Repairing I-5’s Gash Through Downtown: Put a Lid On It?

Capitol Hill Seattle Blog recently covered architect Christopher Patano’s plan to put a “lid” on I-5 through a two mile segment alongside First Hill and Capitol Hill to create a linear park. It’s an exciting idea. Obviously it would be very expensive and require a huge political lift. But let’s discuss its merits. I’ve covered the damage freeway construction did to urban neighborhoods; this is one way to mitigate that damage without sacrificing highway capacity.


Christopher Patano has proposed an ambitious two-mile linear park capping I-5 and has the renderings to envision it. (Patano Studio Architecture)

Scott Bonjukian covered this idea last year on his blog, conducted graduate research on an I-5 cap, and is planning a reveal more of his findings in an imminent blog post. His 2014 redux proposal focused on a 9.6 acre expansion of the existing Freeway Park between Pike Street and Seneca Street. He projected a $200 million price tag for this expansion. Patano insists on deflecting the question of cost for now, but Bonjukian had a longer option that went 2.5 miles from Galer Street all the way to Yesler Way, and he estimated a freeway cap that length would cost 2 billion dollars.

Detailed Lid Plan

Scott Bonjukian starts with a more modest 9.6 acre freeway cap in this 2014 proposal. (Scott Bonjukian)

That hefty price tag could be partially—perhaps even mostly—offset by selling off some of the land parcels created over the freeway trench. Bonjukian estimated that the land created in those choice neighborhoods could be worth roughly $18.1 million per acre. Meanwhile the cost of the freeway cap is estimated at $20 million per acre, based on similar projects in Dallas, Philadelphia, and the Freeway Park project in Seattle.


Seattle’s Freeway Park has an architecture about as brutalist as the name would suggest. The maze-like concrete installation hasn’t become popular with park-goers as far as I can tell, although it does have a Tumblr dedicated to it with almost 2000 notes. (Mark Careaga)

If land values continuing shooting up, one could see land values surpassing the cost of creating that land with a freeway cap. Of course, some acreage would have to be set aside for cross streets and to reserve space in the middle for the parkway with a bike and pedestrian trail.

There is also the caveat there is developers would be hindered in how high they could build and in digging parking garages over the freeway due to the obvious engineering limitations. That would likely lower the land value. However, even low rise parcels could have very high value. Plus, the lid could be engineered to support mid-rise buildings; it just have to be further reinforced, which is expensive, but the increased costs could be covered by a developer wanting the extra height.


This rendering hints at what Patano has in mind for the freeway cap in East Lake where I-5 is elevated. It appears the protected bike lane would be at street level and the park seven stories above. (Patano Studio Architecture)

Moreover, the freeway cap could present a unique opportunity for the city to guide positive urban design in a way it rarely has the power to do. Instead of lamenting limited parking opportunities, the city would create a car-light, mixed-income zone with fantastic access to the newly created bicycle and pedestrian trail, not to mention frequent transit. I expect further cost savings could be realized by integrating foundation work into the freeway cap construction so that wood apartment buildings could go up quickly. Not having to dig parking ramps saves time and money. The apartments could be targeted at low and middle income tenants without cars and looking to take advantage of the new bike trail and great pedestrian access to downtown and Capitol Hill.

The project could be done in sections. However, once the low hanging fruit are completed nearer downtown (where I-5 is in a trench), a northward expansion would require more significant engineering and probably a lengthy closure to construct a more complicated cap, such as encasing the freeway in a seven-story structure like in the rendering. It appears apartment or hotel units are built right into the structure, which might work but doesn’t exactly make for very enticing real estate.

Patano’s vision for the northern half of the linear park is reminiscent of the much ballyhooed High Line in New York City that it seems every city now wants to copy (and which New York copied from Paris’ Plantee Promenade). Park space several stories up in the sky is a nice novelty but it’s hardly central to good urban design. High Line replicas run the risk of being exorbitantly expensive, underutilized flops. The High Line works well in New York because the surrounding neighborhoods are quite dense and, to be believe the boosters, the park catalyzed redevelopment that wouldn’t have otherwise have happened in the up-and-coming Chelsea neighborhood of Manhattan. The elevated park also draws a large number of tourists.


The High Line elevated park in New York City has proven to be quite popular. (Beyond My Ken)

If your city doesn’t have redevelopment opportunities or a serious shortage of park space and tourist attractions near its planned elevated park then it might just be a vanity project. Unfortunately spending billions of dollars to build a High Line-like park on top of I-5 between East Lake and Capitol Hill might fall into that category. The downtown section of Patano’s plan seem more likely to have enough benefits to outweigh the costs. Capping the freeway downtown would provide a marked improvement to the public realm in this neglected area of the city and hopefully allow additional blocks to be developed to relieve some of the housing pressure in Seattle.


