The contents of the KiwiRail consultant engineers’ report have been revealed after an Official Information Act request from The Ashburton Courier.
"We would recommend that the road beneath the bridge is closed to motorists until the impact protection structures can be restored to a suitable level of protection.
"This would eliminate the risk of a catastrophic incident occurring until the risk can be reduced through other means of mitigation," the engineers said.
The crash was on June 30, when the bridge was struck by an excavator being towed on a trailer.
The KiwiRail consultant report is dated July 3, but the bridge was not closed for repairs until July 29, as the Ashburton District Council developed a traffic management plan.
During this almost four-week window, the bridge was struck again on the opposite side by a motorhome on July 22.
The bridge is the most struck bridge in New Zealand, with 13 reported strikes in the five years prior.
The Courier asked the district council why it took so long to do a traffic management plan.
Group manager infrastructure Neil McCann said while the report highlighted an increased risk to the bridge’s structure "a full risk assessment deemed the likelihood of another similar strike in the short term as low so therefore not urgent".
"This allowed time for us to work with KiwiRail and NZTA to develop and implement a suitable traffic management plan that then eliminated risk for all road users over the long-term," McCann said.
"Had another strike occurred, the road would have been closed immediately."
Made aware of the other strike by the motorhome on July 22, McCann said: "The road wasn’t closed because the protective beam on that side was still intact and not damaged by the strike by the excavator."
Meanwhile, repairs are yet to begin on the bridge.
A KiwiRail spokesperson said the rail authority had completed a design for repairs and was currently in the process of selecting a suitable contractor.
"While we understand this road detour is inconvenient for the Ashburton community, this is a complex piece of work due to the bridge being a heritage structure.
"We are working closely with Heritage New Zealand to ensure the work can be carried out as soon as possible.
"Meanwhile, the bridge remains open for trains with a speed restriction in place."
KiwiRail was unable to provide an updated timeline for reopening of the bridge.
Considering the initial timeline of repairs of six to eight months, the bridge is due to reopen anytime from January to March.
