Star.pngStar.pngStar grey.pngStar grey.pngStar grey.png

Road Widths

From Roader's Digest: The SABRE Wiki
Jump to navigation Jump to search
Road Widths
Cameraicon.png Pictures related to Road Widths
No pictures uploaded (Upload?)
Quick Links
Single carriageway • Dual carriageway

Even in the modern age, the width of a road is by no means standard. Today's roads vary from the wing-mirror brushing country lanes to vast 8- or 10-lane motorways, plus hard shoulders and central reservations. This page is by no means a technical look at the width of roads, rather a general overview of how so many different widths have originated.


Perhaps surprisingly, the concept of a road in the modern sense, as opposed to a path or 'way', does predate the Roman invasion. However, such roads were by no means widespread and were only really found in those areas with regular contact with the Romanised world. Little is known of the construction or width of these roads.

The Romans were the first to build a proper network of roads across the British Isles. These roads ranged from the famous Watling Street, Fosse Way and so on to small local roads and drives. As such, widths varied considerably. The width of the paved road seems to have averaged 7 m for main routes, although some excavated sections of Watling Street have proved to be over 10 m wide, whilst The Fosse Way is less than 6 m in places.

Minor side roads, then as now, are unlikely to have been any more than the width of a cart, so 2 m at best, and there were doubtless a number of important cross-country routes which survived as rough paths, or tracks. The volume and type of traffic on the route, even 2000 years ago, was critical to the width of the road constructed.

Middle Ages

The next formal period of road construction came in the early middle ages. Prior to that, many thousands of miles of roads and paths had been created, but few were built with any grand plan in mind, rather they just became the route taken between two places. Most of the English Midlands had developed the open field system of Agriculture, which often meant that there were inumerable small paths across and between the fields. However, the less populated northern and western parts of the country were enclosed piecemeal, in small fields taken, perhaps, one by one from the woodlands and moorland that surrounded them. Here, the narrow country lanes we still see today, winding madly between high banked fields could be well over a 1000 years old. It was rare for new roads to be put in, except as and when the enclosure of land reached pre-existing routeways through the woodlands or across the heath, and in these cases land was at such a premium that the roads were kept narrow, little more than the width of a cart, just as we see them today.


When those parts of England which had kept the open field system were finally enclosed, starting in Tudor times, and ending in the early years of the 20th Century, the enclosure plans were drawn up almost with complete disregard for pre-existing land holdings. This led to new roads being put in where they were needed, often running in long straights and then kinks between fields. These roads were laid out with widths dependent on the volume of traffic, but never less than about 18 feet wide. The most important routes could be anything up to 60 feet (18 m) wide, enough for a full, wide, modern dual carriageway! These great widths can still be seen, even though the modern surfaced roads may only be 5 or 6 m wide, they lie between wide grass verges, showing the original width of the road. Of course, these great widths were required in pre-tarmac times in order to mitigate against the worst of the winter weather when roads often became choked with mud and sludge, making it difficult for even the hardiest horses to proceed.

On the Somerset Levels, these wide roads survived to the Turnpike era, with the Bristol to Bridgwater road, now the A38, at Weare claimed to reach a width of half a mile in places as it struggled across the waterlogged fields on the banks of the Rivers Axe and Yeo. On higher ground, where the ground was stonier or better drained, such widths were rarely needed, but still sometimes laid out by the enclosure acts.

Scottish Highlands

In c1725 General Wade started building his military roads in the Scottish Highlands. These were initially built to a standard width of 18 feet, narrowing to a minimum of 15 feet for bridges and in cases of difficult terrain. 25 years later when Caulfeild took over after the 1746 Jacobite Rebellion, he started off with the same standards, although most of his surviving bridges from the early years seem to also be 18 feet wide. However, as the years went by, the roads got narrower. By the later 1760s, they seem to have been built to a maximum width of 15 feet, often narrowing to 12 feet. This was doubtless to save money and time at a time when the need for the roads was being questioned by government.

Then, in 1802, Highland Roads were once more back in the limelight, with Thomas Telford given a commission to build Telford's Highland Roads roads and bridges across the Highlands. He reverted to the 18 foot width as a minimum, with some roads built wider again. However, as many of his roads are still in regular use it is difficult to tell exactly how wide they were originally, as they have experienced 200 years of improvements.

Modern standards

By the dawn of the motoring age, there were a great variety of road widths across the British Isles. However, with the advent of modern tarred roads, the need to have the super wide rutted routes of the past had gone. In a relatively short space of time, road widths had come to be standardised back at the 5-7 m widths of the Roman era, This allowed room for tow carts or carriages to pass, and space for pedestrians or horses too. In the early years of the car, there was no conception of the future needs that personal transport for the masses might bring.

However, by the late 1920s the rapid rise of car ownership, and the steady shift of haulage from rail and canal to road led to the construction of much wider roads. The first of these were the new boulevards leading out of cities, such as the Great Western Road in Glasgow, and a few years later the wide East Lancs Road between Liverpool and Manchester. Whilst the A82 was built as a full dual carriageway, wide enough in places for three lanes of traffic in each direction, the A580 was built as a 3-lane (S3) road, with a 'suicide lane' down the middle. However, both, and indeed many others like them, show a new understanding of what traffic requirements of the future meant to road building.

