What's the earthquake collapse risk of the Vancouver viaducts?

What's the collapse risk of the downtown Vancouver viaducts in an earthquake?

Dunsmuir and Georgia viaducts. (Kenneth Chan/Daily Hive)

When the Vision Vancouver party-led makeup of Vancouver City Council approved the Northeast False Creek Plan in January 2018, the timeline for carrying out the area’s redevelopment pegged the demolition of the Dunsmuir and Georgia viaducts for 2019.

It promised to make space for the construction of thousands of homes for 12,000 people, including significant social housing, as well as a vibrant entertainment district with ample retail, restaurant, and entertainment uses, improved and expanded public parks and public spaces, a redesigned seawall and shoreline, and various new community and recreational spaces.

By early 2019, the Vancouver viaducts demolition timeline was pushed to a 2020 start at the earliest.

And then, of course, the pandemic happened.

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The City of Vancouver’s last project updates on the Northeast False Creek Plan’s progress were in 2022. In April of that year, City staff indicated the demolition of the viaducts could begin no earlier than 2027. That same year, the City’s approved multi-year capital plan through 2026 stated reinvestments to structurally improve the viaducts would be required by 2032 if demolition is not performed.

By 2032, the 1972-built viaducts will reach 60 years of age.

Both viaducts span about 1.2 km in length between Beatty Street to the west and Gore Avenue to the east, just south of Chinatown.

The Dunsmuir Viaduct has two vehicle lanes for westbound-only traffic and a more recent protected bike lane that occupies the previous third vehicle lane, while the Georgia Viaduct has three vehicle lanes for eastbound-only traffic. The segment of the Georgia Viaduct between Beatty Street and the off-ramp exit onto Main Street is part of TransLink’s regional Major Road Network.

Northeast False Creek and the Dunsmuir and Georgia viaducts. (Ted McGrath)

Dunsmuir Viaduct looking east from Beatty Street. (Kenneth Chan/Daily Hive)

Although the 1970s-built viaducts were built to a freeway standard for a segment of the previously envisioned east-west highway linking downtown Vancouver with Highway 1, the twin structures that exist today are, first and foremost, a safety replacement of the area’s dilapidated 1915-built viaduct, known as the Hart McHarg Bridge.

Century-plus old remnants of this demolished viaduct still remain in Chinatown at the southwest corner of the intersection of Main Street and East Georgia Street, next to the Murrin Substation. According to the Vancouver Heritage Foundation, the Hart McHarg Bridge was poorly built and “plagued by difficulties from the beginning,” with major issues including sagging sections, timber propping up, and concrete falling to the ground below.

The area’s previous and existing viaducts were built to provide a direct road bypass over Canadian Pacific’s vast Northeast False Creek railyard — the current footprint of Andy Livingstone Park and International Village — and to address the steep grade change of the downtown Vancouver peninsula’s escarpment near Beatty Street. With the arrival of Expo ’86, the accelerating disappearance of heavy industrial uses in False Creek, and the post-Expo residential development plan, the railyards disappeared.

Like the safety rationale for removing the 1915-built viaduct over five decades ago, with each passing year, the same types of concerns now appear to be growing for the current viaducts.

In an interview with Daily Hive Urbanized, Anthony El-Araj, a principal at Vancouver-based Glotman Simpson and a project manager with 20 years of structural design experience, says the viaducts question should be addressed sooner rather than later.

Glotman Simpson has been directly involved in optimizing the structural designs of some of Vancouver’s largest and most challenging building projects to date, including the West Building of the Vancouver Convention Centre, which sits on water over pylons for nearly half of the structure’s footprint, as well as the unconventionally designed towers of The Arc Vancouver, Vancouver House, and the upcoming Fifteen Fifteen (“Jenga tower”).

El-Araj says structures are now designed for optimal seismic performance based on three different earthquake frequencies — the probability of withstanding the magnitude of an earthquake happening once in 475 years, once in 975 years, and once in 2,475 years. The latest building code standards require all new buildings and structures to be designed for the exceptionally powerful once-in-2,475-year earthquake event.

