Ottawa Light Rail Transit (OLRT) project (Confederation Line) involves the construction of a new transit facility that will comprise approximately 12.5km of new electrified light rail transit (LRT) between Tunney’s Pasture and Blair Road in the City of Ottawa. The mined tunnel runs from the West to the East Portal at STA 103+149 for 2532m. There are three mined stations along the tunnel route, namely the Lyon Station, the Parliament Station, and the Rideau Station. The paper focuses on the temporary support design of Lyon and Parliament stations. Both stations have a horseshoe section and they are excavated in shallow rock with a minimal cover of soil. In the vicinity of the stations exist high buildings with deep basements, such as Place de Ville and Delta Ottawa Center (Lyon station), and 181 Queen Street, the World Exchange Plaza and 50 O’Connor Street (Parliament station). Both stations are eventually integrated through direct accesses with the existing and future building developments. In order to minimize impact to the existing basements, an innovative tension tie system has been implemented within the tunnels. This paper presents the Finite Element modelling exercises performed for the temporary support design and existing buildings impact mitigation measures for the station caverns that host the Lyon and Parliament stations.

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