Seattle is the first test city for a new bike lane barrier made of recycled tires

The pitch is great: Let's take a car culture waste product that would otherwise be burned and instead turn it into a barrier to protect the lives of people biking. That's the concept behind Pretred's new Paceline barriers, which were designed with bike lanes in mind initially in response to Seattle's trouble acquiring enough pre-cast concrete barriers for SDOT's ongoing even better bike lanes" project. The company used the SDOT order as the impetus to invest in the design and tooling to create these Paceline barriers, which are now for sale to any place that wants them.

Pretred Sales Manager Matt Dunn told Seattle Bike Blog that the Paceline barriers are now the only U.S.-made bike lane barrier that is more significant than a curb and less significant than a full wall." The project was personal for Dunn, who was hit by a car while riding his bike. I wish these barriers would have been there when that happened," he said, noting, We're all cyclists in this office."

Dunn credited Cascade Bicycle Club Executive Director Lee Lambert with connecting SDOT and Pretred. The department had purchased as many of the precast concrete barriers as were available, but it still wasn't enough. If Pretred can produce a barrier that is competitive with concrete, that would be a win for all North American cities because it would mean more supply and more competition in the market. Concrete creation also requires a lot of energy and is a major source of greenhouse gas emissions. Burning tires also releases a lot of greenhouse gasses. Pretred sells itself as a more environmentally-friendly option both for creating barriers and for recycling tires. The company started in 2020 selling what they call Colorado barriers, which can be used either in place of a Jersey barrier or as a base to support weight.

When fully rebuilding a road engineers can include curbs and barriers from the start, such as the new bike lanes along the waterfront. We cannot wait for full roadway rebuild projects to build out our city's bike network, so we need tools for medium-term bike lane installs for the time between now and the street's next major repaving project. Sometimes referred to as Toronto barriers" for some reason, pre-cast concrete barriers are an excellent option for creating a significant barrier on an existing road surface. The Toronto-style barriers are shorter and skinnier than a highway-style Jersey barrier but provide significantly more deterrence than plastic reflective posts. Cities like Seattle need a barrier that protects bike lanes from motor vehicles without making streets look and feel like highways, and this is a tricky balance. DOTs would also like to avoid the need for constant maintenance.

The new tire-based barriers are a different take on the concept. The come in segments two feet long that link together. The 80-pound segments are lighter than concrete, making them easier to install and to move by hand if necessary, but this also means they are easier for motor vehicles to displace. They lie somewhere between a parking stop and a Toronto barrier, which could be the sweet spot cities are looking for if they can prove durable and effective under the strains of city streets. The material cost is about $24 per foot plus additional costs for the end treatments of each connected segment, Dunn said. Agencies can install posts on the blocks for either signage or additional reflectors, though SDOT did not do so as part of this project. Some reflective plastic posts might not be a bad idea, especially on curves and end points where strikes are more likely, though each block does have front and rear reflectors.

When struck, the tire barrier segments may get gouged but hopefully will be less likely to fully crack and fail. If they do fail, crews should be able to use regular work vehicles and tools to replace the damaged segments more quickly and easily. Concrete barriers are so heavy that they require a forklift or similar piece of machinery to move and install, which could lead to longer waits for repairs as we saw with the bike lane on the Airport Way bridge near Georgetown recently. The barrier was struck (and did its job!), but a section was left sticking into the bike lane for a while before crews could repair it.

The tire-based barriers may not leave as much damage on any vehicles that strike it, but they also should not be as difficult to repair. We don't need to imagine what this would look like because the test segment has already experienced its first major strike. I went down to Campus Parkway to check it out and found a section under the bridge that clearly got hit by something significant. Not sure if it was a car, truck or bus, though the level of damage makes me think it could have been something more on the bigger side. Bolts were bent and multiple barriers seemed to split at the bolt-mounting point. One barrier section was totally destroyed and was sitting on the roadside. In all, five or six of the segments were damaged. But because of their size and weight, they were not left blocking the bike lane in the meantime, which is nice.

Environmental benefits and concerns

The U.S. wears out a hell of a lot of tires, which are notoriously difficult to dispose of. When burned, they produce a relatively low amount of heat for a long time. That's why tire fires can last so long. They also release a lot of nasty stuff into the air.

There have been many attempts to find other creative and profitable uses for tire waste, including using tire crumbs as part of an artificial athletic or playground surface. The EPA, CDC and CPSC have been studying the possible health impacts of these surfaces, though there don't seem to be any clear conclusions yet (though we know it's bad for kids to eat them). Tires contain a lot of harmful chemicals, researchers just don't know the extent that using tires in play surfaces might lead to harmful exposure. Meanwhile, researchers at UW have identified a tire chemical - 6PPD-quinone - that is likely a major cause coho salmon population decline. The chemical gets into waterways through wear and tear from cars and trucks driving on roadways.

I asked Dunn if these tire-based barriers might contribute to the problem of tire chemicals in waterways, and he said the blocks are designed to keep tire chemicals contained within them. However, as with any tire those elements could be released if they are broken or crushed. The blocks are made of about 90% tire crumb," then Pretred uses polyurethane to encapsulate it and hold it together. When they are just sitting there getting rained on, they are designed not to release tire chemicals into the runoff, he said.