The Infrastructure Projects Authority (IPA) has published the first study to benchmark tunnelling costs and production rates in the UK in a bid to better “articulate desired outcomes”.
The IPA launched the project in June and worked in collaboration with the British Tunnelling Society (BTS) and industry to compare the cost, schedule and performance of projects against other similar projects.
According to the research, the principle drivers of cost across both transport and utility tunnels are length and diameter rather than ground conditions.
IPA director of infrastructure delivery Stephen Dance commended the industry collaboration that made development of the benchmarking document possible. “The fact that wide diameter tunnels cost more than narrow diameter tunnels is not a surprise but the project sets a baseline for the industry,” he said. “The most positive aspect is not the outcomes from the project, but the industry collaboration that has made it possible to collect, measure and publish the data.”
The project is the first in a series of benchmarking exercises that the IPA has planned. According to the IPA, tunnels were chosen as they have been successfully benchmarked in the past and allowed effective testing of the IPA’s methodology.
Through a forum with the BTS, industry stakeholders from multiple sectors came together to share information on tunnelling costs, with additional data provided directly from a range of departments, sponsors and programmes which are involved in tunnelling activities.
The benchmarking was initially based on 169 projects but the more detailed analysis focused on 16 projects in ranging ground conditions from soft rock to cohesive and non-cohesive soils, as well as construction methods.