Every six hours, an HGV hits a bridge in Britain. That’s not including the vans, motorhomes and caravans whose hapless drivers misjudge – or forget – the height of bridges, tunnels and overpasses.
In 2022, Stonea Road railway bridge in Cambridgeshire was being hit roughly once every 11 days. It’s considered Britain’s most bashed bridge but a few in North Wales could give it a run for its money - see here for photos of 15 bridge strike howlers in the region.
Last week, pictures of another stuck vehicle in Flintshire was met with more sighs from locals who have seen it all before. A low bridge on Broughton Hall Road, close to Broughton Shopping Park, has been dubbed the bridge with “more hits than the Beatles”.
This time the unfortunate victim was a DPD delivery driver whose van was just a few inches too tall for the low-slung bridge. He came in for some gentle social media ribbing from the can’t-park-there brigade - but others had more sympathy. Among them was a former financial advisor who noticed apparent discrepancies in the bridge’s warning signage. Eddy Thomas, 73, ended his career by running a small B&B in Criccieth, Gwynedd, before retiring to Colwyn Bay, Conwy,
He now sees himself as something of a “trouble shooter”, delving into banking errors, website bugs and smart meter inconsistencies. His eye was drawn to an apparent discrepancy in the stated metric and imperial height limits at the Broughton bridge – 2.2 metres and 7ft 6 inches.
“I asked Alexa to convert them and and in fact 2.2 metres is just over 7ft 2 inches,” he said. “If 7ft 6 inches is correct, then the metric measurement should be nearer 2.3 metres. It may not sound much but the discrepancy may have be enough to catch out the driver in this case. If that was my van I’d be putting in a claim against whoever put up that sign!”
Alexa’s conversion was accurate and there is a difference between the two measurements. It’s an inconsistency that has snared other drivers in North Wales, notably at a bridge in Penyffordd, also in Flintshire, where several European lorry drivers were caught out by its metric height limit. A Polish HGV driver was even fined after getting his lorry wedged.
Another Flintshire bridge notorious for trapping vehicle is a Cefn-y-Bedd railway crossing where two buses have had their roofs badly damaged. Again, questions were asked when it transpired its height signs didn’t match up.
At the time, Flintshire Council said bridge height conversions are close estimates which makes them easier to read. Which is true – but in reality the explanation is a good deal more complicated.
Dual measurements have been mandatory on road restriction signs since 2016. Older signs only displaying imperial units are rapidly being replaced. It’s led to confusion because of the way in which the clearances are calculated.
If a vehicle is lower than both metric and imperial values, it can legally drive under the bridge. If it’s taller than both values, it can’t. Sometimes however, a vehicle may comply with one of the units, leading to some head scratching.
Providing its initial measurements were correct, Flintshire Council won't be fielding any claims for incorrect signage: everything was done by the book. Of this week’s bridge strike in Broughton, highway network manager Barry Wilkinson said: “We can confirm that the bridge is signed appropriately in accordance with the Road Traffic Signs Manual Chapter 4, which describes the process to be used when providing both metric and imperial measurements.”
In the manual, the Department for Transport makes it clear that both metric and imperial clearance are drawn up separately - they aren’t converted from one to the other. For imperial figures, safe clearances are calculated by subtracting three inches from the bridge height, then rounding down this figure to the nearest multiple of three inches (3, 6, 9) – unless it’s not already a multiple of three. This gives potential clearances of three inches up to almost six inches.
For metric figures, the bridge height is measured to two decimal places. The second decimal digit is then deleted and, if this was seven or less, a further 10cm is lopped off. This leaves clearances varying between 8cm-17cm.
The resulting figures displayed are not the height of a bridge, just the maximum height of a vehicle permitted to go under it. The values may differ but both are compliant with the regulations.
For motorists, theses clearances could be seen to create legal ambiguity – the metric/imperial differences can amount to more than 8cm. But as HGV regulations require drivers to add an extra 15cm to the height of their trucks, trailers or loads, this should give sufficient leeway regardless of metric/imperial clearance warnings.
Similar logic should be applied by owners of vans, motorhomes and caravans – and for cars loaded roof boxes or bicycles. Sat navs and phone apps can help, while low bridge alerting systems are available to HGV fleets. Bridges particularly at risk may have a variable message sign that’s activated by high vehicles passing through an infra-red beam. A few have low beam protectors ahead of the bridge.
Despite this, bridge strikes keep happening and driver error is usually to blame. Online, a Scottish trucker sighed: “Drivers will still hit the bridge regardless of all the warnings on them. Most of the bridge bashes are not a matter of a few centimetres but a substantial difference in height that even a blind horse could see.”