When Metro Vancouver residents think of local major transportation tunnels, they are most likely to think about the various SkyTrain tunnels across the region, Highway 99’s George Massey Tunnel across the Fraser River between Richmond and Delta, and Highway 1’s Cassiar Tunnel near Hastings Street on the border of Vancouver and Burnaby.
Nestled deep beneath the growing towering urban jungle of Brentwood Town Centre lies a transportation tunnel that is well known to many Burnaby residents, but is often overlooked by many other Metro Vancouver residents.
With a length of 3.2 km, the Thornton Tunnel in northwest Burnaby — an active single-track freight railway tunnel owned and operated by Canadian National (CN) — is Metro Vancouver’s second longest transportation tunnel, only surpassed by SkyTrain Canada Line’s 9.1-km-long continuous tunnel underneath the north-south length of Vancouver.
The Thornton Tunnel branches off northwest from CN’s east-west trunk railway through Burnaby, starting near Willingdon Avenue and Costco. The tunnel’s south entrance is located on the south side of Dawson Street between Madison and Rosser avenues, with the perimeter of the railway fenced off and now largely visually obscured by tall trees and thick bush growth.
Thornton Tunnel between the Second Narrows of Burrard Inlet and Brentwood Town Centre district in Burnaby. (Vancouver Fraser Port Authority)
The diagonal outline of Thornton Tunnel between the Second Narrows of Burrard Inlet and Brentwood Town Centre district in Burnaby can be seen in Google Maps. (Google Maps)
The area surrounding the tunnel’s south entrance is in a state of change, with its traditional industrial uses increasingly making way for redevelopment into the high-rise mixed-use towers of the Brentwood Town Centre district.
The various residential buildings immediately to the north have clear setbacks away from the areas of the lots that are directly above the segments of shallow tunnel, with these spaces strategically used as landscaped outdoor amenity spaces.
The eastern part of the lot of the 2018-built eight-storey condominium building of “Madison & Dawson” at 2188 Madison Avenue is a private outdoor amenity area for residents for this reason.
Further to the north, the 2005-built Renaissance condominium towers at 2088 Madison Avenue have used the southwest corner of the property — where the tunnel crosses through the site — as a large landscaped area.
Route of the Thornton Tunnel cutting through lots within Brentwood Town Centre district, with the tunnel’s south entrance shown. (BC Assessment)
Aerial of Brentwood Town Centre district developments shaped by the underground route of the shallow Thornton Tunnel, with the tunnel’s south entrance shown. (Google Maps)
The south entrance of the Thornton Tunnel in Brentwood, and landscaped areas for where the tunnel runs through adjacent residential lots. (Google Maps)
Landscaped outdoor amenity space at the “Madison & Dawson” condominium building at 2188 Madison Avenue to accommodate the shallow depth of the Thornton Tunnel. (Google Maps)
Landscaped outdoor amenity space at the Renaissance condominium towers at 2088 Madison Avenue to accommodate the shallow depth of the Thornton Tunnel. (Google Maps)
From this area, the tunnel makes a straight line in the northwest direction towards the Second Narrows of Burrard Inlet.
North of the initial residential properties impacted within the Brentwood area, the tunnel runs directly under the Staples store on Lougheed Highway, Pacific Heritage Cemetery, and Willingdon Community Centre and Willingdon Heights Park, before crossing under the single-family neighbourhoods of Willingdon Heights and Burnaby Heights.
Thornton Tunnel’s north entrance is located at Bates Park overlooking Burrard Inlet, immediately east of the Ironworkers Memorial Bridge. At this site, the tunnel immediately transitions into the Second Narrows Rail Bridge.
The combined railway corridor segments of the Second Narrows Rail Bridge and Thornton Tunnel were completed in 1968 and 1969, respectively.
The bridge and tunnel completions in the late 1960s bookended a decade-long construction period of major transportation projects across the North Shore, beginning with the construction of the Ironworkers Memorial Bridge between 1957 and 1960, which was marred by the deadly collapse in 1958 killing construction workers.
