Three steps to metric height signage

In the DfT’s recently announced review of UK signage, it was revealed that there will be a new dual-unit height warning sign prescribed to allow authorities to sign in dual units without needing two signs. However, notable in its absence is a requirement for authorities to use this sign and cease installing imperial-only signs, which means the problem of foreign lorry bridge strikes has no end in sight.

The solution to this whole problem appears as simple as mandating dual-unit signage and removing imperial-only versions from the regulations. However, as per my recent post on the SABRE forums, my view is that dual units on single signs, while better than imperial-only, isn’t the best long-term solution because it requires drivers to read twice as much information compressed together in smaller text, making the sign less clear and therefore less effective as a warning in those split seconds available to drivers to process it. Having dual units split across two signs is just as bad, as it presents the same problem of excessive information but with the additional costs of having to manufacture and fit twice as many signs and the increased visual clutter that ensues.

As far as I can see, the only reason imperial indications on height signage are necessary at all appears to be that that Regulation 10(2) of the Road Vehicles (Construction and Use) Regulations 1986 still only requires vehicles over 3.66 metres tall to display in-cab notices in feet and inches. Because there is no requirement to show a metric figure, the vast majority of commercially available reconfigurable in-cab indicators don’t show it, so to have metric-only height signs on the roads would be a safety risk.

All it would take to solve this problem would be to make three simple regulatory changes:

1) Amend RVCUR to require both imperial AND metric height indications on in-cab notices;
2) Amend TSRGD to replace all imperial-only and dual-unit height-related signs prescribed in diagrams 530, 531.1, 532.2, 532.3, 780A, 780.1A, 780.2A, 818.3, 2002, 2003, 2027, 2107, 7284 and 7284.1 (plus one or two others I might have missed) with metric-only versions; and
3) Amend TSRGD to define a transition period during which all existing imperial-only height road signs would continue to be legal (existing dual-unit signs could be kept legal indefinitely).

As soon as these regulatory changes came into effect, all high vehicles on the roads – both domestic and continental – would have their height displayed in-cab in metric, and imperial-only height signs on the roads would begin to be automatically phased out during the transition period at minimal additional cost to local authorities during the normal course of sign replacements, just as in the case of pre-1981 weight limit signs in “tons” and “cwt”.

After the transition period is over, all height signs will be new metric ones or older dual-unit ones, so in-cab indicator requirements can be relaxed to only require metric. Job done.

The DfT couldn’t object to this on grounds of cost. The only taxpayer expense would be the administrative costs of notifying all registered operators of oversize vehicles of the date of the change (the costs of changing in-cab notices would be borne by the operators themselves) and updating official documentation.

Of course, if you’re going to remove imperial height-related signage from TSRGD, you might as well be consistent and remove imperial width/length-related signage as well. There seems to be no practical reason at all why these should remain in imperial, since vehicle manufacturers’ specifications and even the construction regulations themselves have long been in metric.

Surely Network Rail and and the Police, among others, would be happy to put pressure on the DfT to carry out these simple, cost-effective improvements that would pave the way to ending the problem of bridge strikes due to unit confusion once and for all?