As the region prepares for Sound Transit 2 (ST2) investments to come online, several cities are increasing zoning capacity near future light rail stations. In some cases, this wasn’t a hard sell since many light rail stations are going in along freeways where land has typically been dedicated to malls, warehouses, and light industrial use.

One lingering question is whether by focusing our growth near freeways we are jeopardizing the health of the future residents of these shiny new transit-rich neighborhoods. Luckily, we can mitigate the roadway pollution health risks with freeway lids or removing freeway sections entirely. Such a strategy would allow us to make regional growth centers abutting freeway attractive and healthy places to live. Freeway removal tackles the problem at its source, while lids dampen the dispersal of freeway pollutants and the trees and greenery they add can absorb some of the pollution that does escape.

Momentum is starting to build for freeway lids. The advocacy group Lid I-5 won a $48,000 grant to start community outreach and a further $1.5 million from the Washington State Convention Center public benefits package. Tonight, Lid I-5 Collaborative is hosting a design presentation at Optimism Brewing to review early work from seven different teams for freeway lids in Downtown Seattle. Last fall, Lid I-5 also hosted a charrette on I-5 lid designs to reconnect the University District and Wallingford.

Both Downtown and the University District are densely populated near the freeway, meaning lids there would improve the health of tens of thousands of local residents. Moreover, lids (or highway removal) can make room for people to live in the improved neighborhoods using land recovered from freeway infrastructure.

Breathing Freeway Pollution

A recent UCLA study found the pollution spew radius of freeway was at least twice as large as previously thought–1,000 feet rather than 500 feet–and pollution can even travel one mile downwind. The implications of roadway pollution are dire. People living near freeways higher rates of asthma, other chronic respiratory illnesses, heart disease, sudden cardiac deaths, and strokes, as numerous studies have shown. The Los Angeles Times confirmed rates of particulate pollution spikes near freeways in their own analysis and created a map illustrating the impact.

Los Angeles prohibits siting public schools within 500 feet of freeways and Measure S proposed doing the same for housing but extending the prohibition to within 1,000 feet of freeways. Alas, freeways are so prevalent that such a prohibition would affect a significant portion of the city, hindering an already severely constrained city’s ability to grow. Mayor Eric Garcetti’s administration estimated the 1,000-foot rule would cover “more than 10% of land currently zoned for residential construction in the city, from Westwood to Boyle Heights and San Pedro to Sherman Oaks.” Measure S failed.

The ban-the-housing approach gets it backwards: to protect the public we should seek to eliminate the health hazard rather than the victim. In other words, either we should make freeways less harmful or remove them from our urban areas. That said, we should simultaneously rezone neighborhood interiors to allow dense multifamily housing away from freeway corridors. To do otherwise would be create a deeply inequitable city with lower-income tenants breathing in freeway pollution–unless we mitigate it–while wealthier detached single-family zones are considered off-limits. The added density will allow more frequent transit to serve these formerly exclusively single family areas.

Electric Cars Will Not Save Us

Switching to electric cars may improve our roadway pollution situation but is not a solution in itself. Here’s why:

  • Brake pollution or “tire dust” would remain a major source of pollutants.
  • Noise pollution will continue negatively impacting humans and wildlife alike.
  • Embodied carbon from cars will continue choking the air with greenhouse gases and acidifying the oceans.

Electric cars still require brakes, which are a major source of air pollution. Disintegration of tires, brake pads, and the roadway surface end up dispersing toxic particles into the air. In Pacific Northwest, “tire dust” has also been implicated in coho salmon kills as they end up in area streams and ultimately Puget Sound. Since electric cars are typically heavier than comparable conventional cars because of their large batteries, they require stronger brakes. The benefits of switching away from high-polluting diesel fuel may be outweighed by “wear-particles” from heavier vehicles braking, The Guardian reported:

Increasing amounts of wear-particles have been found in new research from King’s College London. Scientists tracked air pollution alongside 65 roads for ten years. The researchers found some roads where the air pollution benefits from improvements in diesel exhausts were outweighed by increases in particles that come from the wear of tyres, brakes and the road.

