1 August 2018
Traffic pattern surveys
We have completed an extensive and intensive survey of traffic patterns between Te Atatu and Swanson to obtain an up-to-date understanding of the traffic patterns in the area, that generates traffic that uses Lincoln Road.
We also have sensors around a smaller area that can measure the travel times of vehicles on Lincoln Road and other surrounding main routes (at peak times most are trying to access or return from, the motorway).
The combined data will allow us to construct up-to-the minute models for a range of scenarios. For example:
- how the current traffic is behaving within the existing network.
- how traffic will be impacted by different construction and traffic management methodologies. This will identify the least disruptive methodologies and also how to minimise the impacts.
- how well the road will perform when it is upgraded. Previous studies were made before the causeway and Te Atatu Road were upgraded, the Waterview Tunnels were opened and there were significant improvements in Public Transport. The new data will be up-to-the-minute and identify what changes may need to be made to the road’s design.
Optimising the transit lane
The data will also help us to model the best possible use for the new Transit lanes, will help us decide whether the lanes are:
- bus only.
- T2 with buses.
- T2 with buses and trucks.
- T3 with buses or with buses and trucks.
Soil contamination survey
Soil contamination tests were made throughout the project area in 2015. No serious contamination was found except at obvious locations (e.g. petrol stations) and there will be plans for the removal and safe disposal of any contamination during construction.
Next steps – exploring what’s under the surface
In July a 20 to 26 week programme started exploring the structure of the soils supporting Lincoln Road and the strength of the road itself. It will also cover finding where the underground services are and where they can be moved to.
Services are found by trenching and using ground penetrating radar. By opening the ground we can see exactly where the services are. The narrow (0.5 metre) trenches will be dug at intervals and ground penetrating radar will be used in the space inbetween. The trenches will be limited to the berm, but there may be a requirement that some will be in the road, tracing services that cross from one side to the other.
Most trenching work will be done at night with the ground re-instated in time for morning traffic and business activities. Reinstating the ground each night means we work will take longer theb usual.
Soil structure testing
Testing involves taking core samples to map the strength and composition of the soils on which the road is built on. This will reveal whether the soil can bear the weight of the current largest vehicles or if any of the underlying area needs to be strengthened. It will also guide how strong foundations need to be, for retaining walls that will be built at many places on property boundaries.
Finally, it will also tell us if more drainage is necessary.
Pavement is the road structure itself, the materials that form the foundations and the asphalt on top. Testing combines core samples and special machines designed for the purpose. Both road building standards (strength and length of life) and the size of heavier vehicles have increased in recent times and this data will reveal whether the pavement strength is strong enough as is, or needs to be greater.