Anyone who has driven around Metro Vancouver recently will know that traffic congestion has become a major regional issue and, as in urban centres elsewhere, this congestion is the combined effect of rapidly rising population and ageing infrastructure. Here though, the situation is further complicated by the complex river system of the Lower Mainland, including the main Fraser River, the Fraser’s north and south arms, the Burrard Inlet and the Pitt River, all of which necessitate multiple bridge crossings to connect the region’s communities.
|Today’s Port Mann Bridge has the highest traffic volumes per lane among all major water crossings in Vancouver and is congested for about 13 hours a day.
|The north tower of the new Port Mann
Bridge under construction. The marine trestle (right foreground) is
providing construction access to the North Tower and will be removed
once the bridge is completed. The north tower was recently the scene of
two concrete pours requiring 4,550 cu. m in the first lift and 3,396
cu. m for the second lift, for a total of 7,946 cu. m. At one stage,
there were 52 trucks and three pumps involved. Due to space constraints
on the trestle, a barge was brought in to provide a working platform
for the third pump.
Port Mann/Highway 1 Improvement (PMH1) Project is part of the B.C.
Ministry of Transportation and Infrastructure’s Gateway Program, made
up of three major infrastructure projects to improve roads and bridges
throughout Metro Vancouver; The Port Mann/Highway 1 Improvement (PMH1)
Project; The South Fraser Perimeter Road Project and The North Fraser
Perimeter Road Project. The Pitt River Bridge and Mary Hill Interchange
is a stand-alone component of the North Fraser Perimeter Road Project.
|With an overall width of 65 m, the new 10-lane, cable-stayed bridge will be the widest in Canada.
the Cape Horn Interchange, a relocated 1.8 m diameter storm sewer is
being placed on concrete saddle sections that are in turn supported on
piles driven into glacial till due to very soft clay and silt ground
|The Cape Horn interchange was originally built in the 1960s and serves four major routes.
completed, the extensively redesigned Cape Horn interchange will have
16 structures to help provide direct connections between Highway 1 and
major arterial roads.
|Demolition of the existing Canadian Pacific rail overpass at the Cape Horn Interchange.
Today’s Port Mann Bridge has the highest traffic volumes per lane among all major water crossings in Vancouver, carrying approximately 127,000 vehicles per day. The original four-lane bridge (now five lanes) was built in 1964 when the population of Greater Vancouver was 800,000. With a current population of more than 2.1 million, the bridge is congested for around 13 hours a day.
Its replacement, the distinctive new Port Mann toll bridge, scores a number of Canadian firsts, says Stephen N. Docherty, bridge section manager for the Transportation Investment Corporation (TI Corp).
With an overall width of 65 m, the 10-lane, cable-stayed bridge will be the widest in Canada, including its two five-lane roadways, a 5 m wide sidewalk with 3.5 m of usable space for pedestrians and cyclists, as well as a 10 m wide median.
The river crossing consists of three spans: 190 m, 470 m and 190 m, for a total length of 850 m, with the two separate bridge deck structures suspended from a single north pylon (tower) and single south pylon located between the decks on the single north and south piers respectively. Some 288 cables will provide the support to the bridge decks. The two towers will rise about 110 metres above the bridge deck, providing some 40 m of navigation clearance.
The new Port Mann Bridge accounts for just under half of the overall project cost of $2.46 billion. Either side of the 850 m long cable stayed bridge are the 820 m long north approach and 360 m south approach. The bridge foundations include steel piles driven into till (glacial sediments). The north tower is founded on 63 steel piles of 1.8 m diameter, each 70 m long, for a total pile length of 4,400 m. The south tower has 50 steel piles, 1.8 m diameter and 80 m long for a total pile length of 4000 m.
The north approach will be constructed from segmental precast concrete box sections, with a total of 80,000 cu. m of concrete including the substructure. The foundations on the land section of the north approach include 78 drilled shafts, each 2.5 m in diameter and about 50 m long, while the foundations of the river section of the north approach include 66 driven steel piles, each 1.8 m in diameter.
