Your bus is driving on a bridge made of foam

Come this fall, your OC Transpo bus will be driving over a bridge made of foam.

The currant arrangement of buses at the Tunney’s Pasture transfer station has some awkward routing, and movement is slow through the Holland intersection.

The City and RTG are going to fix that by building a new bridge over the transitway at the western edge of the station. Buses will get onto Scott via a new, less busy intersection.

The bridge will  have to be removed quickly when Phase 2 of Light Rail is underway, to extend the LRT tracks towards Westboro Station.

The solution? Make the bridge out of foam blocks.

Here they are stacked up in the transitway trench.


Yup. Just giant foam blocks, contrasting nicely with the less-giant concrete blocks making up the retaining wall in the background and the concrete jersey barriers in the foreground.


Shown below, a backhoe on the right is bringing over a fresh supply of four blocks to be stacked by the crew on top of the first few layers of blocks.


Gravel is being packed tightly to the sides to prevent the blocks from “spreading” or slipping out, and to make a sloped side.

Notice also the cut made in the retaining wall to the left, which suggests the bridge will also slope downhill from the bus transfer station on the right to the new intersection with Scott on the left:


At this rate, the bridge will be mostly in place by the end of the week. Then the road surface will be paved, guardrails, etc will be added, and by September people will be commuting to work on a bus driving on a bridge made of foam.

A bit further east, RTG is taking out a big chunk of the stone sidewall of the transitway trench to build a electrical power station for the LRT:


While unusual for Ottawa, other cities have innovative bridges too. This one, in Seattle, is a floating bridge, several kilometres long. The road is supported by a very long string of concrete barges. LRT tracks are now being added to this Bailey Bridge over Lake Washington.

aug 27 2014 347


6 thoughts on “Your bus is driving on a bridge made of foam

  1. When I travelled the transit way I’ve always like the stone side walls. Hope some of them survive. I have a question. Sticking out from the side walls near Tunny’s are some giant plastic hands. Is this art or signals for the bus drivers? I’d love to know.

  2. The use of high density foam in roadway embankments or bridge approaches is not new in Ottawa. The east abutment of the Laurier Bridge over the Rideau Canal and the Highway 417 WB embankments at the CPR crossing between Moodie and Eagleson is full of this stuff.

  3. An excellent example of short term thinking. Phase two of the LRT is most likely going to go ahead and to do that the track is going to have to be extended towards Westboro Station. That won’t be possible with this bridge in the way.

    They should have built the bridge like they do the replacements for the Queensway. Then when phase two kicks off there would be no cost or delay to replace the bridge into one in which they can work under.

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