Highway Mission Creep

Last week, I wrote about the progress of the highway funding bill through Congress. A few politicians—Marco Rubio, John Kasich and Rick Santorum—don’t want to fund highways at the federal level any more, endorsing transportation devolution. I also talked about Chuck Marohn’s Strongtowns no new roads message, which has proven to have some appeal in the urbanist community.

I didn’t delve into the history of we got to the overbuilt highway system we have today. It’s a story of mission creep. President Dwight D. Eisenhower was instrumental in building the Interstate Highway System through the Federal Highway Administration (FHA). The lore goes General Eisenhower was impressed with the efficiency of German autobahn system during World War Two and sought to emulate it in the United States. The catch was Eisenhower didn’t envision plowing highways through major cities. Eric Jaffe tracked down the Eisenhower memorandum detailing his chagrin at highways steamrolling through cities in this City Lab article.

(No Exit) Fast Lane Tolls

This Andy Singer cartoon highlights the destruction urban highways have wrought on cities, offer justified with questionable traffic volume projections. (Andy Singer)

Eisenhower obviously was naive in not anticipating that once he fully unleashed the highway industrial complex, its appetite would grow, and it would set its sights on urban areas. Eisenhower went on to compound his naivete with aloofness while the FHA bulldozed through cities under his nose during his eight years in office. Much like his warning about the military industrial complex, Eisenhower’s warning about the highway industrial complex seems futile, like Dr. Jekyll saying on his way out the door: by the way I’ve created a monster, good luck with that.

(No Exit) A Highway Map of the USA

Andy Singer pokes fun at endless highway expansion in this cartoon from his book “Why We Drive.” (Andy Singer)

Once the Interstate System was set in motion, the FHA eventually did pave highways through almost every major American city, cementing suburban sprawl growth patterns and hollowing out and sapping the vitality out of vibrant urban neighborhoods. Jaffe estimated 335,000 homes were razed in the first decade of Interstate highway construction alone. Throughout its history, interstates have displaced millions of Americans. Highway planners disproportionately chose to level and pave over neighborhoods with large minority populations. In many cities, they bisected thriving black neighborhoods, hastening their decline and depressing property values.

Redlining and urban highway construction were a one-two punch that did much to impoverish black communities, proving racial oppression wasn’t just a lingering legacy of slavery, but also an active ongoing process that continued to tighten the screws on black Americans. Every American generation has found a way to put its own signature on the ongoing saga of racial oppression—segregation, discriminatory voting laws, discriminatory urban “renewal,” neglected urban schools, racial profiling and police brutality—and intermittently pay attention long enough to make some progress.

They may have chosen to level minority communities, but, at least in part, highway engineers’ intentions were good in building urban highways. Speeding interstate travel and making intercity trips more convenient is a noble goal; however, highway expansion in urban areas proved to be misguided. Congestion persisted even as cities sacrificed more and more neighborhoods—and the tax bases along with them—to the chopping block for highways. Each new highway promised to reduce congestion and commute times, but almost universally the promise rang hollow. More highways begat more traffic congestion.


This map shows the havoc that the I-94/I-35 interchange wreaked on Minneapolis. A few dozen city blocks were blasted off the map and paved. In total, Singer estimates freeway construction cost Minneapolis at least 52 million dollars per year in lost property tax revenue.  (MnDoT)


In 1968, mathematician Dietrich Braess formulated what became known as Braess’ paradox: in a congested road network, the addition of a new route will increase overall travel times. Seattle Urban Mobility Plan said the paradox can also be expressed as “the theory that direct routes often function as bottlenecks, and so reductions in total capacity can reduce congestion.” Cities have seen results that support the conclusion. Seoul saw traffic volumes decrease and property values go way up after it demolished Cheonggye Expressway, its downtown highway viaduct, and replaced it with a linear park. Stuttgart, San Francisco, Portland, New York, and Milwaukee have seen similar results when tearing down urban freeways.

Recently, Amherst professor Anna Nigurney argued the Braess paradox stops applying at sufficiently high congestion levels and a new route will have no effect on travel times, which is almost as damning and undercuts the justification for expanding urban highway infrastructure. Nigurney’s findings bolster the case against highway expansion, as Lisa Zyga explains:

In a sense, the negation of the paradox actually adds to the paradox’s original conclusions: when designing transportation networks (and other kinds of networks), extreme caution should be used in adding new routes, since at worst the new routes will slow travelers down, and at best, the new routes won’t even be used.
This academic view of highways has yet to enter the mainstream. Generally the public is very supportive of infrastructure spending. It sounds wholesome. PBS’s slant is pretty clear from this article’s title alone: The Highway Trust Fund keeps bridges from falling down, but will Congress reauthorize it? The Maddowblog couldn’t help but lambaste Republican presidential candidates for not wanting to invest in infrastructure at the federal level. It’s worth criticizing the Republican plans since cutting transit funding, an explicit goal in most GOP plans, is a bad, dangerous idea. However, to not criticize the transportation status quo is to overlook how state and federal Departments of Transportation are saddling us with an ever-growing portfolio of highways of dubious value and a massive maintenance backlog that is coming due.

