How to measure a bridge crossing

Measure the bridge length from the edge of one bank to the edge of the opposite bank, adding a minimum of 2 metres.
This allowance provides approximately 1 metre of bridge length beyond each bank edge.

Bison bridges are stocked in 1-metre increments, so selecting the next full size (for example, an 8-metre bridge instead of a bespoke 7.8-metre unit) is often more cost-effective.