The 200-year-old Ivinghoe Bridge, near Cheddington, is to be repaired and strengthened following a structural review.
The bridge on the B488, also known as Brownlow Bridge, was closed throughout last summer after it was hit by a vehicle in the early hours of the morning on Monday, May 21.
Repairs were originally planned for January, but have been rescheduled to start in the autumn after an ecological survey identified possible bat nesting sites. Further bat surveys will now have to be done during the breeding cycle until September.
The Canal and River Trust (C&RT), which owns the bridge, undertook a review following concerns about its structural condition.
Bucks County Council - which checked C&RT's findings - agrees the bridge is only strong enough to handle traffic loads of up to 18 tonnes, and a temporary weight restriction has been imposed on the bridge to protect it from further weakening.
This weight restriction will remain until the strengthening repairs have been completed.
Cllr Paul Irwin, deputy portfolio holder for transport on Bucks County Council, said: "Transport for Buckinghamshire (TfB) will increase the frequency of their structural inspections.
"In addition to the Canal and River Trust inspections, we'll have a much clearer picture of the bridge's condition to check it doesn't get any weaker.
"I've met with a number of local people who are concerned that the bridge is being used by heavy lorries. I understand these concerns, which is why we've been considering ways to enforce the 18 tonne limit, and why we're moving as quickly as we possibly can within the scope of ecological legislation to start strengthening work."
Cllr Irwin said the bridge works were being considered in tandem with a proposed longer-term area-wide plan for handling heavy lorries.
The £100,000 cost of repairs will be met from TfB's structures fund.
The C&RT is statutorily required to maintain the bridge, a Grade 2 listed structure, to carry a maximum nine-tonne weight.
But as it forms part of Buckinghamshire's road network, requiring a higher weight limit for traffic, it falls to the County Council to oversee its maintenance.