The Fiction of the Traffic Census - According to the Highways Agency

In an earlier post, we explained how the Department for Transport has a methodology for working out what they call the annual average daily flow (AADF).  They seem to rely on a manual traffic census conducted every 2, 4, 6 or 8 years and supplement this with data from Automatic Traffic Counters.

You should read that original article, because it explains why, even if the methodology is used, it is inappropriate for a road like the A303. Anyway, onwards.

We thought it might be helpful, in understanding the traffic flows on the A303, to have an idea of how often manual censuses actually take place, as that says quite a lot about how up-to-date the data being used in the forthcoming reviews might be.  So, we fired off an FOIA to the Department for Transport and back came an answer from my new chums at the Highways Agency - charged with managing England's motorways and strategic A-roads on behalf of the DfT - or should that be mismanaging them?

We asked for the details of any traffic censuses on the stretch of the A303 through Winterbourne Stoke since January 2000; very unambiguous and straightforward.

 The reply we got, as with previous FOIA responses from the Highways Agency, took as by surprise.  It was the one answer we were definitely not anticipating: "We are unaware of any traffic censuses for the A303"

Wow, not just no traffic censuses on our little bit of the A303 since 2000, but none on any of its 90 mile length during that time period.  So, decisions on dualling (or not!) the A303, the closure of the A344, the drawing up of Somerset Council's study on the A303, A358 and A30 have all been based on figures that were not based on manual census data which lies at the heart of the DfT  Road Traffic Estimates Methodology.  At least that is what DfT claim to do - but seemingly not when it comes to the A303.

Frankly, I think that is pretty disgraceful.  I'm sure the HA will protest that they can get all the information they need from the automatic traffic counters (ATC's), but DfTmake it quite clear that the ACTs c.an only collect some of the data recorded in manual censuses that are used to classify vehicle types.  The types of traffic are important when considering the A303 and the ACTs.  When a manual count is carried out, 6 different classifications of HGV are recognised (3 rigid and 3 articulated).  ACTs only recognise HGVs as being rigid or articulated - so they couldn't tell, for instance, the difference between a rigid HGV with two axles and a rigid HGV with four axles.

Which, if DfT/HA are to be believed, makes me wonder how they have come up with traffic statistics like these (click to see enlarged view):

Clearly, these are the manual census categories - yet no manual censuses have been carried out according to HA.  Interpolation by witchcraft perhaps?  Once again, it seems that the Highways Agency:

A. Couldn't tell their arses from the their elbows - even with the benefit of a map.

B. Are inefficient, ineffectual and can't find their own data.

C. Are being disingenuous.

We have asked for clarification.

We also think the Department for Transport should do a bit of re-branding of the Highways Agency with respect to the A303 - we think this would be a tad more honest: