Environmental impact of drill and blast tunnelling: life cycle assessment

•We examine the environmental impacts of drill and blast tunnelling.•We analyse the influence of tunnel size and length on those impacts.•Main data stem from the tunnelling practices in Norway over last 20 years.•The three main sources for all impacts are explosives, diesel and electricity.

This paper explores the environmental impacts of drill and blast tunnelling by life cycle assessment. In order to understand the potential of cleaner tunnelling, this paper also analysis the influence of tunnel length and size on pollutant emissions. The excavation practices of rock tunnel in Norway over past 20 years are used to estimate material, equipment and energy consumption. The background data are drawn out from various databases in the Simapro software.The results indicate that: 1) the most important contributor to the climate change and terrestrial eco-toxicity impacts are the loading and hauling process. Its relative contribution also increases when the tunnel becomes bigger or longer. 2) The drilling and blasting process is the dominate contributor to the human toxicity, photochemical oxidant formation, particulate matter formation and terrestrial acidification impacts. The relative influence of this process, however, slightly decreases when tunnels become bigger or longer. 3) The three main sources for all impacts are explosives, diesel and electricity. Therefore, a significant potential of environmental impacts reduction could be reached by optimising drilling and blasting operation to reduce explosive consumption, and by improving renewable energy sharing.