A multi-agency emergency training exercise is planned for the Tamar Bridge, which connects Devon and Cornwall.
Tamar Crossings, National Highways and emergency service partners will run the exercise from 19:30 BST on the bridge over the River Tamar between Saltash and Plymouth.
The bridge was chosen because of its "unique characteristics, operational requirements and importance to the regional transport network", Tamar Crossings said.
The bridge is expected to stay open throughout the exercise, with arrangements to keep access for vehicles, pedestrians and cyclists.
Tamar Crossing said appropriate safety measures would be in place throughout and all activity would be carefully managed by the organisations involved.
Bridge manager Coral Jonas said: "Exercises such as this are an important part of ensuring we remain prepared to respond effectively should an incident occur on the bridge network. By working together with our partners in a realistic setting, we can test our procedures, strengthen coordination and continue to prioritise the safety of everyone who uses the Tamar Bridge."
She encouraged travellers to allow extra time, follow any temporary traffic management measures and check for the latest travel information before setting off.
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Tamar Bridge to Host Multi-Agency Training Exercise