So, even though we can hope the Puget Sound region’s fleet of cars and trucks will convert to electric within a few decades, we cannot expect the problem to go away. Autonomous vehicles will not fix wear-particle issue either since robot cars do not dispense with the needs for brakes; even with electric autonomous vehicles, noise pollution will continue to be an unmitigated negative externality of freeways. Plus, whatever fuel they’re consuming, cars represent embodied carbon since their manufacture and distribution puts tons of carbon into the air. The Guardian suggested the embodied carbon of a car may even be greater than its total tailpipe emissions. If private vehicles continue to be our transportation model, we will have a very hard time reducing carbon pollution and mitigating climate change.

Neighborhoods near freeways will continue to be highly polluted unless we do something about it. Removing the freeway, like I’ve proposed for Downtown Seattle is one option. Another is to build freeway lids in highly polluted areas to improve health and quality of life. We should be doing everything we can to encourage mass transit use and remove incentives for private vehicle use. ST2 and ST3 ballot measures showed the region supports going that direction–although some politicians remain convinced cutting the ST3 budget to lower car tab fees is a priority. Adding more high quality transit lines (like the Magenta Line) and implementing a carbon tax and congestion pricing to make motorists pay more of the social cost they are externalizing on the population writ-large and on the planet’s deteriorating ecosystems.

Wilburton and Downtown Bellevue

Lid park concept for the Grand Connection between Wilburton and Downtown Bellevue. (City of Bellevue)

Bellevue is mulling an rezone proposal for the Wilburton neighborhood, which will have a light rail station when East Link opens in 2023, with comments on the Draft Environmental Impact Statement (DEIS) open until March 19th.

East Link will reach Redmond Technology enter by 2023, picking up Wilburton along the way, and extend to Downtown Redmond in 2024. (Sound Transit)

Alternative 2 is especially ambitious with 450-foot towers permitted west of the station and 250-foot buildings east of it. Unfortunately, a good chunk of the rezoned land is within 1,000 feet of I-405. Luckily, the DEIS does explore a small lid over I-405 to increase connectivity. A larger lid would have the benefit of dampening more noise and particulate pollution.

Wilburton Alternative 2. Purple = 400-foot to 450-foot zoning. Blue = 200-foot to 250-foot zoning. Green = 120-foot to 160-foot zoning. (City of Bellevue/NBBJ)

The DEIS studies how the alternatives will combine with “Grand Connections,” an effort to increase Wilburton’s connectivity. Grand Connection Option C includes a proposal for a lid over I-405 which would tie together Wilburton to Downtown Bellevue south of NE 6th St.

The Grand Connection Option C is a Lid Park. (Balmori Associates)

Bellevue projects that Alternative 1 would result in 13.1 million square feet of total development by 2035 while Alternative 2 would result in 16.3 million square feet. The no-action alternative would result in 4.2 million square feet. Alternative 1 tops out with building heights of 250 feet rather than Alternative 2’s 450 feet.

Alternative 2 at 2035 buildout. (NBBJ)

Comments on the Wilburton DEIS can be emailed to bcalvert@bellevuewa.gov with the subject line “Wilburton Draft Environmental Impact Statement.” I’d encourage people to support the more ambitious Alternative 2 and ask Bellevue to pair it with the Grand Connection Option C to create an I-405 lid to make the healthiest and most welcoming neighborhood. We should also be studying if it’d be feasible to build a bigger lid considering how much the health of future Bellevue residents is at stake.

