Sunday, 3 March 2019

Dual Carriageway Terror

While I was out and about in the week, I happened to be cycling along a dual carriageway (on the path because I didn't want to become innovative jam) when I spied a gap in the central reservation barriers.

The road in question has the national speed limit and it is was patently obvious that many drivers were travelling at high speed. At least from where I was standing, sight lines across to the central reservation were poor and I did wonder if anyone ever crossed there.

The road's origins go back to the late 1920s and in fact the side road you can just see in the distance was cut in two by the road when it was built, so disrupting the network of very narrow country lanes which served the farms on the area. I have had a quick look at historic maps for the area and in the mid-1940s, the dual carriageway still formed a crossroads with the two side roads.

At some point, it was realised that having people turning right onto and from a trunk road was a bad idea and the traffic closed, but in common with countless places, we can still see a remnant of pedestrian access rights where old desire lines are kept with gaps in the barriers.

The layout of the barriers (properly known as 'safety fence' or a 'vehicle restraint system') is such that the pedestrian route means that one walks with their back to traffic in the central reservation because of the barrier overlap. If this was reversed, then it would be possible for a vehicle hitting the barriers to go through the middle.

In CIHT's 'Designing for Walking', Table 3 gives a ready reckoner on the suitability of different types of pedestrian crossing (there are clearly more detailed variables at any given site). I reproduce the first type of crossing above as it has a bearing on this case - I think you'll agree that a pair of dropped kerbs to cross a 70mph road (even in two halves) is a big ask for most people to use as a crossing. There is a DfT traffic count point nearby and the road carries some 36,000 vehicles per day - actually quieter than we might expect for a dual carriageway, but clearly still a large volume.

Looking at the foot of Table 3;

As well as being able to see what the colours mean, we learn that in this type of situation, the only appropriate choice is a bridge or an underpass. 

There is no history of pedestrian casualties at the crossing point and so unless there is ever a proactive programme of reconnecting pedestrian routes, it's unlikely this location will ever be looked at and so it will remain a quirk of history from a time where there were few cars and people would have walked between home and the farm they worked at.

So what? Well, we are still making the same mistakes as we did 90 years ago. Forever pushing for more road space, we still sever walking routes in the name of progress and once severed, they are never going to be retrofitted. For a large road building project, the costs to maintain pedestrian routes aren't costly and the engineering isn't difficult. Still, we seem to be very poor at learning from history don't we?


  1. The A414 both sides of Hatfield (Herts) has crossings like this. To the west there is even an equestrian crossing to link to a bridleway. Would any horse rider cross a 70mph "motorway"?

    To the east we have a crossing which would open up cycling and walking routes to Essendon, but of course no one would risk their lives doing so.

    So the A414 is really a minefield keeping people kettled, unless of course they have a car.

    1. These are everywhere - I guess the A414 is a little more modern which makes it all the worse.

  2. So many of these fast dual carriageways are built by easing the original alignment with cut & fill, creating cuttings that could have been bridged, and embankments which will still require culverts

    Leicestershire did this with Anstey Lane (sic) now a 50mph dual carriageway with a culvert essential to keep the local watercourse flowing underneath and not turning the road into a dam.

    My kids were cycling independently aged 10 to their junior school. But this one failure by LCC meant that the school/council had to find the school buses required.

    At weekends, with me riding shotgun, we tackled the viciously high speed geometry of the interchange roundabout on the A46 delivered thanks to the massive lack of forethought from LCC.

    By contrast in the Highlands such 'culverts' are built in 4 metre diameter Armco and carry the stream and a concrete path through side by side. A problem that would never have arisen, had the need to deliver a safe crossing been recognised from the outset.

    1. I've had a look at the junction and Anstey Lane - 'nice' ped crossing of the road up a bit from the junction. We have built so much token nonsense like this.

  3. just look at what they doing on the hs2 project - basically exact repeat