In my previous post, I discussed the transit productivity of freeways and showed the benefits, in terms of efficiently moving lots of people, of ensuring free flowing bus transit on freeways. But in terms of rail transit in freeway corridors, the post only critiqued rail transit in so far as reliable bus transit on freeways is often far more efficient per dollar. However, there is a second common critique of freeway based transit, which is that it can’t readily generate long-term high ridership through transit-oriented development around stations. Theoretically, I believe this claim is largely bunk and this post will address why.
The first problem with the claim is that we have counterfactuals of high-density urban development adjacent to freeways. In Seattle, for example, the section of I-5 between Lakeview Blvd. and Yesler Way (i.e South Lake Union, Capitol Hill, Downtown and First Hill) are generally covered in dense buildings that are at least five stories tall. Moreover, move one more block away from I-5 and it is hard to tell that you are near a freeway, given noise levels and development patterns. Indeed, Seattle’s tallest building is situated in just such a location. Dense development can occur near freeways and dense areas near freeways are generally walkable up to one block away from the freeway itself.
Another potential downside with freeways is the amount of space they take up. Freeways are about a city block’s worth wide and this does cut into the walkshed around a potential station. But assuming that a rail station’s walkshed is 2,600 ft. (0.5 miles) and assuming a city block takes 260 feet, a freeway will take up about 1,352,000 sq ft. (260 * 5200) out of a total walkshed of 13,520,000* or about 10% of the walkshed. That’s a significant number but hardly a deal breaker. Indeed, the 3rd avenue stations of the Downtown Seattle Transit Tunnel lose about 12.5% of their walkshed to Elliot Bay alone. And yet these stations are projected to have some of the highest ridership in the entire light rail system. In short, in terms of developable land area, freeways only have a marginal impact on the potential utility of a transit station.
Indeed, it seems the principal issues around freeway transit concern the micro issues around walkability. It is generally very unpleasant to be near a freeway and in many instances frontage roads and off ramps around freeways make the area extremely difficult to navigate on foot. If people feel like it is an ordeal to get from the station to their destination, they will be far less likely to use the service. This aesthetic argument represents the core of the transit-oriented development argument against freeway rail alignments.
But making the walk to and from that station is a problem that can largely be fixed with two key design elements. The first key design choice is to build the station at an overpass where there are no on or off ramps. This way street design near the station can be oriented principally around pedestrians who may use the station (or just walk through the area).
The second key design choice is to lid the freeway with retail on either side of the overpass, like this lid the city of Columbus built over I-670. Adding human-centered uses where pedestrians exit the station can largely eliminate the discomfort associated with walking near a freeway. The overpass feels just like a normal street and not a freeway overpass. In addition, retail lids can be built fairly cheaply with cost estimates around $10 to $20 million, due to their minimal size and their being utilized by rent-paying businesses. With this relatively small additional capital investment (stations typically cost $80 to $100 million), the transit station can integrate more or less seamlessly into the urban environment. It’s also worth noting that smart lids’ have benefits for the neighborhood as a whole by providing better means for crossing the freeway. Overall, with smart station location and effective design, accessing a freeway based rail line can feel like accessing a non-freeway based line.
Freeway-based transit alignments have the benefit of readily available right of way and minimal neighborhood pushback due to noise pollution. Thus, they can be a very effective way to provide high capacity transit in a city that lacks it. But integrating freeway based transit into the city fabric and creating useful alternatives to car dependence requires effective design. Citizens and transit advocates should push hard for the addition of these design elements to freeway stations. In order to maximize ridership and rider experience, it is very important to ensure that planned freeway stations come with meaningful investment to maximize walkability in the area.
*13,520,000 = 2 * (2,600 ^2) (the area of a square with cross sections of length 5200).