Other places that have upzoned, or are in the midst of upzoning near freeways or major highways as light rail or bus rapid transit goes in include:

More Support For Removing I-5 Downtown

11 COMMENTS

  1. “Since electric cars are typically heavier than comparable conventional cars because of their large batteries, they require stronger brakes.”

    it is true that EV’s are typically a bit heavier than their combustion vehicle counterparts, it is important to note that both hybrids and EV’s have the ability to use regenerative braking from their electric motors, which has shown to dramatically increase conventional brake pad life. There’s plenty of emissions from tires and increased weight, but I don’t believe the data bears out that EV’s have larger brakes or increased brake pad emissions – as they primarily utilize an alternative form of braking.

    • They may have larger brakes/brake pads (which would help with stopping a heavier car in the most extreme, and uncommon, conditions), but you are correct that electric cars have the potential (which is being realized more and more with new electric cars) to drastically reduce pollution from brakes. The article completely ignores this.

      It also ignores the fact that autonomous cars, once widespread enough, could pretty much reduce brake wear on freeways to nothing (especially in combination with regenerative braking).

      Finally, yes, creating cars currently requires the production of CO2, but the life-cycle emissions of an electric car are lower than that of a gasoline car, so switching to electric cars is a positive change for CO2 emissions. This will become increasingly true as electric cars last longer and longer, as battery technology advances, and as our electricity grid relies more heavily on renewable sources of electricity (which impacts the CO2 emissions of both manufacturing and operation of electric cars).

      I highly support freeways lids, but not based on false information.

  2. In addition to the U-District and Northgate, the Roosevelt neighborhood has seen immense growth in response to the 2011 rezone and in anticipation of the light rail station coming in 2021. Unsurprisingly, much of this development is apartment buildings and within 4 to 5 blocks of I-5 (if not directly adjacent to it). As is the case in the Wallingford/U-District area, for about 30 blocks between Roosevelt and Northgate I-5 is essentially in a deep trench and is ripe for a lid (or at least a lid study). On top of the benefits laid out above, this would reconnect the Roosevelt, Greenlake, Maple Leaf, Licton Springs, and Northgate neighborhoods and create a huge chunk of land that could be put to better use. (Potentially 50+ acres, based on a very quick and dirty Google map area measurement.)

  3. Dead wrong: electric cars are the solution. Brake dust is not a problem for a vehicle with regenerative braking.

    In anything but a panic stop, all the kinetic energy of the car can be recaptured by the drivetrain, regardless of the increased weight of the batteries. Most driving is accomplished without ever touching the brake pedal, and that’s not even considering letting autonomous systems do an even better job of it.

    Needless to say, electric cars significantly reduce noise pollution as well. We’d be better off to focus on programs to turn over the local vehicle fleet more quickly to electric and plug-in hybrid vehicles than focus on impractical freeway removal or lidding.

    • I believe you are correct about the reduced brake pad dust. Tire dust is probably comparable.

      I think car noise is primarily from tires rather than engine exhaust. Less true for large trucks.

      Electric cars should leak fewer toxic fluids, which are made airborne by tires.

      • Tire noise can be reduced with new pavement techniques – grinding fine grooves into concrete for instance. Unfortunately, studded tires tear them up and quickly ruin the effects, in addition to producing their own racket. Banning studded tires is one thing I’d love to see the legislature do.

      • Tire dust is probably worse for an electric car than for a gasoline car because of the added weight and instant torque. Weight of electric cars may come down to below that of a gasoline car as the technology advances. Very true, though, that electric cars have a lot fewer liquids to leak and cause pollution.

    • Correct me if wrong, but afaik a modern Prius can capture only about 20% of the kinetic energy when breaking. Regenerative brakes are not that efficient (yet?)

      • Not all of the kinetic energy is captured as usable charge, but a modern EV can brake using only regenerative braking. The new Leaf is only going to have a brake pedal for panic stops. Tesla brake pads are essentially a lifetime item unless you drive like an idiot.

    • At high speeds most of the noise pollution is from tire noise and the noise of the car traveling through the atmosphere, which would still be an issue with electric cars. At low, neighborhood speeds, however, electric cars will make for a much, much more pleasant city experience (as long as some idiot doesn’t add or require synthetic sounds as has been suggested in the past).

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