Abstract Manager

The Trans Canada Highway (Highway 1) connects Metro Vancouver to the North Shore, the Horseshoe Bay ferry terminal and Highway 99. It is a vital local, regional, and provincial corridor for people, services, and goods. Traffic on Highway 1 in North Vancouver has steadily increased in the past decade and the aging Iron Workers Memorial Bridge (IWMB) and the adjacent three Lower Lynn Interchanges, designed and built over 50 years ago, could no longer accommodate the increased traffic along the highway. This congestion affected all aspects of life on the North Shore, including commuting, regional and local trips, industrial and commercial operations, transit service, and developments.  The BC Ministry of Transportation and Infrastructure (BCMOTI) commissioned the Lower Lynn Improvements Project to upgrade the three Lower Lynn Interchanges to address safety and mobility for all modes of travel.  The IWMB is the primary capacity constraint, but it will not be upgraded in the foreseeable future.  Since additional “downstream” capacity improvements were not possible, the project focuses on innovation, multi-modal accommodation, and stakeholder engagement to maximize capacity to all users despite the limited capacity of the IWMB.  This presentation will focus on the design innovation of the Main Street/Dollarton Highway Interchange, the most heavily used of the three interchanges, through the introduction of an adaptive ramp signal.

Located at the north abutment of the IWMB, besides the typical mix of urban traffic, the Main Street/Dollarton Interchange carries significant heavy truck traffic due to the proximity of Port and industrial areas. There is also a major transit exchange (Phibbs Exchange) in the northwest quadrant of the interchange. The previous direct taper on-ramp from Dollarton Highway eastbound to Highway 1 southbound, was very short and provided no acceleration lane, and was a major point of congestion and crashes along the highway. Buses leaving Phibbs Exchange also used this on-ramp, which significantly impeded transit service across the IWMB.  The Main Street/Dollarton Highway Interchange upgrade combined this short on-ramp with the Main Street eastbound on-ramp to Highway 1,  providing the required acceleration and merge distance onto the IWMB’s southbound auxiliary lane. Due to geometric constraints, the combined Main Street and Dollarton Highway on-ramps had to be metered by a ramp signal system. Testing this ramp signal system involved an extensive and iterative microsimulation analysis, research, ongoing stakeholder discussion and a balanced approach to address all users of this interchange. The interchange opened in October 2021.