This page was updated in January 2021
What is really meant by “Expressway”?
In its design, an Expressway sits somewhere between an A-road and a motorway, but it is clearly nearer the latter. The proposed expressway will be a minimum dual carriageway road, potentially more.
But how about its function? Will it be more like a motorway, or more like an A-road?
Expressways are supposed to allow mile-a-minute speeds and differ from motorways only in the volume of traffic they are expected to handle (less than a motorway’s).
Motorways are obviously designed for rapid, long-distance movement across the motorway network. They are not designed to handle local, commuting traffic (most motorway junctions are set a minimum and long distance apart, partly to prevent this happening) and, when they do, they tend to become congested just like A-roads. The M-25 is an example of this.
An expressway has more junctions than a motorway because it is designed to service houses that are specifically associated with it (as in the Ox-Cam scheme). Thus Highways England imagines an expressway will deliver mile-a-minute speeds but to essentially local traffic, most of which is probably commuting.
The diagram below, from here, shows what Highways England hopes will happen with the Expressway.
The three circles are centred on the three major cities on the Ox-Cam route, Oxford, Milton Keynes and Cambridge and show the 45 minutes journey to work catchment areas in the absence of the expressway (at the top) and with the expressway (below). At present (i.e. the upper three circles, above) the circles do not overlap; each employment centre is relatively unconnected to the others. The expressway brings about an overlap in the catchment areas for the same 45 minute drive time to work. This is presented as an advantage of an expressway but it implies a longer commute to work for a more widely dispersed work-force.
It appears, however, that even Highways England’s own engineers do not yet know if the expressways will in fact deliver these faster, longer-distance journeys to work. Expressways are neither motorways nor A-roads, but the housing associated with the Ox-Cam expressway will make it more like an A-road than a motorway. Expect average car speeds to be lower, and therefore journey times to be longer, and the 45-minute journey time catchment areas to be smaller than those currently predicted by Highways England.
The hoped-for high speeds of expressway traffic is the major attraction of the expressway project, and are again emphasised in the wheel graphic below that appears both in the CAR and now on Highways England’s expressway website.
The two circles at the top of the graphic give the numbers of people that are within a 45 minute drive time either of the Oxford Science Park or of Milton Keynes. These numbers are very large because of the expected large catchment areas shown in the previous graphic.
Unfortunately for Highways England, the journey times used to create both graphics in this section were derived from the South East Regional Transport Model (SERTM) using as input only the existing number of cars plus an additional number due to Local Plans (the geographical location of which is already known). The model did not include all the additional expressway cars arising from at least 550,000 expressway-unlocked houses (to say nothing of the ‘London commuter’ houses). Thus that imagined 45-minute journey time will in fact be very much longer if cars really do try to reach those destinations from far-flung expressway homes: far-flung homes located with the expectation of those modelled drive times.
This graphic is a good example of how Highways England is approaching the transport problems of the Arc. Delivering more people over longer distances but in the same drive-time as at present is a recipe for more commuting, not less.
Notice something else?
The wheel graphic contains pictures only of cars and vans.
There is not a single bicycle, bus or train shown in it.
Yet aren’t we supposed to be using pedal power and public transport more in the future than at present? Not according to Highways England, it seems.
That figure of 470,000 people being within a 45 minute drive time of the Oxford Science Park (wheel graphic, top left) would overwhelm the park if even a fraction of them decided to visit it on any one day. The Oxford Science Park covers an area of 75 acres and is home to 90 companies employing 2,500 people. Why is it at all of interest or relevance that almost half a million people (188 per Science Park employee!) should want or need to be within a 45 minute drive time of the Park? If they all chose to visit the Park on the same day, each in their own car, the Park would be entirely covered in parked cars (all 75 acres of it) eighteen cars deep. Yes, we too can do stupid modelling of expressway situations.
Most of the claimed financial benefits of the expressway arise from reduced journey times, which are monetised in the Benefit:Cost calculations of the expressway (link to). These benefits may well turn out to be illusory. Should you wish to take a speedy car journey along the expressway from Oxford to Cambridge in the future, you will have to negotiate the local traffic from at least 360,000 new houses (the total across all junctions), circulating between about a dozen junctions along the way.
It didn’t work on the M25 and it won’t work on the Ox-Cam expressway.
If the expressway won’t work, what is the alternative? Click here to find out!