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Background: The Davenport Diamond Grade Separation

Davenport Diamond construction map

The Davenport Diamond is one of the last high-traffic rail crossings in Toronto. To enhance safety and reliability, and to allow the significant expansion and enhancement of rail service promised by Metrolinx, the Davenport Diamond level crossing will be removed by constructing an overpass to separate the freight corridor from the GO corridor.

The Overpass

Train going under overpass

For trains to be able to pass over the CP tracks, a 570 metre bridge would be needed, with berms located at either end. The berm along Erwin Krickhahn Park will be naturalized. The Guideway would be constructed in an existing residential and mixed-use-neighbourhood, with most of the visual and construction impacts in the middle section where the Guideway is elevated. The main design challenge is to physically and visually lighten the bridge structure, and to design the space beneath the bridge to be safe and beautiful. The design has maximized the extent of the berms at either end to shorten the length of the bridge to reduce the visual impact of the structure.

Cross-section of proposed guideway

The bridge would extend 570 metres between Wallace Avenue and just south of Davenport Road, bookended to the north and south by sloping, bermed green walls or vertical retaining walls. 

Lightening the Bridge

The primary goal of the Guideway structural design is to lighten its mass and visual impact. The length of the approach berms at either end have been maximized, so that the length of the elevated Guideway is 570 metres from the previous 847 metres – a reduction of a third. The depth of the Guideway is minimized by using twinned, round columns every 16 metres. This design is very different than a typical raised highway overpass such as the Gardiner Expressway, which is much larger, and sits on pre-cast I-shaped beams sitting on concrete beams and columns, which can create an unwelcoming, graffiti-prone environment with poor lighting beneath. Instead, the Guideway uses an innovative box structure, slightly tapered at the edge to lighten the silhouette. The round and narrow profile of the double columns enhances safety by increasing visibility. The double columns also enable the skylight to run through the centre of the Guideway, allowing light and water through to support plantings and activities below.

Cross section of different guideway designs

At Campbell Avenue Park, the underside of the Guideway is between 5.0 metres and 5.8 metres above ground, and between 8.6 metres and 9.4 metres to the top of the stainless steel cladding. Approaching Dupont Street, the underside is 6.4 metres above ground, and 7 metres above ground at its highest point where it crosses the CP track just north of Dupont Street. The overall effect of the design is a physically and visually lighter bridge with safer, naturally lit spaces underneath that are capable of sustaining partial sun native plantings. Shadow studies show fairly minimal shadowing impact of the bridge on the residential properties next to the rail corridor.

Under the guideway

The top of the Guideway stainless steel cladding at the residential area near Wallace Avenue is just over 7.5 metres high, about the same height as the peak of the typical two-storey houses in the neighbourhood. The skylight allows for significant natural light beneath the structure. The laneway at the back of the houses north of Erwin Krickhahn Park would have a similar condition to the existing shadow condition cast by the existing noise wall. The impact of the shadowing of the bridge on the trees at Campbell Avenue Park is minimal since the canopy of these mature Siberian Elms is mostly above the level of the bridge. 

Trees reach above the guideway

The Guideway and Greenway

The initial Guideway and Greenway concept takes a progressive design approach to building advanced, community-friendly transportation infrastructure. A modern Guideway has been specially designed with a continuous rib- bon of lightly polished steel panels to gently reflect light, blend in with its surroundings, and visually lighten the structure. The length of the raised Guideway or bridge has been minimized to 570 metres, and its structure elegantly shaped with thin round columns that make it lighter. It reduces noise by eliminating the clacking noise at the Diamond, and incorporating noise and vibration control at the base of the columns.

Beneath the Guideway will be a new linear park that builds on the success of the West Toronto Railpath. This Greenway will connect local streetsand parks, and provide a range of all-season amenities to cyclists and pedestrians. The Greenway also features a new pedestrian bridge over the existing Davenport Diamond, a new linear park at Wallace Avenue to support and enhance the existing retail strip, a new illuminated path for pedestrians and cyclists reconnecting Paton Road. Public art installations will be prominently sited along the Greenway, particularly at east-west connections. 

Beneath the guideway in daylight

Beneath the guideway at night

 

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