On Saturday morning at CNU, there was a great panel on expressways, focusing on the removal of riverfront expressways that cut off downtowns from rivers.
Ingrid Reed spoke about her experience in Trenton, where she was able to challenge the status quo on two grounds. First, removing the expressway would create jobs, housing and prosperity, by freeing up riverfront land for commercial and residential development. By contrast, today riverfront land is cut off from downtown by the expressway, essentially blighting such land. Second, Trenton suffers from minimal traffic congestion, so the arguments against removing the expressway are weaker than they would be in a bigger, more congested city.
Cary Moon spoke about her experience in Seattle, where the city is trying to decide whether to build a new expressway to substitute for one damaged in a 2001 earthquake. Again, the argument against a new highway is based on downtown development: a riverfront connected with downtown is a prosperous riverfront bustling with parks, people and businesses, a riverfront cut off from downtown is Blight-O-Rama. Moreover, the experience of San Francisco (where earthquake-damaged expressways were removed without drastically harmful results) shows that highway removal need not result in gridlock.
Moon pointed out that the anti-highway case is stronger in Seattle than in other cities, because even if the city plans to build a new expressway, it will have a one-year transition between the end of the old road and the birth of the new: so Seattleites will already have had a year to adjust to a status quo without a riverfront expressway. Moreover, Seattle has another expressway running through its very narrow downtown.
Moon argued that the downtown expressway was not necessary to facilitate freight traffic, because only 4% of the expressway traffic was freight; most of the traffic was just local trips seeing a shortcut through downtown. Moreover, recreating the pre-expressway street grid might actually reduce congestion, because drivers idle in traffic waiting to get on and off congestion instead of being able to use the new streets that would emerge from the ruins of the highway. She also suggested building freight-only lanes for freight traffic and bus rapid transit to soak up commute traffic.
The ultimate result: in a recent referendum, voters voted against two expressway proposals (one above ground and one that is 1/3 underground)- partially because of anti-highway efforts, but partially because supporters of each freeway alternative eviscerated each other's proposals.
Norm Marshall (of smartmobility.com) disucussed the use and misuse of traffic models. Often, state DOTs use misleading interpretations of models to justify more roads. For example, the Washington DOT stated that downtown Seattle traffic would grow from 110,000 vehicles today to 130,000 in 2030. But buried in an appendix to a DOT report are statements suggesting the contrary.
Even when DOT claims about traffic are not completely false, their data projects are flawed in a variety of ways. Their pretensions of precision overlook the possible adjustments that could take place when a freeway is torn down or not built: in addition to changing routes or using public transit, drivers could take trips at different times of day or forego them entirely. Also, freeways (or their absence) create land use changes that increase or decrease vehicle trips- for example, by facilitating downtown development (if a freeway is torn down) or sprawl (if a new freeway is built). Even if a model could accurately forecast such adjustments, transportation models can't possibly forecast broader social changes such as energy prices or social changes such as telecommuting.
Marshall's bottom line: models might be useful to test different scenarios- but any model that pretends to tell you how many cars will be in downtown Seattle in 2030 is just a pile of rubbish.
Jeff Tumlin asserted that freeways export real estate value from cities to suburbs; their absence maximizes cities' property value. He used Vancouver as an example of life without freeways: while downtown vehicle trips increased in every other Canadian city since 1995, such trips decreased in Vancouver- even while total trips (including walking/transit/bike trips) increased by 22%!
Tumlin suggested that within a downtown, freeways may actually reduce capacity, because preexisting downtown streets are destroyed to build the freeway. In short, a freeway downtown is like a pig in a parlor- the right thing in the wrong place.