The Department for Transport is investigating proposals to introduce consistent bridge marking standards in both metric and imperial units.

The signage would show both imperial and metric height, width and length limits.

The DfT has carried out its most comprehensive review of traffic signs since they were introduced in 1964 and is consulting on planned changes.  It says a lack of understanding of imperial measurements has been implicated in incidents of bridges struck by over height vehicles. 

While highways and bridge authorities have had the opportunity to mark bridges with imperial and metric measurements in the past, this has been done by the installation of a separate sign.  The proposed change gives the power to mark both measurements on one sign.

Younger and foreign drivers in particular are presented with a challenge when they are more accustomed to metric measurements rather than imperial as they have to make the conversion, often with little time.

Vehicles with an overall travelling height over three metres must have a notice in the cab which indicates the height in feet and inches or in imperial and metric.

With more than 1600 bridge strikes in 2014/15 throughout the UK, the Freight Transport Association has welcomed the proposals, and says it is vital that signage can be easily understood by drivers who have to negotiate low bridges and narrow spaces.

The FTA has made a submission in support of the change.

Malcolm Bingham, FTA’s head of road network policy, said: “While the new rules have still to be finalised, it is proposed that highway authorities will be allowed to replace the current signs as they become life expired.  FTA has urged the DfT to encourage early take-up of the new option.”