Life Cycle Assessment of the Byåsen tunnel in Trondheim, Norway - Assessing emissions from traffic and infrastructure

The Byåsen tunnel is a tunnel proposed by the Norwegian Public Roads Administration (NPRA), and an infrastructural element in an environmental programme (Greener Trondheim) initiated by the Trondheim municipality, Norway. Among the main goals is an overall decrease in CO2 emissions from traffic. This study assesses the environmental impacts (expressed in greenhouse gases) induced by the construction of the tunnel and emissions from traffic in operation. Additionally, the study gauges its coherence with goals set in the Trondheim municipality s environmental programme. The study utilizes LCA methodology, including regional traffic data and parameters pertaining to routes travelled by vehicles included in the study. The project s environmental impacts are between 73.738 77.851 thousand ton CO2-eq/year, depending on tunnel design (length), and 80.516 thousand ton CO2-eq/year for the reference scenario, with no tunnel constructed. Net GHG-emissions related to the excavation and operation of a tunnel in excess of 2 km proves to be between 3106- 5509 ton CO2-eq/year depending on design, which is about 6% of yearly emissions from traffic. A simulation of traffic volume (after excavating the Byåsen tunnel) without tolling reveals an increase of 7715-8040 ton CO2- eqs/year. This is a 10% increase in traffic emissions from tolled tunnel alternatives. The results found in this study shows that the construction of the Byåsen tunnel leads to a net decrease of 2665-6778 ton CO2-eq/year. That is a net decrease of 3.3-8.4% over the reference alternative. This study does also show the importance of including traffic in operation when assessing infrastructure as well as the significant effect tolling stations has on traffic volume and yearly GHG-emissions