The south entrance of the Thornton Tunnel in Brentwood. (Kenneth Chan/Daily Hive)
The south entrance of the Thornton Tunnel in Brentwood. (Kenneth Chan/Daily Hive)
The south entrance of the Thornton Tunnel in Brentwood. (Kenneth Chan/Daily Hive)
The south entrance of the Thornton Tunnel in Brentwood. (Kenneth Chan/Daily Hive)
The four-lane Upper Levels Highway across the North Shore — between BC Ferries’ Horseshoe Bay Terminal in West Vancouver to the Ironworkers Memorial Bridge — reached completion soon after in 1964, and was originally named Highway 401 before being later renamed as a part of Trans-Canada Highway (Highway 1).
The Thornton Tunnel’s railway corridor through Burnaby reaching the North Shore is the only rail connection to transport goods and commodities to and from the port terminals in North Vancouver, including vital national supply chains to global markets for products such as grain and fertilizer.
According to the Vancouver Fraser Port Authority, the railway corridor between the North Shore and Brentwood moves over 40 million metric tonnes of export cargo, accounting for over 40% of the port’s total international exports in 2023.
The Second Narrows Rail Bridge just beyond the north entrance into the Thornton Tunnel. (sophiecat/Shutterstock)
The Second Narrows Rail Bridge just beyond the north entrance into the Thornton Tunnel. (Google Maps)
In 2022, as part of the broader Burnaby Rail Corridor Improvements Project (BIRP), CN completed two capacity-related projects to boost the Thornton Tunnel’s capacity and frequency for handling freight trains. This included a new rail siding track in the Brentwood area from Willingdon Avenue to Piper Avenue, parallel to existing tracks, to stage trains accessing the Thornton Tunnel, and major upgrades to the Thornton Tunnel ventilation system to reduce the time between trains travelling through the tunnel.
The tunnel’s optimal capacity entirely depends on its ventilation system, as the manned trains can only safely enter the tunnel after the fossil fuel-powered locomotive exhaust is cleared for the net train. Prior to the 2022-completed upgrades, it took about 20 minutes for the ventilation system to clear the air of the 3.2-km-long tunnel.
According to a 2019 railway capacity study commissioned by the port authority, the BIRP strategy’s ventilation upgrades to the Thornton Tunnel reduced the tunnel ventilation time from 20 minutes to 10 minutes tail-to-tip headway.
The average travel time, including the waiting time for purging exhaust fumes from the tunnel, will drop from about 47 minutes to 34 minutes from not just the tunnel ventilation upgrades, but also from a 30% shortening of the railway corridor’s signal block length to 4.9 km as a result of signal block upgrades.
The average railway traffic demand is expected to rise from about 14 trains per day in 2018 to 25 trains per day by 2030. The average railway capacity will climb from about 20 to 30 trains per day to 26 to 41 trains per day after the upgrades, with the varying ranges accounting for the frequency of the Second Narrows Rail Bridge — a vertical-lift bridge — opening up to enable ship traffic to pass through.
Map of the Burrard Rail Corridor Improvements Project. (Vancouver Fraser Port Authority)
The maximum operating speed of 10 mph (16 km/hr) for the entire length of the railway corridor between Brentwood and the North Shore is unchanged.
Railway tunnels harness the aerodynamic airflow generated by fast-moving trains to help fulfill their ventilation requirements, but that is not a strong factor for the Thornton Tunnel due to its low train speed restrictions along with the use of fossil-fuel powered locomotives.
For this reason, the Thornton Tunnel has a major ventilation shaft and exhaust repulsion fan system almost exactly at the mid-way point of the tunnel.
The powerful ventilation equipment is located at the northeast corner of the intersection of Ingleton Avenue and Frances Street, carrying the address of 3911 Frances Street — about 20 storeys or 62 metres (203 ft) directly above the tunnel.
To the casual observer, the ventilation building of the Thornton Tunnel in Willingdon Heights could easily be mistaken for a traditional single-family home, seamlessly integrated into its low-density residential surroundings to maintain aesthetic harmony. That nondescript appearance, as opposed to a heavy industrial building that sticks out like a sore thumb, is of course highly strategic.
