Moving after the shaking

From the planning assumptions in the province’s Earthquake Immediate Response Strategy:

From the province’s risk and resilience assessment, on its Cascadia scenario:

Two provincial documents, written for two different scenarios, give the same instruction. The plan assumes people will not drive out, and that the roads will be doing other work.

Large parts of the area “will be inaccessible by road due to earthquake-induced landslides, liquefaction, and other secondary impacts such as bridge collapses”. And “Road, rail, air, and marine transportation will be disrupted, and existing supply chains will be inoperable.” [1] Liquefaction there means saturated soil losing its strength and behaving like a liquid while the ground shakes.

What happens to those crossings in a major earthquake, and to the ground their approaches sit on, is the subject of transportation.

The signs stand on roads across the region. A network of provincial and municipal roads was designated in 1995 across Metro Vancouver and Greater Victoria to move emergency responders and supplies. [3] The routes are open to everyone until a state of emergency is declared, and then they are activated and controlled. Authorised users must carry both government-issued photo identification and employment identification. [4]

The official instruction to the public is to get off the route as soon as possible, to make way for emergency responders. [4]

The province does not oversell them: “Like any infrastructure, these routes are susceptible to hazards and could potentially be negatively impacted by the emergency event.” [3]

The doctrine changed in June 2018: “DRRs are not designated pre-event. DRRs are determined at the time of the event based on the needs of response and recovery and available options.” What is designated in advance is now called a critical route. [5] The advice to the public is unchanged.

Among the published considerations for choosing roads for response routes: “Consider avoiding steep grades, circuitous routing, bridges, tunnels, overpasses and underpasses.” [6] Seismic retrofit status is one of the vulnerability criteria in the same guide, alongside soil stability and how close the road runs to gas and water lines. [6]

Metro Vancouver’s regional debris management plan sets the clearing priority:

Local roads are last. The plan’s suggested starting point is one this region already knows from winter: “Local Authorities may choose to use their snow removal routes as a base”. [7]

Provincially, the same sequencing applies to reopening. Critical routes “are used as a reference to prioritize the restoration of routes for regional mobility for all traffic”, and “Emergency responders should only use damaged routes after safety assessments have deemed the damaged routes safe for emergency use.” [5]

The only measured evidence of how long it takes to reopen a severed highway in this province comes from the atmospheric river of November 2021. Every figure below is rainfall damage from that storm. None of it was caused by an earthquake.

• Highway 5, the Coquihalla. Closed on 14 November 2021 by that rainfall, with more than 20 damaged sites along 130 km, including seven bridges where spans collapsed or were heavily damaged. Reopened to commercial traffic in 35 days and to all traffic after about 66 days. The last permanent bridge was finished in October 2023, about 23 months after the storm. [9]
• Highway 1, the Fraser Canyon. Closed on 14 November 2021 by the same rainfall, with 18 damaged sites between Hope and Spences Bridge, and reopened after 61 and 71 days on two segments. Permanent repairs on that rainfall damage ran into 2025, with one culvert expected in 2026. [10]
• Highway 8, the Nicola Valley. Also closed by the November 2021 rainfall, with 25 damaged sites and more than 13 km of road to rebuild. Reopened to the public on 9 November 2022, about 12 months after the storm, and restored to two lanes only in December 2025. [11]

The provincial flood strategy puts the economic impact of the November 2021 rainfall at $5 to $7 billion and records that it cut “main access routes to B.C. and Canada”. [12] Peer-reviewed work on the same rainfall event describes its ground failures as “severing land connectivity between Metro Vancouver and the rest of Canada”, and one of its authors works for the road authority. [13]

Those are the durations this road authority and these contractors achieved in this terrain.

Federal mapping “concluded that none of the landslides that entered Howe Sound were large enough to produce a significant tsunami”, and a landslide into the sound large enough to produce damaging waves on Bowen Island is assessed as unlikely. [14] An earlier North Shore assessment agrees, putting the probability as “very low, although not zero” and finding the North and West Vancouver waterfronts not at risk from such a wave. [15]

The route out of the region would be a damaged road, cleared in an order that puts local streets last. [7] How much of the network the province expects to be working, and for how long, is set out in transportation.