Mixed Signals on the American Superhighway: Devolve, Evolve, or Prod Ahead?

Congress finally did something! It appears poised to pass a two year patch for the debt ceiling and a “six-year” transportation bill that in truth contains money for only three years and does not account for rising construction costs and dwindling gas tax revenues. The highway funding bill is headed to conference to hash out differences in the senate and house versions. Our country’s monstrous highway network actually needs a major infusion of cash to keep up with “business as usual” and holding spending level flat for three years will not do that. It’s just a band-aid, and not a good one at that.

Enter America’s political brain trust.

GOP wunderkind and insider favorite for the presidential nomination Marco Rubio dropped a plan titled “Letting States Pave the Way” with an enormous freeway interchange on the cover. Ever the visionary, Rubio calls the federal gas tax outdated and proposes slashing it by 80% and turning over highway funding to the states, a maneuver called “transportation devolution.” Essentially he just endorsed the Transportation Empowerment Act written by conservative ideologue extraordinaire Sen. Mike Lee of Utah and Sen. Mike Graves of Georgia (and one has to imagine largely ghostwritten by the Heritage Foundation with Koch money), which did the same thing.


Marco Rubio echoes calls for transportation devolution in which the federal government relinquishes funding responsibility to the states. (

Now, as far as serving Rubio’s stated purpose of spending even more and wider roads, cutting the federal gas tax is likely a self-defeating idea. The federal gas tax hasn’t been raised since 1993 and is falling woefully short of maintenance needs; Congress has resorted to using billions of dollars of general funds to prop up the highway trust fund. Cutting the 18.4 cent federal gas tax will exacerbate the problem and then foist it on the states. To think states would immediately pick up the slack and cover transportation costs with augmented state gas taxes or other revenue sources is very wishful thinking. State politicians might be just as tax-averse and let their state’s highway system crumble and deteriorate. On the other hand, transportation blogger Ken Orski reported that 23 states, many of them GOP controlled, considered measures to raise transportation revenue as federal funds lagged and threatened to disappear. A few unlikely states even passed measures: “Georgia, no bastion of free-spending fiscal policy, raised its fuel tax to 21.7 cents and indexed it to inflation. Maine Gov. Paul LePage, as cranky an antitax zealot as there is in the country, has proposed a new $2 billion plan to rehabilitate state infrastructure.”

(Note that most presidential candidates aren’t embracing the issue of the dwindling highway trust fund. It seems to be a bit of political hot potato. Democrats Hillary Clinton and Bernie Sanders don’t include transportation funding on their campaign issues pages, likely because progressives are split on the direction to take. Clinton did endorse an infrastructure bank last month—a plan in which the federal government would put up something like 10 to 50 billion dollars to kick start a private-public partnership for infrastructure projects with corporations or states selecting the projects and put up the money to get the loan from the infrastructure bank—although it’s not clear to what extent this could replace the federal highway trust’s role if at all.)

The Urbanist Case

Surprisingly, Rubio’s plan is similar to what some urbanists such as Strongtown‘s Chuck Marohn have suggested. Governing summed up Marohn’s unconventional message thusly:

“At a time when half of Washington is batting around numbers that purport to reveal how much money Congress should spend to save the nation’s troubled transportation system, Marohn is suggesting the simplest number of all: zero. What the system needs, Marohn says, isn’t a big infusion of cash, but a thorough examination of what it ought to be doing in the first place. Barring such an examination, he wouldn’t give the transportation system a dime.

Marohn has described our transportation system as a Ponzi scheme for years, and wrote earlier this year:

“This is our system: one big Ponzi scheme attempting to prop up a rolling development extravaganza of strip malls, big box stores, fast food and cheap residential housing. You want to spend more on this? … I’m going to aggressively oppose any increase in transportation funding in Minnesota, any other state or at the federal level, until there is aggressive reform of this system. At this point, communal funds must be for maintenance only with any system expansion being paid by some form of user charge.”

Getting rid of the federal highway trust fund and turning over responsibility for the highway system to the states would give states more autonomy notwithstanding the giant new budgetary obligation. Rubio would have states focus on freeway capacity and slash transit funding. Marohn and his ilk would likely do the opposite. Either way there is some unlikely consensus from folks on the political far right and certain urbanist thinkers that transportation devolution is the way to go.

