Work on the roundabout at the intersection of South St and Chalmers Ave would need to be completed in stages and was expected to take about six months, NZ Transport Agency's second bridge project director Lonnie Dalzell said.
“This phase is particularly complex due to high traffic volumes, disruption to existing services, the need to redesign the current intersection, and the challenges posed by winter weather.
“Notably, this roundabout can be built largely independently from the other project activities, allowing it to be completed and opened to the community ahead of the remaining works.
“This approach delivers immediate benefits for residents and road users, addressing safety and traffic flow concerns well before the larger project concludes.”
The intersection has an unusual offset crossroads and a dog leg, where Chalmers Ave, with two lanes divided by a grassed median, does not line up directly across South St where it narrows to two lanes without the grass verge.
“We are redesigning the current layout to enhance safety and ensure that all vehicle types can turn safely and efficiently,” Dalzell said.
The contractors are also having to realign a stormwater pipe at the river end of Chalmers Ave, and the council is taking the opportunity to install a new watermain that will run from there all the way to Grahams Rd.
As well as the roundabout, “multiple activities” are under way now that main construction works have begun, including starting on the bridge construction, he said.
That includes work on the 24 piles on the Ashburton side of the riverbed embankment, with a further four on the Tinwald side.
One of two large cranes is already onsite in preparation for piling in mid-June that will take about eight months.
The entire project, the new bridge and the connecting road to Grahams Rd, is scheduled for completion at the end of next year.
Dalzell said there is an overall construction programme that “provides indicative timing for all activities”.
“However, as works progress these activities and timings can change. Notice will be provided to residents, road users, and the wider communities prior to works commencing.”
Rail footbridge renovation
Across town another bridge is getting worked on.
The historic 109-year-old rail footbridge in the centre of town is now closed to the public for a major renovation.
The Railway Footbridge, with its bowstring truss, is the only remaining bridge in New Zealand of its type in its original location and used for the original purpose.
The refurbishment is estimated to cost about $880,000 and comes under the council’s existing budget for maintenance and renewal work on local bridges and structures, and is partly-subsidised by NZTA.
Infrastructure group manager Neil McCann said the 25-metre central iron truss is scheduled to be removed by crane on June 8, weather permitting.
“The truss will be lifted off and placed onto KiwiRail land to the south of the footbridge, on the West St side.
“It will be repaired and repainted, and then lifted back onto place. The ramps and supports on either side of the footbridge will also be repaired and restored.”
The footbridge is planned to be closed until the end of October, but it will open sooner if the works are completed earlier, he said.
- By Jonathan Leask, Local Democracy Reporter
