A look at the immersed tube concept for the new Massey Tunnel (RENDERINGS)

Oct 8 2019, 8:12 pm

Pivoting from the previous $3.5-billion, 10-lane suspension bridge concept, a task force of Metro Vancouver mayors and other regional leaders last week selected the option of an immersed-tube tunnel replacement for the ageing George Massey Tunnel.

The task force chose a modernized version of the construction methods used to build the existing 1959-built, four-lane tunnel for the new eight-lane replacement.

The rejected options were a deep-bore tunnel and a long-span suspension bridge; almost immediately, the deep-bore tunnel option was dismissed over its potential cost of three times more than each of the other two options, long construction timeline, high construction risks, significant farmland footprint impacts, and the need to retain, retrofit, and maintain the existing tunnel for pedestrians and cyclists.

Highly preliminary conceptual artistic renderings for depiction purposes, created by the provincial government for the task force’s consideration, provide a first glimpse of what the potential alignment of the new immersed-tube tunnel and tunnel portals could look like. These visualized concepts are far from the final design, which will be created following detailed planning and engineering work, if this option is ultimately selected by the provincial government.

George Massey Tunnel

Highly preliminary conceptual artistic rendering of an immersed-tube tunnel replacement for the George Massey Tunnel. (Government of BC)

George Massey Tunnel

Highly preliminary conceptual artistic rendering of an immersed-tube tunnel replacement for the George Massey Tunnel. (Government of BC)

The bed of the Fraser River, on a footprint next to the existing tunnel, would be trenched to hold a pre-fabricated tunnel structure dropped in by barges. The tube would then be covered to protect the structure.

Both sides of the river also require excavation, and ground densification for seismic resiliency would be required for the full length of the tunnel.

It is anticipated construction can only occur during a six-month window each year, requiring two or more construction seasons. Deas Island Regional Park on the Delta side would be temporarily separated for the excavation required for the southern tunnel portal, which leads to a new bridge between Deas Island and Delta.

George Massey Tunnel

Highly preliminary conceptual cross-section of an immersed-tube tunnel replacement for the George Massey Tunnel. (Government of BC)

George Massey Tunnel

Highly preliminary conceptual alignment of the immersed-tube tunnel replacement for the George Massey Tunnel. (Government of BC)

The task force, comprised of regional mayors of cities directly affected by the crossing, as well as First Nations and TransLink representatives, was formed shortly after the provincial government released its independent study findings last year that determined 10 lanes was too much capacity. At the time, the provincial government said it would seriously consider the input of local governments in determining a new direction.

In a statement to Daily Hive, Claire Trevena, the BC Minister of Transportation and Infrastructure, maintains a new approach on the crossing replacement is necessary. She asserts the previous bridge project under the governance of the BC Liberals lacked consultation, resulting in opposition, and had “unfair tolls.”

“The Ministry is pleased the Metro Vancouver Task Force was able to come to agreement on the option they want to see for the crossing. We are continuing to talk with affected stakeholders and public information sessions are planned for later this year,” she said.

“This time, through collaboration, we have developed shared principles, goals and objectives for a new crossing that will meet the needs of people who live and work in this region.”

immersed tube tunnel

Artistic rendering of a section of pre-fabricated immersed-tube tunnel construction in Denmark. (Femern A/S)

Trevena emphasizes that any option for approval will be “subject to formal and rigorous environmental review which includes additional and very focussed consultation.” Although the immersed-tube tunnel option has the greatest impact due to in-river construction, she says it has the lowest long-term impact and the greatest potential for environmental enhancements.

With the task force’s chosen eight-lane crossing, six lanes will be purposed for general traffic while two lanes will be dedicated to public transit.

“It will improve traffic flow, manage congestion and will be designed to encourage transit ridership. Getting people out of their cars by improving transit is a priority for the region and the Province,” Trevena added.

george massey bridge

Artistic rendering of the cancelled 10-lane bridge project to replace the George Massey Tunnel. (Government of BC)

When asked to comment today on the task force’s selected option for the replacement project, TransLink CEO Kevin Desmond said the cancelled 10-lane bridge plan also “had excellent transit supporting features and connections.”

“My understanding is that the eight-lane tunnel will have the same kind of really good transit connections. That is what we’re most focused on,” said Desmond.

“We want to make sure that whatever is built means that we can provide excellent transit connections for the people in the southern areas of the region. Whether it is going to be high-capacity bus or rail, let’s build something that supports the next 50 years.”

Trevena says the provincial government will make its final decision based on feedback from the regional district and others in an upcoming engagement process. A new business case process will fully identify the costs and benefits of the options.

There is no definitive timeline for the project’s implementation, but the Ministry previously indicated a possible 2030 completion. The region’s mayors want the project expedited, with a completion in 2025 or 2026.

George Massey Tunnel

Portal into the existing George Massey Tunnel. (Government of BC)

The provincial government is also funding and overseeing the Pattullo Bridge replacement project, after taking the responsibility and burden of delivering the new bridge away from TransLink. The $1.4-billion project is currently in its procurement phase, with construction expected to begin by the end of this year for an opening in 2023.

The new Pattullo Bridge will feature four travel lanes and associated walking and cycling infrastructure. The bridge deck can be widened in the future to accommodate six travel lanes.

On an average day, the George Massey Tunnel sees about 80,000 vehicles, while the Pattullo Bridge sees 68,000 vehicles.

8-lane, deep-bore tunnel concept

George Massey Tunnel

Highly preliminary conceptual artistic rendering of a deep-bore tunnel replacement for the George Massey Tunnel. Large and deep tunnel boring machine pits are also required at both ends of the tunnel. (Government of BC)

George Massey Tunnel

Highly preliminary conceptual artistic rendering of a deep-bore tunnel replacement for the George Massey Tunnel. (Government of BC)

George Massey Tunnel

Highly preliminary conceptual artistic rendering of a deep-bore tunnel replacement for the George Massey Tunnel. (Government of BC)

8-lane, long-span bridge concept

George Massey Tunnel

Highly preliminary conceptual artistic rendering of an eight-lane bridge replacement for the George Massey Tunnel. (Government of BC)

George Massey Tunnel

Highly preliminary conceptual alignment of an eight-lane bridge replacement for the George Massey Tunnel. (Government of BC)