If devolution did happen, it seems possible that urban states with popular mass transit systems such as New York, Illinois, California, Massachusetts and Washington would use their greater autonomy to devise ways to boost transit funding. However, predominantly rural states would keep the focus on highway expansion, and I don’t see our country’s many Republican controlled state governments boosting the state gas tax enough to maintain their colossally overbuilt systems. The fear then is that poor states would shirk on their responsibility and let their highways fall into disrepair. Eventually we would see the interstate highway network develop gaps, perhaps most of all in the Deep South, Appalachia and the sparsely populated West. There are also reasonably wealthy cities that massively overbuilt their highway networks such as Kansas City, St. Louis, and Houston (the top three cities in highway lane miles per capita according to this study) that might struggle mightily to keep up with maintenance without the federal government to bail them out.

Republicans have complete control of 30 state legislatures and 32 governor's mansions. Devolution would have to come to terms with that reality or one similar to it for the foreseeable future.

Republicans have complete control of 30 state legislatures and 32 governor’s mansions. Devolution would have to come to terms with that reality or one similar to it for the foreseeable future. (Washington Post)

Now the real fairy tale ending to this scenario is that these cash-strapped state DoT’s (departments of transporation) would then see the error of their ways and the unsoundness of investing in highway capacity and turn to improving more versatile and profitable city streets within the grid and encourage multi-modal living and smart growth. That’s the dream anyway for urbanists who support devolution.

The Climate Change Argument

Another argument for devolution is that cutting the federal purse strings would shock state DoT’s into fiscal restraint or starve them out of their consumptive practices, pulling us out of our spiraling cycle of induced demand via endless highway expansion. The status quo is steadily paving over our exurbia, choking our skies with greenhouse gases, and allowing us the lead the world in carbon emissions per capita. That’s not the leadership Obama et al are referring to when they talk about American leadership on climate change, and, as we approach Paris Climate Talks, America’s emission heavy ways frankly undermine its message and self-proclaimed leadership role.

This graph of carbon emissions per capita per country are based on 2007 numbers.

This graph of carbon emissions per capita per country are based on 2007 numbers. (International Rivers)

Concrete is a large and often overlooked contributor to carbon emissions. In her article Cement Industry Is At The Center of Climate Change Debate, Elisabeth Rosenthal said, “Cement plants account for 5 percent of global emissions of carbon dioxide, the main cause of global warming. Cement has no viable recycling potential; each new road, each new building needs new cement.” Much of the emissions result from the chemical reaction that produces cement; thus, it’s difficult to make an environmentally friendly concrete. (Using fly ash, a by-product from coal power plants helps but coal is hardly a fuel of the future.) Generally, a ton of concrete produces nearly a ton of carbon emissions.

Asphalt has its own problems, and it’s used to surface 90 percent of highways (although it typically rests atop concrete base.) In a National Geographic News article, Marianne LaVelle reported, “Conventional hot mix asphalt must be heated to 300°F (150° C) or more so that it is workable during mixing, laying, and compacting. But by introducing water into the asphalt mix through foaming agents, or with the help of additives such as waxes, asphalt makers have found they can reduce the temperature of the mix by 50° to 100°F (30 to 60°C), while still providing a road-surface medium with the same properties as hot mix.” The industry is also moving toward recycling old asphalt. “The U.S. industry, which is now producing about 400 million tons of new asphalt paving annually, reclaimed about 73 million tons in 2010,” LaVelle said. That reclaimed asphalt is used instead of virgin rock, which is a scarce resource in itself. Rock makes up more than 90 percent of both asphalt and concrete and mining, crushing and hauling it consumes a colossal amount of energy.

Another important factor to consider is how road smoothness effects the fuel efficiency of cars using the roads. Rough roads can decrease fuel efficiency by as much as 5 percent compared to smooth roads, which is a big deal in the grand scheme of cutting carbon emissions. This would suggests highways, particularly busy ones, should be assiduously maintained for optimal smoothness to boost the fuel efficiency of cars passing over them. It’s precisely what we are not doing now as Seattlites motoring across the many washboard sections of I-5 can attest. This focus on maintenance dovetails nicely with Marohn’s no new roads mantra.

I don’t know if devolution is the answer. I certainly agree with Marohn that our highway network is overbuilt and building new roads should not be the goal. Returning DoT’s focus to maintenance would spare us the added costs and Paul Bunyan sized carbon footprints of new highways while maximizing the efficiency of highways we already have. Alas, new roads are seen as a sexy investment with an easy political constituency while maintenance is seen as boring and an easy thing to put off and pay for later. Delaying maintenance exacerbates the problem as repairs get more and more expensive the longer you wait and DoT’s meanwhile pile on new highways that will also get thrown on their massive maintenance backlog. It’s a vicious cycle seemingly headed to bankruptcy and ruin. Devolution would grant states the opportunity to re-calibrate their budget priorities and perhaps get themselves on a more sustainable course. If the states would really take the opportunity to change their ways is another question entirely.