New Fraser Valley highway interchange will be BC’s first ‘diverging diamond’

The widening of Highway 1 will bring a brand new type of interchange to the Fraser Valley—and leave motorists briefly driving on the “wrong” side of the road.

A “diverging diamond” interchange under construction at 264th Street will be the first of its kind in British Columbia. A similar junction may be built at the junction of Highway 1 and Sumas Way/Highway 11 in Abbotsford.

The new form of highway interchange is intended to make left-turns easier and less dangerous. And although drivers may take some time to adjust to a twisting new traffic pattern that is, by design, not straight-forward, experts say that the complicated design is easier to navigate than one might think.

A highway diamond

In Langley, work is well underway to construct a new junction at 264th Street. Last week, a new off-ramp and traffic signal were opened to allow for construction of the new interchange. Both junctions are among the valley’s busiest and most-crash prone stretches of road. (You can read our 2022 story on the valley’s deadliest intersections here.)

Meanwhile, in Abbotsford, crews have begun to clear a massive area surrounding Abbotsford’s Highway 1/Sumas Way junction to lay the groundwork for the construction of a new interchange. Preliminary renderings released in 2023 suggested the junction would also be a diverging-diamond intersection, although a provincial spokesperson wrote in an email that the specifics design has not yet been confirmed. The project is still in the procurement phase, and the successful bidder could still pitch an alternative concept.

When the Langley interchange is constructed, it will be the first of diverging-diamond junction in British Columbia.

Diverging-diamond interchanges perform the same basic function as a standard intersection interchanges, allowing drivers to enter or exit the highway via on- and off-ramps.

But the diverging diamond comes with one major innovation. As the local road (i.e. 264 Street) crosses Highway 1, its lanes swerve across one another, leaving traffic briefly travelling on the left-side of the road. That enables those entering the highway to turn left onto an on-ramp without crossing traffic travelling in the opposite direction. At the end of the overpass (or underpass), the lanes then cross again to restore right-side driving. Two signal lights will allow the north-south lanes of traffic to cross one another.

The design is complicated to explain, and only fractionally less confusing to see in a diagram. But experts say they are intuitive for drivers. You can see an artist’s rendering of the 264th interchange below. Below that, you can see the initial sketch of the Sumas Way junction.

264th Interchange

Sumas Way Interchange (diagram from 2023)

As the diagrams indicate, even if Sumas Way also gets a diverging-diamond interchange, it’s likely to be a little different from that at 264th Street. The biggest difference is that, because of rail tracks that predate the highway, at Sumas Way, highway traffic would flow over the local north-south traffic. At 264th Street, meanwhile, the highway would run beneath a twin overpass carrying north-south traffic.

Beyond the stoplights to allow the lanes to cross over one another, the junctions may have other signals for pedestrians and cyclists, and for highway drivers entering into the flow of city traffic. The diagrams posted by the province are subject to change. The Current asked the province for the latest information and designs on the two junctions, but did not receive any new renderings or images.

The province says diverging diamond intersections improve traffic flow by reducing left-turn lanes (and signals) that create congestion on overpasses. It says the design also boosts safety and allows for safe walking and biking paths across the highway.

The first diverging diamond intersection in the United States opened in 2009, and led to a massive drop in the number of accidents. Since then, dozens more have been constructed across the country.

Canada’s first diverging diamond interchange opened in Calgary in 2017. Six years later, the City of Calgary said the number of serious collisions had plunged by 75%, while the total number of accidents had dropped by 38%.The city had suggested that the intersection would also dramatically reduce rush hour delays, but did not provide statistics on whether the intersection accomplished that goal in its 2023 press release.

The website of Washington State’s transportation department concedes that diagrams of diverging diamond intersections look complicated, but says navigating the junctions at ground level is “actually very intuitive.”

“There really isn't anything new to learn, and striping, signing, and signal displays are very effective in routing drivers through the interchange,” the site says. “The lanes funnel drivers where they need to go, and there is only one route to take through the traffic signals with well marked and easy to follow entry and exit points.”

The extras

The Fraser Valley will be built to accommodate unique local needs.

In addition to lengthening the on- and off-ramps—a much needed change—the 264th interchange will be accompanied by both a truck parking facility on the southwestern edge of the junction and a park-and-ride lot north of the highway. The park-and-ride facility will be located next to a bus exchange that will have its own on-ramp. (Drivers currently use the wide shoulders on the northern side of the Highway overpass as a makeshift carpool parking lot.)

The Sumas Way/Highway 11 interchange is likely to include a new pedestrian and cycling path that provides an easier connection between Delair Road in the northeast and King Road and the University of the Fraser Valley to the southwest.

Without its former cloverleaf design, the Sumas Way junction will need a westbound off-ramp that begins well before the present-day off-ramps. That, along with a new HOV lane, will require the realignment of King Road and Riverside Road junction. That work is now in progress and is expected to continue through the summer.

The province says construction on all highway work between 264 Street and Mt. Lehman Road, including the 264 Street interchange, is expected to be finished by 2028. Construction between Mt. Lehman Road and Highway 11, including the Sumas Way/Highway 11 interchange, is supposed to be done by 2031.