Road Numbers:
How it happened

Road numbers involve a world of zones, boundaries, rules, conventions and intricacies. Who was behind all that detail, and why did they think it was important?

Today we take road numbers for granted - they’re just there, and they have been there for a hundred years, which means that none of us have ever known a world without them. But it’s interesting to step back and ask just why roads were ever numbered. Why hubs and spokes? Why A and B? Who thought it all up? And how are numbers devised and applied today?

The story of classification in the UK is not quite as straightforward as it might be - disrupted by war, complicated by a French industrialist and sabotaged by cartographers. This is the story of how the Men from the Ministry came up with an awful lot of numbers.

A world without numbers 

Since humans first inhabited the British Isles there have been roads, but they all looked much the same and it was often difficult to tell them apart. That didn’t matter too much until the early twentieth century, when motor cars appeared and the demands being placed upon city streets and country lanes began to change enormously.

Local authorities found it difficult to keep track of maintenance work. Central government had no accurate measure of the distances between towns. Travellers lost their way because one road was much like another, and road signs were generally poor.

In 1910, with motor traffic rising, action was taken to sort out the mess. A government body called the Road Board was set up under William Rees Jeffreys. He was instructed to upgrade existing roads and build new ones using money from the new ringfenced road and petrol tax.

The trouble Jeffreys and his colleagues faced was in working out where to spend their enormous budget.

There was nothing to tell roads apart and no data to say which roads were busy. Information was needed and, in 1913, work to gather it began under Sir Henry Maybury, one of the Board's senior engineers. The task was to classify each road depending on its traffic level. Once classified, roads could also be assigned numbers for reference. A document from about 1914 explains:

This concept evolved, so that each road was split into numbered sections. A new section would begin at each road junction, and the location of maintenance work could then be identified as being at "5-315", that being section 315 of road 5.

A circular was sent to all County Councils in April 1914 asking them to commence traffic surveys so that classification on this basis could begin, and a sample scheme for Kent was drawn up.

The intention right at the beginning was for three categories - Class I and Class II, for the two busiest groups, and everything else being regarded as “unclassified”. But the nature of the numbers kept shifting, and after a while numbers would be specific within individual counties, so roads would gain a new number when they crossed county boundaries.

The outbreak of the Great War in 1914 brought all work to an abrupt stop. It was only in September 1919, as affairs were returning to normal, that Sir Henry was invited to resume his classification work, now under the Ministry of Transport.

Men of letters

Setting up the new Ministry took time. When enough staff became available for the project, Sir Henry and his colleague Colonel Richmond wrote again to County Councils asking them to perform traffic surveys on all their roads and return the data so that classification could begin. This work got under way in 1920. The system of Class I and Class II roads was retained, but there was now a new concern, which was that road numbers might be useful for navigation. With this in mind the idea of duplicating numbers in each county was scrapped.

It's hard to say how influential the Michelin company was in the numbering system that was eventually adopted, but it was certainly influential in most areas of motoring in the early twentieth century, and André Michelin himself (its founder) took a great and personal interest. He wrote four papers on the subject of French and British road numbering, specifically for the Ministry's attention, explaining the French system and proposing a system for Britain.

One document lists the London radials and numbers them from one to five - missing out the London-Dover route and giving England and Wales just five zones. It's not clear whether this is just a mistake in an early draft, as there are references on the same page to six zones.

A paper titled “Suggested System of Route Numbering”, written by Col. Richmond himself in May 1921 (referring only to England and Wales) lists to the A6 as running to Glasgow, and states that "number 6 sector is bounded on the North by the Carlisle - Berwick-on-Tweed Road to which No. 7 is allotted". Had the A7 run along the England-Scotland border it would have split the system into two very clear parts, with zone 6 prevented from entering Scotland at all.

The process of allocating numbers within zones was even more intriguing. There appears to have been a system of letter codes indicating first and second class status, probably used to distinguish one from another while decisions were taken about which routes would take precedence where roads of the same class met. Often Class I roads in a given area were given a single letter and Class II roads a pair of letters.

By August 1921, much of this initial work was nearing completion, and correspondence was being sent north for Scotland's highway engineers to begin considering their own scheme. There was still great uncertainty about what would happen north of, and even along, the border.

W.L. Campbell at the Roads Department in Edinburgh was instructed that "the routes you should number in Scotland are 7, 70, 71...79; 8, 80, 81...89, and 9, 90, 91, 92...99." The letter continued:

English numbering was now in progress, and Scottish numbers were about to be produced, but this was still a system in its infancy. It would not be long before engineers found that four-digit numbers were inevitable on both sides of the border and in every zone. But we came very close to having a bizarre "A7a", which would only exist to contrive a change of zone along the border.

The same letter went on to suggest that, north of the recommended route for A8, which was Leith to Gourock, there would probably be enough zone 8 numbers to dispense with zone 9 completely.

