Ashburton District Councillors are still not sold on a heavy vehicle weigh station on the north bank of the Rakaia River, despite safety assurances by police and the NZTA.
NZTA is proposing to drop the speed limit from the southern end of the Rakaia road bridge to the northern end of the overbridge to 80km/h.
Rural intersection active warning signs, like on SH1 at Burnham, would further reduce the speed limit to 70km/h or 60km/h when trucks were entering and exiting the weigh station, councillors were told last week.
The weigh station is planned on land on the eastern side of the northern end of the bridge; up to eight trucks an hour are expected.
Councillors are concerned that slow-moving trucks entering and exiting the weigh station will cause accidents and bottlenecks on the bridge, an important north-south link.
NZTA's Graham Taylor said the Rakaia station would be one of 12 and aimed at catching overweight vehicles. Being overweight affected their ability to brake safely and was a road safety issue.
He said about 40 per cent of loaded trucks were overweight, though it varied around the country.
Often offending vehicles belonged to a small number of operators, who were then able to be visited and asked to improve compliance.
Rakaia is considered ideal because no trucks can escape detection if they are crossing the Rakaia River on SH1. On other parts of the highway, there were side roads to take to avoid the station.
Onsite, there is a permanent speed limit reduction proposed,Taylor said.
The active warning signs also raised drivers awareness that something was happening.
He said the site had been visited by safety auditors and traffic assessors, who proposed lowering the speed limit. A roundabout was also suggested, but dismissed because of costs and the possibility of adding delays.
Heavy trucks on the highway have their number plates scanned leading up to the site, the information is matched to online weight data and select vehicles are ordered to pull off into the site for weighing.
Acceleration shoulders would help them return to the highway and rejoin traffic safely.
Mr Taylor said the weigh station would have an operating plan that would take into account when highway traffic was unusually busy. It might not be practical to signal trucks to pull over during those times.
Mayor Neil Brown said a weigh station in Rakaia was a safer site as councillors and local police did not like the proposed site. NZTA has asked to use land on the southern side of the bridge for a weigh station sign alerting drivers if they had to pull over for weighing.
NZTA will provide council with the experts' safety reports.