The south approach also consist of segmental precast concrete box section, with a total here of 50,000 cu. m of concrete, including the substructure. The south approach foundations consist mainly of driven steel piles, with 82 piles each 1.8 m in diameter and about 70 m long and 30 drilled shafts each 1.8 m in diameter and about 40 m long.
Cape Horn Interchange
The existing Cape Horn interchange was originally built in the 1960s and serves four major routes; Highway 1, Lougheed Highway, Mary Hill Bypass and United Boulevard. Despite a history of site-specific improvements to meet increasing volumes and changing traffic patterns, this interchange has already reached its design limits and current estimates suggest that traffic volumes at Cape Horn will increase nearly 30 per cent by 2031, fuelled by increasing traffic to a growing commercial area on United Boulevard in addition to increasing through traffic. The intersection has only four structures, resulting in several at grade intersections, tight geometry and awkward ramp design.
When completed, the extensively redesigned interchange will have 16 structures to help provide direct connections between Highway 1 and major arterial roads.
Don Jacobsen, senior project engineer for Kiewit/Flatiron General Partnership, explains that very soft clay and silt ground conditions have certainly posed challenges for the project. At the Cape Horn Interchange, for instance, a relocated 1.8 m diameter storm sewer is being placed on concrete saddle sections that are in turn supported on piles driven into glacial till.
At several other locations in the interchange construction zone, the roadway widening and new ramps have already been preloaded with fill to minimize future settlement. Still within the interchange footprint, Agra Foundations Limited was in action installing some 2,500 stone columns to depths of 22 m for new bridge abutments, another technique used here to
improve poor ground conditions and prevent soil liquefaction during an earthquake.
Ground conditions are not the only things keeping project staff busy. Traffic management is also an important part of the project and extensive use is being made of the Internet to provide frequent construction updates to the travelling public. These bulletins detail changes such as traffic pattern shifts and temporary lane closures, as well as details of upcoming construction.
Pamela Ryan, communications counsel for the Port Mann/Highway 1 Project, explains that, since construction entails extensive improvements to existing infrastructure in a large and growing urban area along the primary goods movement and commuting route, a key goal of the project is to minimize disruption and maximize predictability for area residents and businesses as well as current road users.
During the comprehensive community consultation program undertaken to develop pre-designs, the project team consulted with over 4,500 people through numerous open houses and stakeholder meetings in municipalities throughout Metro Vancouver, and the project received broad-based public support. Detailed design consultation, now underway, is focusing on long-term noise mitigation measures, landscaping and access at the local community level as conceptual designs are refined and construction continues along the 37 km project corridor.
For area residents overlooking the Cape Horn interchange, for example, considerable work has been done to mitigate any noise concerns. At a local area consultation meeting held at the end of January, attendees were given a discussion guide that described proposed noise reduction measures and even detailed noise wall finish and landscaping options. Residents were also invited to express their preference for a no-noise wall option that would maintain current lower level viewpoints, but with the risk of increasing traffic-related noise as future traffic volumes rise.
|Port Mann project delivery and timing
The Port Mann Bridge / Highway 1 project is being delivered by the Transportation Investment Corporation (TI Corp.) with Kiewit/Flatiron General Partnership as the design-build contractor. TI Corp is a new provincial Crown corporation established in 2008 to implement the PMH1 Project. Construction of the PMH1 improvements has been divided into four segments: Vancouver – Burnaby (15 km); Coquitlam – Cape Horn (4 km); the new Port Mann Bridge (2 km) and removal of the existing bridge; Surrey – Langley (16 km).
PMH1 Project construction began in August 2008 and is expected to be complete by December 2013, with the new bridge operational by December 2012. Once the new bridge is built, the existing five-lane crossing will be removed. The new bridge will have three through-lanes in each direction and two local-connection lanes in each direction dedicated for local access to and from Surrey and Coquitlam.
The project also includes congestion-reduction measures such as HOV lanes, transit and commercial vehicle priority measures, improvements to the cycling network and an electronic toll on the bridge. The new bridge is being built to accommodate future light rail transit while the project will also provide for a Highway 1 RapidBus service between Langley and Burnaby.