The Tinwald Viaduct shows the signs of numerous incidents where oversized vehicles have hit the bridge, making it the second-most hit bridge in the country in the last two years. Photo: LDR / Jonathan Leask
The Tinwald Viaduct shows the signs of numerous incidents where oversized vehicles have hit the bridge, making it the second-most hit bridge in the country in the last two years.
Three times a year a driver will crash into the Tinwald viaduct which authorities say is clearly signposted.
The viaduct on Melcombe Street in Tinwald, the suburb on the southern end of Ashburton, passes under the railway line and has a height restriction of 2.39m but three times in each of the last three years it has been hit by oversized vehicles.
KiwiRail said it is the second most-hit rail bridge in the country over the last two years.
The most hit bridge is in Taumarunui and that has had 34 bridge strikes since 2004.
A KiwiRail spokesman said the incidents were mostly camper vans or small vans, not commercial trucks "who probably know to avoid the bridge and are more aware of their vehicle height and height restrictions".
The bridge's height restriction had adequate signage and advanced warning signs which were the responsibility of the local roading authority, the spokesperson said.
Ashburton District Council infrastructure and open spaces group manager Neil McCann said the existing warning signs were clear but the council and Waka Kotahi NZ Transport Agency were looking at ways to improve road safety around the Tinwald viaduct.
"We plan to increase the size of the signage across the top of the viaduct arch to make it more visible," McCann said.
"A new sign informing of the height restriction is proposed to be installed on Melcombe Street for those approaching the viaduct from the west as part of Waka Kotahi's State Highway 1 Tinwald Corridor Improvements project."
The warning signs for the height restriction at the Tinwald Viaduct are deemed adequate but further safety improvements are being investigated. Photo: LDR / Jonathan Leask
The warning signs for the height restriction at the Tinwald Viaduct are deemed adequate but further safety improvements are being investigated.
Whether any further signage pointing to the height restriction would be installed on SH1 was a decision for Waka Kotahi McCann said.
"One factor we believe might be contributing to issues is that GPS navigation may be directing drivers to Melcombe Street and the viaduct to avoid congestion on SH1.
"We have reached out to a commonly-used mapping service and, while it is outside of council's direct control, we hope that the height restriction will be noted on that navigation service in the future."
When a rail bridge gets hit the KiwiRail spokesperson said the driver should call the 0800 number which was on each of KiwiRail's bridges with the bridge number and line quoted on it.
Once train control, which is monitored 24/7, received the call they contacted the local structures inspector and would stop all trains from going over the bridge.
Once KiwiRail staff have inspected the bridge for safety, train control can allow trains to go over the bridge the spokesperson said.
An engineer's report is also completed by a third party at a later date to confirm if any repairs are required, he said.
Two way access
In the latest plans for the Tinwald Corridor Upgrade, due to start later this year, the Melcombe Street viaduct will remain open to two-way traffic.
It had been proposed to be limited to left-out only onto SH1 and Waka Kotahi director regional relationships James Caygill said the change was made following public consultation but it would be monitored "to maintain that works".
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