In recent years the semi-rural Thomas/Gordonton intersection has become increasingly busy, used by around 16,000 vehicles per day. Between January 2017 and January 2018 there were 19 crashes leaving locals and Hamilton City councillors united in the need to do something. Finding an effective fix was a matter of life or death and WSP worked closely with Hamilton City Council and the NZ Transport Agency to deliver a solution.
Letitia Garmonsway, WSP Transport Engineer, says there was an urgent need to slow traffic down at the intersection.
“The single biggest factor in the seriousness of a crash that causes death or serious injury is speed. In an ideal world accidents and crashes wouldn’t happen, but they do because people make mistakes. What we can to do is put measures in place to ensure people survive those mistakes.”
Robyn Denton, Hamilton City Council’s Transportation Network Operations and Use Leader, says this is one of the city’s busiest and was one of the highest risk intersections in terms of safety performance. This upgrade will enable the intersection to cope with traffic flows better while also supporting the Council’s Vision Zero aspiration — the philosophy for road safety to achieve zero road deaths and serious injuries within Hamilton.
“In order to move towards our Vision Zero goal, it is our responsibility to provide a more forgiving roading network, so when mistakes are made the consequences aren’t as severe. It’s because of this philosophy we fast-tracked the upgrade at the Thomas Rd/Gordonton Rd intersection,” says Mrs Denton.
In October 2018 the speed limit on the approach to the intersection was reduced from 80kph to 60kph as part of the Gordonton Road Corridor study, but it was clear that a bigger intervention at the Thomas Road intersection was required.
Letitia says the obvious solution to slowing traffic was to install a roundabout. However, site restrictions, and the urgency for safety improvements, meant it wasn’t a viable short to medium term solution for the intersection.
“Roundabouts are ideal because traffic slows down on approach and all vehicles travel in the same direction. However, it can take a couple of years to put in a suitably sized roundabout by the time land is purchased, consents granted and essential infrastructure is relocated,” she says.
Given the level of risk the intersection posed to human life it was decided to trial an innovative new approach.
The trial was developed by the National Safer Intersections Working Group, which includes representation from the NZ Transport Agency and local government authorities – in this case, Hamilton City Council.
As a result traffic lights were installed along with raised safety platforms (RSP) on the high speed approaches to slow traffic to 50kph or less.
While RSPs have been used at pedestrian crossings, Letitia says they’ve never been used to slow traffic at intersections in New Zealand. They have been successfully trialled overseas however.
When constructed at more than 40 signalled intersections in the Netherlands the result was a 40-50% drop in fatal and serious injury crashes. VicRoads in Australia has also begun using RSPs as one of its Safe System treatments. Safety specialists from WSP Opus Research provided additional guidance to the project team on the suitably of installing RSP’s at the site given the history of high approach speeds. Computer simulations were also conducted to ensure the proposed WSP Opus design did not cause heavy vehicles to roll.
Given this is the first use of RSPs in this context, the upgraded Thomas/Gordonton intersection will be closely monitored by the National Safer Intersections Working Group and may lead to wider implementation as part of the NZ Transport Agency’s safety intervention toolkit.
Monitoring shows that speeds have already reduced at the intersection and locals are reporting safer driving behaviour.