The Department for Transport (DfT) has announced its intention to finally end the use of imperial-only width and height restriction signs on Britain’s roads.
The long-overdue official acknowledgement that road safety can be improved by using metric measurements on vehicle restriction signs, comes as one of the proposed changes to the Traffic Signs Regulations and General Directions (TSRGD) 2002. The DfT has calculated that savings can be made from the projected reduction in costly accidents, such as bridge strikes, that currently involve a disproportionate number of foreign drivers, who generally do not understand restriction signs in feet and inches. The change will of course benefit British drivers too, as there will no longer be a need to know vehicle dimensions in two incompatible measurement systems.
“We are making changes to require both metric and imperial triangular warning signs to be displayed to give warnings of restricted headroom, with the upgrade being complete in four years’ time. Using the imperial sign on its own will no longer be permitted.
We are making similar changes to require both metric and imperial measurements to be displayed on all width and height restriction roundel signs, with the upgrade being complete in four years’ time. The current imperial-only signs shown in diagrams 629 and 629.2 will be withdrawn.”
“… approximately 10 – 12% of bridge strikes involved foreign lorries. This is disproportionately high in terms of the number of foreign lorries on the road network.
… Furthermore, for several years this Department has recommended, through the Traffic Signs Manual, the use of the dual unit height limit warning and regulatory signing in preference to the imperial only alternative.”
This is a welcome development. However, by replacing imperial signs with dual unit signs, an opportunity is being missed to make further savings, as in the not-too-distant future, the new dual unit signs themselves will be replaced with Vienna Convention-compliant metric-only signs. Garage forecourts, warehouses, and many car parks have already been using metric-only height restrictions for many years.
The proposed amendments to the TSRGD have come about as part of the Traffic Signs Policy Review, which was announced in September 2008. UKMA’s contribution to the review included the production of a leaflet, Traffic Signs 2.0, which highlights the many issues within the remit of the review that can be solved by switching to metric road signs. Unfortunately, the DfT continues to refuse to consider switching to metric measurements on road signs, and as a consequence it has dismissed the proposals in the leaflet, apparently even the recommendations that are not directly related to metrication, such as the use of language-independent up-arrows to indicate hazard extent, and the replacement, where possible, of text-only signs with standard pictograms.
As an example, the DfT has overlooked the principles of the 1968 Vienna Convention on Road Signs and Signals in the proposed new warning sign (diagram 7014.1) that indicates a temporary or permanent reduction to bridge headroom. The sign is text only, and consequently a non-English speaker might be unaware that the figures in brackets relate to a height restriction.
The diagram below illustrates how the essential information in the sign can be shown in a language-independent way using standard symbols from the Vienna Convention.
The Vienna Convention does not prescribe feet and inches on restriction signs though, and stipulates that the measurement units should be in metres only.
Traffic Signs Policy Review
Details of the Traffic Signs Policy Review can be found at the following link.
You can apply to join the Traffic Signs Policy Review sounding board, or comment directly using the following e-mail address email@example.com
You can comment on the new signs and other proposed amendments to traffic signs regulations in the DfT consultation, details of which can be found at the following link.