More seismic improvements are planned for the silver bridge in Duncan.

Seismic 2000 Construction is working to make the silver bridge safer in the event of an earthquake.

Between May 3 and May 9, the southbound Truss Bridge and northbound Arch Bridge will be closed for 10 to 30 minutes at a time between midnight and 4 am.

The bridge will be closed to one direction of traffic at a time.

Trucks carrying loads of 80 or more tonnes will need to follow the detour route.

Traffic is asked to obey the 50 kilometres an hour speed zone to ensure the safety of workers.