George Massey Tunnel, opened to traffic in 1958, carries two lanes of traffic each way under the Fraser River. The 629 m (2064 ft.) long immersed tunnel comprises six precast units, each approximately 105 m (345 ft.) long, which were floated into position and sunk into a trench in the loose sand of the river bed.
The approach structures consist of reinforced concrete retaining walls, which are about 350 m (1148 ft.) long on each side of the ventilation buildings. The tunnel, which was designed with little consideration of seismic response, is located in an area of seismic hazard and is underlain by estuarine sediments about 600 m (1969 ft.) deep over bedrock.
Buckland & Taylor was retained, in 1999, to prepare a seismic assessment of the structure, to identify its seismic vulnerabilities and to establish feasible seismic retrofits and costs. This work was completed by March 2001.
In May 2001, Buckland & Taylor was selected to prepare the final design for the Seismic Safety Retrofit. Subsequently, the Ministry of Transportation (MoT) decided to upgrade the pumping and emergency power system and Buckland & Taylor Ltd. performed this work.
The structural retrofit construction was completed in 2006. Upon completion of the structural retrofit, MoT decided not to proceed with the ground improvement (based on a second value engineering exercise taking into consideration a new plan of replacing the tunnel with a new crossing in the next 20 years).
In 2008, a study was performed to estimate the level of earthquake that the structurally retrofitted tunnel could tolerate without life safety damage, under the current conditions without any ground improvement.
Hisham Ibrahim, P.Eng.
Vice President, Technical Director
Tel: +1 604.986.1222
Seismic assessment, seismic retrofit design, design of pumping and emergency power system, value engineering andconstruction services
Government of British Columbia
Phase I - Structural $19.5 MPhase II - Geotechnical $20 M (cancelled)