Reports of injuries on a swing bridge on the Great Taste Trail have been “ongoing” and include a cyclist breaking their arm in three places.
The Tasman District Council was presented with a community infrastructure activity report at its operations committee meeting last Thursday.
In the report councillors were told of ongoing reports of rider incidents when crossing the Waimea suspension bridge that traverses the Waimea River in Appleby as part of the Great Taste Trail.
The latest incident allegedly saw a cyclist break their arm in three places.
“I was biking across the suspension bridge across the Appleby River, and it started to sway badly as other people came on, things started to go badly and I was thrown off my bike into the side of the bridge. My arm was caught in the bridges side mesh and my upper humerus is broken in three places”.
“Is there nothing we can do to retrofit it to make it [safer]?”, deputy mayor Stuart Bryant asked transportation manager Jamie McPherson during the meeting.
“It’s been quite a lively bridge, that incident its the first time a report has really prompted us to look harder,” Jamie says.
He says there are some things that can be but affordability needs to be looked at.
“They’re always going to be lively strcutures, we’re not going to be able to remove liveliness altogether, it comes down to cost and the benefit.”
Physical elements to stiffen the bridge, such as the torsion bar that was incorporated in the latest Baton Bridge design, have been considered but not progressed due to the significant cost.
Council set up a test to measure side to side and vertical accelerations and rotational velocity (roll) of the deck while two “energetic teenagers” on mountainbikes did their best to “get the bridge excited”.
The measurements confirmed that rotational roll is likely to be the key issue.
A proposed solution was then tested by string tying the bridge hangers (vertical cables) to the handrail stanchions and this saw a significant improvement.
The tested intervention was especially effective where the suspension cable crosses the handrail, and moderately effective around bridge midspan and where the hangers are longer, therefore more compliant.
Additional warning signage will be installed, recommending cyclists walk their bikes across the bridge.
