MT 120/314

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Trunk road preparation pool schemes: proposed link between Ringway 3 at South Mimms and the North Orbital Road; feasibility study; correspondence with Eastern Road Construction Unit; press notice

Date range1973-1974
LocationNational Archives (see all files stored here)
CatalogueSee entry
File baseSeries MT, subseries MT 120

Files MT 120/315, MT 120/316/1, MT 120/316/2 and MT 120/316/3 all redirect to this page as they are effectively a single item split into five physical parts.


These files form a five-part series that covers the creation of the section of road that is now the M25 between junctions 19 and 23. The volume of material that was generated spans five individual files, which run in chronological order.

The overall picture is that, in early 1973, the existing plan was for the Department of the Environment to build two rings around London - one was Ringway 3, for which a scheme was under construction between South Mimms and Potter's Bar. The other was the North Orbital and South Orbital Roads, for which another scheme was under construction between Maple Cross and Hunton Bridge. The publication of the Layfield Report, which was the conclusion of the massive public inquiry into the Greater London Development Plan, recommended that the sections of these roads that were furthest advanced (being the south and west sides of the Orbitals and the north and east sides of Ringway 3) should be connected to form a single circuit, and that the other parts should be abandoned.

The DOE's acceptance of the Layfield Report's conclusions marked a sudden about-turn in policy for the trunk road system north east of London, and these files deal with the unexpected need for a new road between Hunton Bridge and South Mimms, which would be the only part of the new single orbital road that would have to be created from scratch.

The individual files break down the story as follows.

MT 120/314

This file covers the period 1973-74, which is the "what now?" period. There is much correspondence on the subject of the Layfield Report and its consequences, and how existing road schemes should be handled. It appears, for example, that Ringway 3 between M1 and A1 was already in the trunk road preparation pool at this point as an "accelerated scheme" and it was no small task to put the brakes on it.

The outcome was the setting up of a feasibility study into the new section of road that was required, and there are many draft versions of its terms of reference here, as well as lots of impenetrable talk about computer modelling techniques that could be employed. Finally, there are some plans at various scales of the possible routes that would be considered.

MT 120/315

Entirely taking place in 1974, the events in this file are minutes of meetings held by the people conducting the feasibility study (some from the DOE and others from firms of consulting engineers), and a great deal of excitement over the fact that the DOE's guidance on the capacity of different road cross-sections was about to change - it was decided that this scheme would be one of the first to use the new, revised figures (meaning, for example, that where the old guidelines would demand a three-lane motorway over a certain threshold, the new guidelines would only require a road of that type at a much higher threshold).

It was also one of the first schemes to benefit from a Ministerial decision that public involvement in road scheme planning would be greater, and that consultation would take place earlier in the process. As a result there is much work here in setting up a consultation exercise into the routes that were being considered, which was viewed as something of a novelty.

MT 120/316/1

This file spans 1974 to 1976, in which the results from the consultation exercise were analysed and the feasibility study was moving towards the point at which it would publish a report. There are many very slightly different draft versions of the report, or parts of it, in this file.

There are other memos and correspondence here which shed some light on other interesting points, one of which is that the acceleration of this section of road through the planning process (something that was being done for a brand-new road, barely considered before, at astonishing speed for the time) happened at the expense of other nearby road schemes which the Eastern Road Construction Unit had to put on the back burner. The short of it is that it seems this section of road was responsible for the A41(M), which had almost been ready for construction, being delayed by two or three years - a drop down the priority list from which it never recovered.

MT 120/316/2

We are still in 1976 here, and my scrappy pencil notes say, in exasperated tones, that "EVEN HERE the feasibility study report is only a bloody draft".

This is still a very worthwhile part of the story, however, as it includes detailed plans and layouts for all the route options that were considered, including junctions.

MT 120/316/3

The final part of the file takes us through to 1977, where we find the full feasibility study report, plus another technical and economic report by the consulting engineers which is best described as being utterly impenetrable. If you enjoy network assignment diagrams that were used in conjunction with mid-1970s computer modelling of projected traffic flows, it's just the ticket.

There is a lot of duplication from the previous item here and little that is new, unless you've completely overlooked the many drafts in previous files.

People with camera copies

Chris Marshall has a partial copy.