Metro Vancouver residents could learn what a likely Massey tunnel replacement option will look like early Wednesday afternoon.
The George Massey Crossing Task Force will receive a report about six short-listed replacement options for the aging tunnel. The task force was started after the NDP scrapped the previous Liberal government’s 10-lane bridge proposal.
The report highlights the advantages and disadvantages of the six options:
- New eight-lane immersed-tube tunnel with multi-use pathway
- New six-lane immersed-tube tunnel plus use of the existing tunnel to provide two dedicated lanes for transit.
- New eight-lane bridge with multi-use pathway.
- New eight-lane deep-bored tunnel plus use of the existing tunnel for a multi-use pathway.
- New six-lane bridge plus use of the existing tunnel to provide two dedicated lanes for transit.
- New six-lane deep-bored tunnel plus use of the existing tunnel to provide two dedicated lanes for transit.
It notes the deep-bored tunnel options are “technically challenging and are assessed as high risk.” This option would risk sink holes appearing and require “removal of three million cubic meters of salt-contaminated soil during construction.” The cost is estimated at three times the cost of the immersed-tube tunnel and bridge options. The report points to the Alaskan Way Viaduct replacement tunnel project in Seattle, which finished late and overbudget after a boring machine, dubbed Berta, got stuck multiple times. The machine needed for the Massey project would be 20 metres wide, compared to 17.5 metres for the Seattle project.
The immersed-tube tunnel options are described as “moderately challenging,” with the most complex environmental assessment due to in-river and riverbank work. This option would require one kilometre of tunnel, a large staging area and removal of 1.5 million cubic meters of salt-contaminated soil. It’s estimated to cost the same as a bridge option, although costs are not yet known. The 10-lane bridge option was estimated to cost $3.5 billion.
The bridge options would require the least complex environmental assessment, the report notes, as it would be similar to the one already done for the 10-lane option. It would require around three kilometres of bridge and approaches, with abutments on land and foundations of at least 80 metres in depth.
The current tunnel, although expected to remain “serviceable” for 50 years, does not meet seismic requirements, the report said.
The task force is expected to come to a decision that will serve as its recommendation to Metro Vancouver mayors Wednesday afternoon, although it will not be binding.