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In one region, scrap tires are burned as fuel. In another, they’re recycled into products like rubber playground mats. Somewhere else, tires are a commodity—valuable in any number of civil engineering uses. For the Ragged Lake Transit Access Connector Roadway in Nova Scotia, Canada, tires were an opportunity. So, what’s in a road?

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roadway TDA project

This was the first time that a transportation project in Nova Scotia used tire-derived aggregate (TDA) in a roadway embankment application.

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busses added

The Ragged Lake Transit Centre supports the addition of 150 more busses to the Halifax fleet. With that many more busses, congestion was bound to happen, and the answer was the access connector roadway.

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scrap tires

This one project reused 800,000 scrap tires produced in Nova Scotia.

Transcript of the video follows
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<p><b>Title</b></p> <p>Civil engineering makes use of recycled tires</p> <p><b>Description</b></p> <p>Civil engineering projects often need lightweight fill. For a readily available, recycled fill, Bernie Mills chose tire-derived aggregate.</p> <p><b>Script</b></p> <p>You know there, are engineers that design using non-traditional matters, and then there’s engineers that design using traditional materials. I guess that’s what separates Stantec from some other companies—we have the technical know-how in order to take a project and design using non-traditional methods.</p> <p>I was contacted by the New Brunswick Department of Transportation because they had experienced a pretty large, significant embankment failure. Because the embankment failed, it caused the foundation soil to be weak, weaker than it already was. That’s why we needed lightweight fill.</p> <p>We looked at many options, and tire-derived aggregate (TDA) was the option that was ultimately selected. During the construction process, my understanding was that the Nova Scotia Transportation Department and Recycled Research Fund Board (RRFB), I think they got wind of this project, so they actually flew to the site to St. Stevens. They wanted to see for themselves, firsthand, how the province of New Brunswick was using this new material.</p> <p>This Ragged Lake Project is the first tire-derived aggregate project of its kind in Nova Scotia. The Halifax Regional Municipality was in the process of designing a roadway access ramp. So we reviewed it, and yes, in fact, we were able to design the TDA application for this new roadway. And because of that, Nova Scotia has adopted tire-derived aggregate as their sole-recycling method.</p> <p>There’s always a supply of recycled tires, and so because of that, finding practical civil engineering applications using TDA is a sustainable market.</p> <p>The use of TDA in transportation embankments is something that’s going to be new. Provinces across Canada can really benefit from the use of TDA. With the sustainability piece, there’s going to be some really good applications for TDA in the future. I think the future is very bright.</p> <p>We know how to design engineering applications using TDA. Because we’ve done it.&nbsp;</p>

What People Are Saying

“Provinces across Canada can really benefit from the use of TDA.”

Bernie Mills, Discipline Leader, Geotechnical Engineering

Layer upon layer

Layer upon layer

Thanks to a nearby tire-derived aggregate (TDA) recycler, the Halifax Regional Municipality (HRM) and the Nova Scotia Department of Transportation and Infrastructure Renewal (NSTIR) were already interested in the possibilities of using TDA for a roadway embankment application.

Our job was to design and manage the TDA inclusion in the roadway embankment. A lot of people picture asphalt being laid directly over shredded tires, but that’s not the case. In reality, the TDA light-weight fill layer was positioned within the embankment several metres below the top of the asphalt layer.

The three-metre (9.8-foot) thick layer of TDA is wrapped in geotextile then followed by engineered fill. After that was gravel, and then—finally—the asphalt.

Nova Scotia produces approximately 1.1 million recycled tires a year. 100 tires equal one cubic metre of TDA. This single road used 8,000 cubic metres—approximately 800,000 tires.

Re-routing design

In 2010, the Halifax Regional Municipality opened the Ragged Lake Transit Centre. The new facility complemented the existing Metro Transit Facility and added an additional 150 buses to their fleet.

Relieving strain on the Burnside Industrial Park bus facility in Dartmouth, the Ragged Lake Centre also greatly reduced operating costs by allowing buses to be dispatched from both sides of Halifax Harbour instead of only from Burnside.

With our inclusion of the light-weight tire-derived aggregate (TDA) fill, the Government of Nova Scotia recycled nine months worth of discarded tires, and saved money on engineered fill.

With this additional tool in their repertoire, the Government of Nova Scotia now has additional options for civil projects and a better alternative to trucking scrap tires out of the province for disposal.

We’re better together

Our work begins at the intersection of community, creativity, and client relationships. With a long-term commitment to the people and places we serve, we have the unique ability to connect to projects on a personal level and advance the quality of life in communities across the globe.

Bernie Mills
Principal, Geotechnical Engineering
Bernie Mills
Principal, Geotechnical Engineering

The opportunity to show how TDA can benefit projects, provinces, and the community has been extremely rewarding.… Read More

Brian Grace
Principal, Geotechnical Engineering
Brian Grace
Principal, Geotechnical Engineering

When working with a material that a lot of people consider to be rubbish, it’s rewarding to see skepticism transform into “Wow! This really works!”… Read More

James Mossman
Senior Geotechnical Technician
James Mossman
Senior Geotechnical Technician

Our infrastructure projects are what we make of them, and using the best sort of materials—like with TDA—is one way that we make great projects.… Read More

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