The Upper Lachlan Shire Council was forced to revise load limits on 12 timber bridges and three concrete bridges after an assessment by consulting firm Pitt and Sherry on 17 bridges.

Works to build a bypass at Wilcox Road over Clifford's Creek will be completed by Friday, a spokesperson from the council said.

Fisheries permits have now been approved for bypasses to be constructed at the bridge on the Bigga Road spanning Kangaroo Creek, the bridge on the Woodville Road over Crookwell River, Kangaloolah Road over Diamond Creek and the Julong Road bridge over the Crookwell River.

The other bridges which are identified for bypasses have permits which are lodged or the application process has started, except for the Blue Hills Road bypass over Monkey Creek which is being designed.

Steel road plates will be installed over the existing Peelwood Road bridge over the unnamed creek, which does not require a permit. The council now prefers a temporary sidetrack and box culvert bridge at Arthursleigh Road bridge over Sandy Creek. Jeffreys Road over Bridgy Creek is under assessment as a bypass crossing cannot be implemented.

The Roads and Maritime Services is assisting the council to determine if load limits can be increased on bridges where bypasses are not suitable. Consulting firm Xavier Knight are completing technical assessments on the concrete bridges on the Boorowa Road and Reids Flat Road.

Demolition of the bridge at Harley Road over Kiamma Creek began on Monday.