Between 1970 and 1985, the building codes required seismic performance for once-in-100-year earthquakes. The previous once-in-475-year standard was in practice from 1985 to 2005, until the current once-in-2,475-year standard was adopted.

“All these new buildings and bridges you see around town are designed for what we call a maximum credible earthquake. They’re designed to not collapse under pretty high ground shaking,” he said.

Dunsmuir and Georgia viaducts. (Kenneth Chan/Daily Hive)

Dunsmuir and Georgia viaducts, and the SkyTrain Expo Line elevated guideway. (Kenneth Chan/Daily Hive)

Based on the findings of the detailed technical seismic performance reports previously commissioned by the City, El-Araj says the existing 1970s-built viaducts would not perform well for the lowest measurement — the relatively frequent earthquake of a once-in-475-year seismic event.

“The actual viaduct girders could fail, the piers could fail, and the soil around the footings could fail, as well as the footings, too,” said El-Araj.

The options to address the viaducts question are to demolish the structures, as the City intends to do, or the alternative strategies of upgrading the viaducts or building brand new replacement viaducts.

In 2015, when the planning process was underway, the City estimated that an upgrade of the viaducts would cost between $50 million and $65 million to prevent them from collapsing in a moderate earthquake, which is a once-in-475-year scenario. Following such an earthquake, the viaducts would likely not be usable and may need to be replaced.

El-Araj believes that the original 2015 cost figure for proceeding with an upgrade is now double, north of $100 million, due to even greater seismic provisions in the building codes — which now require greater performance for heavier loading or higher ground shaking compared to the codes a decade ago — as well as inflating costs for construction materials and labour.

dunsmuir georgia viaduct skateboard skate plaza

Vancouver Skate Plaza underneath the Dunsmuir and Georgia Viaduct. (Kenneth Chan/Daily Hive)

Dunsmuir and Georgia viaducts. (Kenneth Chan/Daily Hive)

Rehabilitating the viaducts would include adding piles to the foundation footings, improving the structural columns (piers), and upgrading the bridge decks with steel wrapping.

“It’s pretty extensive work to get it up to that frequent earthquake capacity for collapse prevention,” said El-Araj.

He estimates the option of an upgrade would provide roughly 70% of the seismic capacity of a brand-new replacement structure following the latest standards, which would likely carry a higher cost.

Even in 2018, the City’s updated estimated costs pegged an upgrade of the viaducts at $90 million, which would extend the structures’ lifespan by another 50 years. Brand new replacement viaduct structures would cost about $120 million, which would provide a lifespan of 100 years.

The last major road viaduct bypass crossing built in the Metro Vancouver region is the 2010-built Coast Meridian Overpass, which is a four-lane arterial road over Canadian Pacific’s expansive railyard in Port Coquitlam.

The Coast Meridian Overpass is 750 metres long, including a 580-metre-long cable-stayed bridge for the main span directly above the railyard, and it cost $132 million ($187 million in 2024 dollars) to build, with construction starting in March 2008 and ending in March 2010.

coast meridian overpass port coquitlam construction 1

2009 construction progress on the new Coast Meridian Overpass above the Canadian Pacific railway in Port Coquitlam. (Collings Johnston)

Road deck of the Coast Meridian Overpass above the Canadian Pacific railway in Port Coquitlam. (Google Maps)

El-Araj does not believe it makes sense to upgrade the Dunsmuir and Georgia viaducts simply to get their seismic performance to meet below-current standards.

The City’s selected option of demolishing the viaducts was estimated to cost about $200 million in 2015, including the major costs associated with building a replacement ground-level road network.

By the time Northeast False Creek Plan was approved in January 2018, the combined cost of viaducts demolition and the construction of new replacement surface road network grew to $360 million, with about 80% going towards engineering-related costs such as the demolition of the structures and the construction of new streets, utilities, and other structures, and the remaining 20% related to environmental remediation, non-City-owned utilities, and some of the area’s new park-related expenses — all before accounting for the contingency fund.

Out of the $360 million, the City’s 2018 updated estimates pegged the removal of the viaducts and the construction of the new structures at $96 million, the new realigned route of Pacific Boulevard and Expo Boulevard within the area at $59 million, the relocation of City-owned utilities at $21 million, and traffic detours throughout the entire demolition and construction period at $7 million.