This was a serious proposal and diagrams were produced to demonstrate that it was viable. In this interesting scheme the rest of zone 8 was allocated as follows:

• A80 Edinburgh - Inverness via ferry across Forth estuary
• A81 Rosyth - Aberdeen via ferry across Tay and Dundee
• A82 Aberdeen - Inverness
• A83 Oban - Perth - Dundee
• A84 Glasgow - Perth - Stonehaven
• A85 Edinburgh - Stirling
• A86 Glasgow - Fort William - Inverness
• A87 Fort Augustus - Kyle of Lochalsh (for Skye)
• A88 Inverness - Thurso

It’s not clear why this considered. Possibly the engineers simply thought there was no need to use more numbers than necessary. It’s been suggested that, with Irish independence still a few months away and by no means certain, zone 9 was being reserved for Ireland. But that is highly unlikely because, even before independence, both Northern and Southern Ireland were operating as self-rule territories that would decide their own entirely separate numbers - which, of course, Northern Ireland eventually did.

Another possibility was that numbers beginning with 9 would be useful spares, with a stock of important-sounding two-digit numbers ready to be deployed anywhere in Great Britain when new roads opened.

All the same, documentary evidence is patchy, but in the end zone 9 was retained, and both Classification and the first round of numbering were finished by 1922. The first numbers, A1 to A99, were cleared to go on signs.

Going public

Map publishers had long known that road numbers were coming, and most of them were very eager to get hold of these exciting new codes that identified each link in the network. Bartholomew’s were so eager to get a head start on their competitors that they published a map with leaked information on the routes of A1 to A99. The company was left looking a little foolish when the final scheme was revealed with several noticeable differences the following year.

Michelin were keen too. When the first batch were released in July 1921 they were invited to send representatives to the Ministry to inspect the new scheme. In order that there would be no doubt whatsoever, no matter how minor the question, a series of obsessively large-scale maps were drawn up for the handful of places where the running of two route numbers concurrently could not be avoided.

There was also a great deal of interest from members of the public, and archive documents on the subject contain an incredible number of letters asking how road numbers were allocated or how the system worked. Each one got its own reply, individually written but always along the same lines.

T for trunk

A and B were settled, but before long the letter T was threatening to make a comeback. By the 1930s, long-distance motoring was becoming a reality and the Ministry of Transport was concerned that major long-distance routes were inconsistently maintained by County Councils. The Trunk Roads Act of 1936 would resolve this by giving the Ministry direct control of major roads.

The Act stipulated that the new Trunk Roads must be numbered for reference, and there was much head-scratching about what the numbers should be. In one draft plan, A-road numbers would be reorganised so each trunk route had the same A-number from start to finish. That idea would see the A62 and A63 replaced by a coast-to-coast A580 between Liverpool and Hull. This was abandoned in favour of new T-numbers, most of which would be produced by copying the number of the A-road that each Trunk Road used for the greatest length, such as the T30 from London to Penzance. However, a few wayward decisions were also taken - the T22 crossed northern England, bearing no relation to the A22.

It was discovered quite by accident. A senior cartographer at the Ordnance Survey was enlisted to write a leaflet explaining the new coordinate system, and sent his draft text to an old friend to get his comments on it. The old friend happened to be a senior Ministry of Transport civil servant working on Trunk Road numbering. He immediately realised that it would be possible to send work crews out with a map and a set of co-ordinates, which meant the Ministry could keep the whole messy business of Trunk Road numbers out of sight. T-numbers were created, but used in the end just for internal reference.

If it wasn't for a chance encounter between old friends, we might even today be driving on T-roads.

A century of change

In 1937 the T-road question was resolved by the Ministry’s dedicated Roads Classification Section, but road numbering would not stay novel or important enough to retain its own department for long. Over time it has been progressively demoted to a point where it sometimes feels like an afterthought.

The original 1920s system was, for a short while, maintained with extreme diligence. Through the rest of the twenties, annual revisions to road classifications were produced, with numbers being changed wherever traffic levels called for an amendment to a road’s class. A major revision was carried out in 1935, with several main roads being diverted in an attempt to improve long-distance navigation. But that was the last time road numbers would receive a complete review.

The strictest rules of the original system were progressively abandoned. New roads no longer had to receive the next number within their zone in strict sequence, and existing roads began to be diverted on to bypasses rather than staying doggedly on their original line. Concurrencies - what road enthusiasts often call multiplexes - where one road number is “carried” along another, reappearing later, began to be permitted. Pragmatism replaced purity.

There is some evidence that the Ministry’s own management of classification deteriorated over the decades. By the late twentieth century its card index of all road numbers was no longer accurate or useful, with many new numbers missing, old numbers out of date and itineraries incomplete. It is fair to say, at this stage, that SABRE holds a far more complete and accurate record of the UK’s road numbers than the modern Department for Transport or any other highway authority.

Then, the greatest change since 1935 happened in April 2012, when the Department for Transport handed responsibility for classification over to local authorities. Road numbering is now decentralised and devolved. No approval is needed if your local council wishes to make a new A-road or delete an existing B-road. They may do as they please.

On the face of it this sounds like a recipe for chaos, but the official guidance does place a responsibility on authorities to consult with each other when they want to make changes to a road that crosses a boundary. The DfT also states, as part of this policy, that it will maintain a central register of all road numbers (good luck!) and should be contacted to obtain an unused number when a new one is needed. However, they also admit that “the department recognises that neither local authorities nor central government will have comprehensive records of classification decisions taken before 2012”.

It remains to be seen whether the walls will come down on the road numbering system in light of this development, or whether the nine zones and other associated rules will survive in some form.

Most likely we will keep muddling through with a mix of good and bad decisions and a system of numbers that only grows more complex with time. When you’ve been numbering roads for a hundred years, it could hardly be any other way.