As part of GO Transit’s expansion, Metrolinx is building ‘a convenient and integrated transit network’ that among other things, includes a move towards electrifying all of its rail networks in Toronto. With the transition in the works, Metrolinx brought an infrastructural proposal before the City of Toronto's Design Review Panel (DRP) last month, to present their plan to refurbish every bridge that crosses a railway, to meet health and safety regulations associated with electrification: wherever a bridge crosses over an electrified rail corridor, the installation of a protective bridge barrier will be required so as to ensure safety regulations are met.

This poses a fairly substantial task to Metrolinx, the project's key stakeholder, given the 47 bridges in the City of Toronto alone that will be in need of these installations. Metrolinx representatives, who have been working on the project since completing a Transit Project Assessment Process (TPAP), have assessed the City’s affected bridges, in order to develop the optimal strategy to approach developing appropriate bridge barriers. 

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Bridge Categories and Scope of Electrification in Toronto, image via Metrolinx

Metrolinx have developed categorical profiles for all of Toronto’s road-over-rail bridges, which will in turn require particular designs relative to their character and usage. Five categories have been outlined:

  • Heritage bridges, which will require bespoke solutions
  • High traffic pedestrian bridges, that accommodate higher density and commercial and residential areas (in civic and institutional zones)

  • Moderate pedestrian traffic bridges, comprising lower density commercial and residential areas

  • Low pedestrian traffic bridges, predominantly in low density industrial and commercial areas, such as the 400 series highway bridges

  • Pedestrian (and cycle) bridges

Unique designs for each kind of bridge would likely be too expensive and arduous to develop, so Metrolinx’s design proposal for the barriers is based on a ‘Kit of Parts’ strategy, comprised of different design features that could be configured to suit over 80 bridge types. By standardizing bridge barrier components, the Metrolinx representatives at the DRP emphasized the versatile and easy-to-maintain nature of their proposed bridge modifications.

 

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Kit of Parts Bridge Barrier Diagram, image via Metrolinx

Of the total 47 road over electrified rail bridges in the City, there are three affected heritage buildings, 12 high traffic pedestrian bridges, six moderate pedestrian traffic bridges, nine low pedestrian traffic bridges, and seven pedestrian (and cycle) bridges. Of the remaining bridges, one already has the necessary protective barriers, four are having theirs replaced, and another will only require minor modifications. 

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Kit of Parts Makeup for Bridge Barriers, image via Metrolinx

Above all, the primary design objective for the bridge modifications are their safety. Barriers are to have a minimum height of two metres above walking surface, with no ledges on the public side of the barrier, nor any ‘openings or gaps’ on the portion of the bridge that falls directly over the electrified rail (for obvious reasons). The barriers will be predominantly supported by steel or aluminium structures, and be affixed to allow for the bridge to be inspected for structural, mechanical and aesthetic maintenance. Especially important to the proposal, as presented before the DRP and echoed by its members, is that barrier transparency be maximized, in order to retain the sensual (visible, audible) experience of crossing a bridge.

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Rendered image showing various Panel Orientation Layouts, image via Metrolinx

Enhancing the experience of the pedestrian, cyclist and motorist is a design focal point as well, while balancing regional transit priorities with municipal and local community interests through the modifications. In doing this, Metrolinx are advocating for a consistent, clean and elegant design identity for the bridges. The Kit of Parts approach to the design objectives will try to limit the number of components to the barriers, with the intention of reducing long term maintenance costs with the new barriers.

Heritage bridges are proposed to be outfitted with customized barrier designs that are ‘architecturally compatible with the existing infrastructure’ of each bridge, mounting them on the parapet structure of the bridge where that makes sense, and integrated with the existing facade. The metalwork for heritage bridges will be painted black, such that they have a uniform appearance across the City.

High and moderate traffic pedestrian bridges will also have their barriers mounted onto and integrated into the bridge's existing guardrails. Panelled elements will be integrated, transparent where possible so that bridge users can enjoy visibility while crossing. Low traffic pedestrian bridges that generally see very few pedestrians or cyclists will be comprised of predominantly opaque panels, while pedestrian bridges will all have unique, customised designs. 

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Rendered examples of Barriers on High, Moderate, and Low Pedestrian Traffic Bridges, image via Metrolinx

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Pedestrian & Cyclist Bridges will have a range of unique designs, image via Metrolinx


Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Example of Pedestrian & Cyclist Bridge Barrier Design, image via Metrolinx

The Kit of Parts approach to these modifications allows for standardized bridge panels to be fitted to the specific dimensions of a respective bridge, where they can be fitted into a base saddle structure that steps up to follow the camber of the bridge’s form and structure. The bridge panels need to meet specific design criteria, including being transparent (for high - medium traffic pedestrian bridges), durable, easy to clean and easily maintainable. This may prove challenging in winter months and in wetter whether, where road salt, slush and dirty rainwater will constantly spray the barriers. Importantly, panels - whether transparent or opaque - must be bird friendly, achieved with raised dots on the panelled material. A defining colour palette had been proposed for the panels at the DRP presentation, where internal coloured fins would lie in between the panel and back frame, to give a coloured tint.

 

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Proposed Panelling Structure including Coloured Elements, image via Metrolinx

Metrolinx, GO Transit, Electrification, Toronto, Road-over-Rail, Bridge Barrier Bird Friendly Designs for Opaque and Transparent Panels, image via Metrolinx

Members of the DRP were generally supportive of the proposal, seeing an excellent opportunity to roll out lasting changes to the City’s infrastructure fabric both electrification of the railways through the modifications to the bridges made necessary by the City’s upgrading of public infrastructure. But with these lasting changes comes a need to pay special consideration to the aesthetic appearance of the bridge barriers. Two metres is a fairly significant height, and several members of the DRP urged the project representatives to implement further design studies so that modifications don’t just become a ubiquitous example of ‘bad architecture’ in the City. ‘Artistic expression should be a fundamental part of what this intends to be’, commented one member, adding that ‘aesthetic appearance is not something to be treated in passing’. Another member pointed out the ‘heaviness’ in design associated with panelling, suggesting that having permeable wiring like on the Prince Edward Viaduct would allow for the sensual experience of crossing a bridge.

Follow us for more updates on these proposals as they develop. In the meantime, you can join in on the conversation by commenting in the space provided on this page.