Another $48 million of the $360 million total would go towards the temporary skateboard park ($3 million) due to the demolition of the Vancouver Skate Plaza beneath the viaducts at Quebec Street, environmental remediation ($21 million), and new non-City utilities ($24 million).

The $360 million estimated cost also consists of $85 million for a contingency fund and construction allowance for any unexpected costs, and $44 million for further project planning, studies, and public consultation expenses.

Existing condition:

Existing condition of Northeast False Creek. (Google Maps)

Potential future condition:

Previous 2018 rezoning concept for Concord Pacific’s redevelopment in Northeast False Creek. (Concord Pacific/Dialog/Civitas Studio)

In early 2019, City staff leading the Northeast False Creek Plan’s execution told Daily Hive Urbanized almost all of the new replacement ground-level road network needs to be in place before the viaducts can be fully demolished — an important measure to maintain the area’s significant regional arterial traffic flow.

This includes overhauling Pacific Boulevard from its current one-way configuration into a wider two-way, six-lane road between Quebec Street and the Cambie Street Bridge. It would then be followed by the construction of a new ramp-like short road viaduct in the area between BC Place Stadium and Rogers Arena — a two-way, four-lane road that extends West Georgia Street between Beatty Street and the altered Pacific Boulevard, within an area currently occupied by Griffiths Way and the western end of the Georgia Viaduct.

Conducted in stages, most of the ramp would be built, and then the westernmost section of the Georgia Viaduct would be demolished. At that point, work would be performed as quickly as possible to finish the remaining segment of the ramp to connect with Beatty Street. The ramp is expected to be one of the most expensive components of the new replacement surface road network.

After the ramp is fully opened to vehicles, demolition work on the remaining portions of the viaducts will be in full swing, which is expected to take about three years.

Existing condition:

Existing condition of the westernmost end of the Georgia Viaduct at Beatty Street, between Rogers Arena and BC Place Stadium. (Google Maps)

Potential future condition:

georgia-street-ramp-vancouver-viaducts-2

Preliminary conceptual artistic rendering of the two-way, four-lane West Georgia Street extension ramp from Beatty Street to Pacific Boulevard — between BC Place Stadium and Rogers Arena. (City of Vancouver)

City staff at the time also noted that a surgical demolition approach would be necessary for the segments of both the Dunsmuir and Georgia viaducts next to BC Place Stadium, Rogers Arena, and various residential towers. This could involve cutting sections of viaducts and using cranes to lift smaller chunks of the structure out of the area to avoid contact with the buildings.

El-Araj suggests that in addition to the potential structural failure of the viaducts during a moderate-magnitude earthquake, there is also a risk that the falling viaducts could severely damage the adjacent structures.

Various Concord Pacific and Henderson Development condominium towers, Rogers Arena, and Aquillini Developments’ rental housing and office towers, which are part of the overall Rogers Arena complex, are immediately adjacent to the viaducts.

SkyTrain Expo Line’s elevated guideway also runs parallel to the viaducts in the area — and it even dives under the viaducts. This segment of the Expo Line is by far the busiest section of the region’s entire SkyTrain network.

“There’s certainly the possibility that those viaducts could collapse into a building, and those buildings definitely aren’t designed to take the collapse of an adjacent structure. I could see hesitancy from developers and purchasers to build and buy homes adjacent to what could arguably be classified as a dangerous structure,” said El-Araj.

