A sinkhole has appeared in the Oamaru Creek bridge in Humber St.
The sinkhole developed in the abutment at the southern end of the bridge last week, Waitaki District Council roading manager Mike Harrison said.
The road has been temporarily repaired, but the council was assessing its options for a more permanent solution, Mr Harrison said.
“Our initial investigation [found] it was a hole that had opened up, where the creek had actually washed away some of the road foundation,” Mr Harrison said.
“We are not really sure what is causing the problem, so we have taken a conservative approach to give us time to understand the issue, come up with a solution and keep the road open.”
In the meantime, the speed limit had been reduced to 30kmh and judder bars had been installed to mitigate the impact vehicles were having, Mr Harrison said.
“We are trying to keep the road open, so the community support is really important. They can help by going slowly, because if it comes back again we will have to close the road.”
If the problem persisted, the road would have to be repaired from below the bridge, he said.
Complicating matters was the close proximity of the creek and overhead railway viaduct.
“We need to be clear about what we are going to do and look at our resource consents,” he said.
“We could drill a hole through and fill it up with concrete, but if the concrete was to leach into the water, there would be an unfortunate environmental impact.”