Elsewhere, the rough old windy roads that had served the country so well were being replaced at a rapid rate. From the A38 across the Somerset Levels which was widened to a similar S3 standard, at around 10 m or the A82 across Rannoch Moor in Scotland built to a width of around 6.5-7 m, these roads replaced older lines that had been as little as half the width of the new road.

The standards on road widths have increased further, and whilst many of the old S3 roads have been reduced to normal single carriageways, so disguising the old standards, the roads built today are wider than ever. Modern standards require a minimum of about 4.5 m width for a road to be considered as two-way, rather than single track. Even then, though, it may not have a centre line. Indeed, the many 6-7 m wide routes built in the 1930s are now considered narrow, with a minimum of 7.5 m required for two carriageways on through routes. Even 7.5 m is less than the width of main roads often built in the last 30 or so years, which are 7.5 m between the verge lines, with a further half metre beyond, and then gravel strips before grass is reached. These give the appearance of mini hard shoulders, although there are a range of factors behind their introduction.

Motorway travellers will be familiar with the 'narrow lanes' signs through roadwork zones, and these can be quite intimidating at times. They can be as narrow as about 2.2 m, but most motorways have lanes at 2.8-3 m in width, with the outside lane perhaps 2.6 m wide. Add in the Hard Shoulders and central reservations, and the full width of 3-lane (D3M) motorway is over 22 m, considerably more than the old 60 foot roads of the enclosure era, but then again they do have to carry a lot more traffic!

Urban roads

Roads in urban areas are ever more constrained in width than those in rural areas generally are. This is never so true as some of those micro-urban areas, villages, where old buildings and sharp bends haven't been swept away in the years before conservation and tourism took hold. This, of course, has been one of the drivers behind the bypasses built far and wide across the country. However, prior to the Victorian era, most urban roads were like this. Narrow, winding lanes, often with overhanging buildings, but as most traffic was pedestrian, with some horses and carts too, there was no need for wide roads in places where land was often at a premium.

By the Victorian era, however, the Industrial Revolution was in full swing, and the great cities of the the Midlands and North were being planned out along wide streets and large squares. In some cases, road widths seem to have been decided on a 'keeping up with the Joneses' principle, rather than anything scientific. Whilst London and the older provincial cities were more constrained by ancient land ownership patterns, new wide roads were put in as the cities expanded, and indeed within the existing Urban areas whenever possible. The bombing raids of the Second World War then allowed the planners to rebuild many of the other narrow streets to modern standards.

Road Widths
Road Basics
Physical layoutSingle track • Single carriageway • Dual carriageway • High Quality Dual Carriageway • Road Widths • Urban Streets • Abandoned Road
Legal typesAll-purpose Road • Special Road • Motorway • Trunk road • Principal road • Classified Numbered road • Classified Unnumbered Road • Unclassified road • Primary Route • Non Primary Route • Right of Way • Unadopted road
Road numbers1922 Road Lists • Classification • Defunct road • Euroroutes • MoT Maps • National Cycle Network • Numbering principles • Numbering anomalies • Disputed Numbers • Recycled number • Unallocated numbers • Fictional Road Numbers • Junction numbers • Essential Traffic Routes • Street Names
Road FeaturesArterial Road • Automatic Bollard • Balancing Pond • Belisha Beacon • Bott's Dots • Bypass • Cannon • Cats' Eyes • Cattle Grid • CD Lanes • Central Reservation • Chopsticks • Crash Barrier • Cuttings and Embankments • Cycle Lane • Emergency Phone • Escape lane • Expressway • Fingerpost • Flare • Ford • Gore • Green Bridge • Green Wave • Hairpin bend • Hard shoulder • Island • Junction • Layby • Level Crossing • Local Access Road • Managed Motorways • Milestone • Multi Lane Drop • Multiplex • No-Car Lane • Nose • Oxbow Road • Parapet • Petrol station • Play Street • Raised Pavement Markers • Ramp Metering • Retaining Wall • Road Studs • Roadside Art • Roadside Quarry • Roadworks • Secret motorway • Service Area • Signage • Smart Motorway • Snow pole • Speed Limit • Spur • Street Lighting • Surface Dressing • Temporary terminus • Throughpass • Tidal Flow • Tiger tail • Toll booth • Traffic cone • Traffic Signals • Tunnel • Vehicle Recovery • Walking and Cycling Friendly Road • Weaving • Wig-Wag Signals • Winter Maintenance • Zip merge
Traffic CalmingBuild-Outs • Chicane • Dragon's Teeth • Home Zone • Low Traffic Neighbourhood • Pinch Point • Quiet Lane • Rumble strips • Safety Cameras • Sleeping Policeman • Speed bump
Public Transport FeaturesBus Lane • Bus stop • Guided Busway • Park and Ride • Tramway • Trolleybus System
Other termsAnderson report • Guildford Rules • Highway Authority • Highway Code • Model Traffic Area • Motorway alphabet • Pre-Worboys • Primary Destinations • Roads by 10 • Transport alphabet • Worboys report

SABRE - The Society for All British and Irish Road Enthusiasts
Discuss - Digest - Discover - Help