240ft Scammonden Dam, removed the danger of high-speed side winds to tall vehicles emerging from the cutting. In another wind tunnel, at Nottingham University, the possibility of designing wind deflecting fences
(Caption page 62) Opposite: in the Deanhead Cutting (top) looking east towards Huddersfield and (bottom) structural detail of Scammonden Bridge. The thin bridge supports have a small aerodynamic section. Below: from Scammonden Bridge M62 climbs across Moss Moor to the BBC masts on Windy Hill. The 3/4 mile length of split carriageway surrounds a farm and several acres of rough pasture. Farming continues undisturbed behind a landscaping screen of conifers.
was investigated. In the event, a promising one made from terylene strips was not adopted.
During the summer of 1962 two trial embankments were erected on sites along the line of the motorway. Capped with a thin tarmac layer and with sides of varying slope they proved that a side slope of about 1 in 5 discouraged the wind turbulence that led to drifting and even aided the dispersal of settled snow. In areas of low land values the cost of the extra land required to build these broad slopes was insignificant compared with the value of maintaining snow-free carriageways.
At no point is the line of the road far from heavy industry - which, in both Yorkshire and Lancashire churns out immeasurable levels of pollution. This dirt is precipitated from rain over the Pennines, contributing massive doses of acid to the already corrosive soil and peat. This contamination makes short work of concrete and steel alike and demands special measures to ensure the permanence of fences, culverts, bridges and drains. For the culverts, asbestos bonded steel pipes were chosen and drains and water courses were finished with high-density hydraulically pressed paving to limit the ingress of water.
With two reservoirs in the area, the new one created by the Scammonden Dam and a second lying between the M62 and the A672 just west of Deanhead cutting, separation of motorway drainage water contaminated by salt in winter and oil products throughout the year, from the adjacent streams was essential. This was complicated by the need to ensure continuance of supply to the remaining woollen mills farther down the valley. One of the initial site operations was to construct 3.5 miles of paved ditches and 2 miles of Armco steel culvert to protect the 1500 acres of water catchment area traversed by the motorway.
It is motorway building policy and commonsense economy to use materials excavated from cuttings in the building of adjacent embankments. This means using a system of excavation that yields material of the right grade for compaction. Yorkshire engineers carried out full-scale trials into various methods, including ripping - which was discounted because it produced excessively large slabs of rock, and multi-row delay blasting which was eventually used. Even the massive cuts at Deanhead and farther east at Pole Moor could not provide enough rock for crossing the moor to Windy Hill on the Lancashire side of the boundary. So, distasteful though it may seem to the true Yorkshireman, 200,000 cubic yards of Lancashire from the Windy Hill cutting was brought east to Moss Moor by the contractors Sir Alfred McAlpine and Son Ltd. Because Yorkshire excavated this short section across the boundary they also had the job of designing and building the 220ft Pennine Way bridge which spans the road some 200 yards into Lancashire. Rumour has it that the bridge, complete and dangling over a lunar landscape of spoil tips and contractors' equipment at the moment, was a personal whim of
(Caption page 64) The specially designed M62 fence, by Darlington Fencing Co, stops the most mercurial sheep and offers minimal snow and wind resistance. Below: Extensive dram culvert and stream diversions (left) border the carriageways. Safety fencing (right) is of the tensioned wire rope type (British Ropes Ltd) mounted on steel posts with reflector caps
Ernest Marples, the then Minister of Transport and, it is said, a keen hiker. After all, the interchange of M62 and A672 is not many yards away and little ingenuity would be required to provide a footway under one of its bridges.
West Riding design their own bridges and for the Lofthouse (M1) - Gildersome section carried through a scheme evolved for their part of M1. This shows in the dated structures at the Lofthouse interchange but does not apply to the special cases of the Pennine Way Bridge, a three-pin arch with side cantilevers supporting pre-stressed concrete approach spans, and the Scammonden Bridge, carrying A6025 over the Deanhead cutting. Both have parapets which follow the line of the original mountainside. Scammonden Bridge has a span of 410ft and was designed to minimise wind disturbance in the cutting - a fixed spandrel arch supporting a 658ft long deck with mass concrete springings was found to be the most practical structure. It required 70 miles of scaffolding during its construction - the scaffolding carried 1100 tons of ice in winter 1967 and because of its harp-like configuration gave rise to a low moaning sound in the wind attracting tourists from miles around.
To the contractors, the £11millions section meant solving problems that had never been faced before in Britain's motorway programme and fulfilling the prediction of Colonel Maynard Lovell, the then West Riding county surveyor, of being "a most fascinating challenge''. It meant working men in weather that brought icicles to their beards and the threat of death by exposure if lost in the thick fogs that endanger work throughout the year. Driving heavy construction vehicles on steep gradients and boggy ground where the average rainfall is between 50-60in per year, McAlpine's completed on time in December 1970 after four years, during which they moved over 12 million cubic yards of material and employed over £3 millions worth of plant at peak operation.
The M62 Pennine section is not only the culmination of many years' testing and experimenting, surveying and engineering, but also opens an important trade route without creating a scar on the landscape, for much of this moor and hill scenery could not be enjoyed without the motorway. From nearby vantage points, like A672, nothing but an inch or two of lorry roofs can be seen of its progress. In the longterm the provision of tree snow barriers and specially blended grass areas can do nothing but good on the bleak moor.
The Pennine section apart, M62 has not been designed without a measure of the ruthlessness that has preceded the progress of other modern roads. At Outlane the villager's protection society claims some success in getting the A640 interchange moved eastward out of the village, although a more western route at the bottom of the Black Brook valley, avoiding the houses entirely, would have been preferred. Their remaining fear is one of isolation from Huddersfield town centre - the real possibility that they may become a forgotten part of Yorkshire. Worsley, on the north-west outskirts of Manchester, has become the scene of a junction of the M61, M62, M63 and, shortly, the M64 spur into the city centre. Previously regarded as an oasis in an area of indifferent scenery with views across the Mersey flood plain and woods of fine mature trees, it is now the site of Britain's largest interchange - locally known as ''spaghetti".
(Caption page 65) Just across the county boundary is the Pennine Way footbridge over the Windy Hill cutting. The bridge designed by West Riding County Council, was built in advance as Yorkshire needed the cutting material to build the embankment across Moss Moor.