A 1980s computer model of London's Grade II listed Battersea Bridge could hold the key to efforts to reopen the structure after it was damaged by a barge last week.
The outer cast iron ribs supporting the second 49m span of the five-span crossing suffered serious cracking and loss of section.
'The bridge was strengthened in the late 1980s to bring it up to the new 40t weight limit, ' said Transport for London chief engineer Dana Skelley.
'We will try to use the finite element analysis model used to develop the strengthening operation to see what loads it can take in its current damaged condition.
'We need to establish as soon as possible if we can allow some light traffic across, ' she said.
The damage occurred on 20 September when a near empty 200t gravel barge struck the bridge at high tide and became lodged underneath. The bridge has been closed to road traffic ever since.
There was also non-structural damage to the cast iron balustrades, but the five central arch ribs were unscathed.
Replacing the damaged ribs could take months and involve 'lots of falsework', Skelley added.
An investigation as to how the 200t gravel barge came to get stuck under the bridge is under way.