Georgia Viaduct between Rogers Arena and a rental housing tower. (Kenneth Chan/Daily Hive)

Rogers Arena’s main plaza underneath the Dunsmuir Viaduct. (Kenneth Chan/Daily Hive)

Rogers Arena’s main plaza underneath the Dunsmuir Viaduct. (Kenneth Chan/Daily Hive)

Rogers Arena entrances next to the Georgia Viaduct. (Kenneth Chan/Daily Hive)

Rogers Arena entrances next to the Georgia Viaduct. (Kenneth Chan/Daily Hive)

Costco and condominium towers next to the Dunsmuir Viaduct. (Kenneth Chan/Daily Hive)

SkyTrain Expo Line’s elevated guideway underneath the Dunsmuir and Georgia viaducts. (Kenneth Chan/Daily Hive)

The magnitude 6.9 earthquake that struck San Francisco’s Bay Area in 2001 led to the collapse of much of the 1957-built, three-km-long double-decked highway viaduct, known as the Cypress Street Viaduct. The viaduct collapse also severely impacted adjacent structures. Deaths due to the viaduct collapse accounted for most of the 63 deaths recorded in the earthquake.

“We don’t have a good appreciation for earthquakes here because we don’t see them that often. In California, they get frequent earthquakes, so the public generally has a better appreciation for it,” he continued.

Upon inquiry, Concord Pacific told Daily Hive Urbanized that their plans to redevelop their large waterfront property just south of the viaducts are in progress. The demolition of the viaducts is one of the major factors in determining when they can proceed with the project.

“The timeline for development depends not only on viaduct removal but also on planning cooperation, financing and market conditions. We can’t speak for all the other four Northeast False Creek land owners, but we are ready to move ahead,” Matt Meehan, the senior vice-president of planning for Concord Pacific, told Daily Hive Urbanized.

“With the other bridges having been recently seismically upgraded, we understand there is urgency in the demolition of the viaducts, as well as in planning for the area.”

Meehan adds that his team is “excited” to work with the City’s new chief planner on their rezoning, adding that “with the removal of the viaducts, we are excited to plan and build our last remaining lands in Northeast False Creek alongside the four other landowners.”

concord pacific lands northeast false creek concept

Conceptual artistic rendering of the Concord Pacific Place development in Northeast False Creek. (Concord Pacific/Civitas Studio)

Altogether, the entire public benefits package of Northeast False Creek Plan was pegged at $1.7 billion based on 2018 estimates, with the expectation that this would be largely achieved through cash and in-kind CACs and other types of contributions from developers through the area’s rezonings. This includes the aforementioned $360 million related to the viaducts demolition and new roads.

In 2023, City staff indicated that a $110 million cash contribution from Concord Pacific — related to affordable housing sites elsewhere in the False Creek area — is intended to be directed towards covering the costs of demolishing the viaducts and building the new replacement surface road network. This figure does not entail the additional public benefits contribution that will be determined by the future rezoning of their development site next to Creekside Park.

The area’s other major landowner is Canadian Metropolitan Properties Corporation (CMPC), which owns the Plaza of Nations site just west of Concord’s site.

The rezoning application for the Plaza of Nations redevelopment was approved in July 2018 as one of the last major decisions by the Vision Vancouver-led City Council. In exchange for the high-density market development uses Canadian Metropolitan Properties has promised the City a total community amenities contribution (CACs) package of $325 million, including $225 million in on-site in-kind CACs — such as social housing, a community centre with an ice rink, a childcare facility, and extensive public spaces, including a revamped seawall — and $100 million as a cash contribution directly to the municipal government.

Under the rezoning agreement, City staff previously noted the Plaza of Nations’ cash CACs would be prioritized towards covering the costs associated with viaduct demolition and the new replacement surface road network. The first $20 million cash CACs payment was due before the enactment of the rezoning bylaw, another $20 million was due for the first development permit issuance of the multi-phased redevelopment, and the remaining $60 million is based on the percentage of development floor area approved in each building permit.

In June 2022, the City’s Development Permit Board approved the development permit application for the first phase of the Plaza of Nations redevelopment — situated on the west side of the development site, replacing a surface vehicle parking lot. This initial tower contains 1.008 million sq ft of total building floor area, making it one of Vancouver’s largest mixed-use buildings in terms of floor area. However, City records show the project has yet to reach the building permit stage.

In an email to Daily Hive Urbanized, Daisen Gee-Wing, a senior vice-president of Canadian Metropolitan Properties, says there was a recent change in the makeup of shareholders and the percentage amongst them, but CMPC still owns the Plaza of Nations site.