Location of Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (Google Maps)
Location of Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (Google Maps)
Location of Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (BC Assessment)
Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (Kenneth Chan/Daily Hive)
Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (Kenneth Chan/Daily Hive)
Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (Kenneth Chan/Daily Hive)
Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (Kenneth Chan/Daily Hive)
Thornton Tunnel’s ventilation building enclosed inside a fake house at 3911 Frances Street, Burnaby. (Kenneth Chan/Daily Hive)
February 2022 construction work to upgrade Thornton Tunnel’s ventilation capacity at the fake house at 3911 Frances Street, Burnaby. (Kenneth Chan/Daily Hive)
Records show this ventilation building was constructed in 1982, and the lot it sits on is roughly equivalent to the size of two standard single-family lots.
In addition to the bungalow-style appearance, the building and its exhaust vents are concealed by hedges, and multiple trees that have grown significantly over the decades add to the faux residential look. The landscaped property is fully enclosed by residential-style ornamental metal fencing.
Both of Canada’s major freight railway operators, CN and Canadian Pacific, are in the very early stages of determining the feasibility of using new zero-emission locomotives that are powered by batteries or hydrogen. This would reduce the ventilation requirements for such tunnels in their vast railway networks spanning North America, but the proven regular use of such zero-emission train technology could still be many years away.
Currently, the location of the south entrance of the tunnel in Brentwood Town Centre can be easily missed. But that could change from the future construction of a 627-ft-tall, 61-storey mixed-use condominium and hotel tower at 2211-2271 Rosser Avenue — immediately to the east of the tunnel’s south entrance. As one of Metro Vancouver’s tallest buildings, Amacon’s tower project would provide a landmark visual marker for the tunnel entrance in Brentwood, and it is being designed in a way to enable a potential future landscaped deck over the tunnel entrance.
Within Brentwood, the development impacts due to the Thornton Tunnel’s shallow depth in the area go up to at least the Staples building site; the City of Burnaby noted in the Buchanan West development master plan that the potential development concept for the easternmost end of the site — the Staples parcel at the northwest corner of the intersection of Lougheed Highway and Madison Avenue — is impacted by the tunnel running beneath.
Site of 2211-2271 Rosser Avenue, Burnaby. (Chris Dikeakos Architects/Amacon)
Artistic rendering of 2211-2271 Rosser Avenue, Burnaby. (Chris Dikeakos Architects/Amacon)
Artistic rendering of 2211-2271 Rosser Avenue, Burnaby. (Chris Dikeakos Architects/Amacon)
Artistic rendering of 2211-2271 Rosser Avenue, Burnaby. (Chris Dikeakos Architects/Amacon)
The next major project under the BIRP strategy is the $200-million new Holdom Avenue Overpass crossing above CN’s trunk railway within the southeast corner of the Brentwood Town Centre district, replacing the existing ground-level railway crossing of Douglas Road. Construction on the overpass with four vehicle lanes, protected bike lanes, and pedestrian pathways will begin in late 2024 for a completion and opening in 2027.
Currently, Metro Vancouver stands at a crossroads in its decision-making process regarding the North Shore’s first fixed-link transportation project across Burrard Inlet since the 1960s.
TransLink is in the process of planning a Bus Rapid Transit (BRT) service between the North Shore (Park Royal in West Vancouver) and SkyTrain Metrotown Station in Burnaby via the existing Ironworkers Memorial Bridge and a connection with SkyTrain Brentwood Town Centre. With BRT as an interim service, the public transit authority intends to study future permanent rail-based rapid transit solutions for implementation over the longer term.
A recent preliminary study commissioned by the District of North Vancouver found that a new SkyTrain line following this same BRT route — roughly 19.5 km with a total of 10 SkyTrain stations — could see a high ridership level of 120,000 daily boardings by 2050, with the fastest travel time of only about 23 minutes. Such a project could also be coordinated with a new replacement Ironworkers Memorial Bridge for both vehicles and rapid transit, given that the bridge will reach the end of its lifespan over the coming decades.