Weight restricted bridges
Some of Surrey's bridges are weak and protected by structural weight limits to ensure no damage is caused to them. A structural weight limit (a round sign with a weight limit only) is a mandatory limit meaning vehicles whose plated weight is over the limit must not be driven over the bridge. These are based on plated vehicle weights and the vehicle is banned even if empty.
Bridges can also be restricted by environmental weight limits, applied either to the road on which the bridge lies or to the bridge itself. An environmental weight limit (a weight shown on a lorry on a round sign) is also a mandatory limit. It is to discourage heavy goods vehicles from using the route as a through route. This is either for a social or environmental reason, or because the lane is too narrow.
Height restricted bridges
Bridges, including sign and pipe gantries restrict the available headroom over roads. Only bridges with less than 5.03m (16ft 6in) minimum actual clearance over the carriageway are signed. The signed height denotes the maximum vehicle or load height which can safely travel under the bridge. On arch bridges, the safe area is indicated by a chord line.
Width restricted bridges
Some bridges have width restrictions. These are either due to the physical size of the bridge, or they are used with a weight restriction to ensure that vehicles of a certain size are unable to use the bridge.
To find out where signed restricted bridges in Surrey are situated look at 'Restricted Bridges' (under Roads and Transport) on the Surrey Interactive Map.