Another area landowner is Pavco, the provincial Crown corporation that owns and operates BC Place Stadium. In July 2018, Pavco received rezoning approval for its proposal to build a mixed-use residential tower next to the southeast corner of the stadium — a small site at the northwest corner of the future intersection of Pacific Boulevard and the new West Georgia Street ramp.

But Pavco’s tower project has stalled. At the time of the rezoning approval, City Council stipulated that if Pavco were to pursue the taller tower option, it would need to incorporate rental housing into the project, with Pavco officials expressing some uncertainty over the financial viability of such a housing tenure. The market development is intended to help fund the cost of the stadium’s previous renovations and operating costs.

No CACs are required for the Pavco project; if the tower were to advance, the project would not generate any cash CACs to cover any of the City’s expenses towards demolishing the viaducts and building the new replacement surface road network. Due to a previous agreement, the provincial government’s BC Place Stadium renovations, concluding in 2011, were deemed to be a significant community amenity, and Pavco is also providing the land needed for the statutory right-of-way for building the new West Georgia Street ramp.

In December 2023, Pavco announced a new revenue-generating strategy to significantly overhaul and expand its outdoor advertising video screen systems, including a full replacement of the existing freestanding digital board structure at its tower development site. This work is expected to reach completion later in 2024.

2020 model of the Plaza of Nations redevelopment. (James Cheng Architects/Canadian Metropolitan Properties)

2020 artistic rendering of the Plaza of Nations redevelopment. (James Cheng Architects/Canadian Metropolitan Properties)

Artistic rendering of Pavco’s early conceptual design for a tower at Site 10C at the southeast corner of BC Place Stadium. (Pavco/Stantec Architecture)

Artistic rendering of Pavco’s early conceptual design for a tower at Site 10C at the southeast corner of BC Place Stadium. (Pavco/Stantec Architecture)

When City Council approved the Northeast False Creek Plan in 2018, the Vancouver viaduct demolition and surface vehicle road implementation plan had an almost identical start and completion timeline to the project to demolish the Alaskan Way Viaduct in downtown Seattle and construct new waterfront roads and public spaces.

Demolition of the Vancouver and Seattle viaducts was both originally scheduled to begin in 2019, with only the latter project starting on time in 2019. A key difference is that downtown Seattle’s road network project is largely led by the Washington State Department of Transportation — a much heavier weight than the municipal government, with the City of Seattle leading the comparatively smaller component of the new surface roadways and waterfront public spaces.

Demolition of the 3.5-km-long, double-decked Alaskan Way Viaduct — part of the State Route 99 freeway — began in February 2019, just days after the state government opened a new replacement four-lane underground highway built using the tunnel boring machine method. The viaduct demolition process reached completion in November 2019.

Work on the new surface road segments of Alaskan Way and Elliott Way began immediately after the viaduct removal, and the first new surface vehicle lanes opened in late 2020.

In 2025, after a one-year delay due to the pandemic, the entire “Waterfront Seattle” precinct on the former footprint of the viaduct will reach completion, including the roads, promenades, landscaped areas, plazas, walking and cycling paths, piers, and public park spaces. This area is expected to be the site of Seattle’s official 2026 FIFA World Cup Fan Festival.

After the magnitude 6.8 earthquake that hit the Seattle area in 2001, the 1953-built Alaskan Way Viaduct sustained some damage that weakened the structure’s integrity to the extent that it necessitated interim emergency repairs. This triggered a concerning pattern of settlement. There was a high probability that another moderately powerful earthquake could cause a structural collapse of the viaduct, similar to the Bay Area’s freeway collapse.

Addressing the safety issues of the viaduct became a priority, and by 2009 an agreement was reached between multiple levels of government to proceed with a multi-billion dollar plan to build the new bored highway tunnel, demolish the viaduct, and create new surface roads and public spaces.

Demolition work on the Alaskan Way Viaduct in downtown Seattle in April 2019. (Washington State Department of Transportation)

October 2023 construction progress on downtown Seattle’s new waterfront on the former footprint of the Alaskan Way Viaduct. (Kenneth Chan/Daily Hive)

Artistic rendering of Waterfront Seattle. (City of Seattle)

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