Pedestrian bridges are back in the news in Arlington this month with some pedestrian safety advocates protesting the proposed removal of an existing pedestrian bridge in Rosslyn. It's understandable to be a bit confused by Arlington's approach - why are we ripping down pedestrian bridges in Rosslyn, while building a new pedestrian bridge on the W&OD Trail over Langston Boulevard and proposing a new pedestrian bridge between Crystal City and National Airport? The reason is that Pedestrian Bridges are only an effective safety mechanism in certain limited contexts. In most contexts, they are an infrequently-used and expensive waste of time that are used as an excuse to not make actual useful safety improvements.
The primary issue with most pedestrian bridges is that they aren't direct routes to where people want to go, and so they don't get used. A typical pedestrian bridge requires walking fourteen times the distance of just crossing at-grade. The existing Rosslyn bridge is a great example of this - ascending to and descending from the pedestrian bridge requires either an entire flight of stairs, or taking a ramp that may or may not be going the direction that you want to continue after crossing the street. People don't want to be told to "go around" and so many continue to cross at-grade.
The existence of the pedestrian bridge, however, is often used to oppose improvements to the at-grade intersection. "Why do we need to improve this crossing?" drivers ask, if the pedestrians have that perfectly good bridge? With many changes to Langston Boulevard requiring VDOT approval, this is a significant concern in Rosslyn.
Pedestrian bridges are both expensive to build, and expensive to maintain. We must recognize that budgets are finite and make sure we are getting as much safety improvement as possible for each dollar.
In many ways, pedestrian bridges aren't pedestrian infrastructure at all, they're car infrastructure. They exist to get pedestrians out of the way so that cars can go faster and with less delay. Making a safe at-grade intersection isn't hard, but it sometimes requires inconveniencing and slowing down cars. Pedestrian bridges relieve traffic engineers and political leaders from having to make that hard choice and allow them to blame pedestrians for their own injuries - that lazy pedestrian wouldn't have gotten hurt if they had just taken the pedestrian bridge.
With all of that said, why are we still building some new pedestrian bridges in Arlington? Because in some limited contexts, they are still the best solution. For instance, when they are convenient and direct for those walking and biking, or when they are getting pedestrians across an obstacle that would otherwise be nearly impossible.
The W&OD Trail Bridge, for example, is used by the vast majority of trail users because it is more convenient for most folks than the at-grade crossing. It is ramped at both ends and since most trail users are continuing on the trail, not trying to leave the trail at Langston Boulevard, nobody is being forced to go "out of their way" to take the bridge. The bridge saves them the time that they would have spent waiting at the light and keeps them safe from cars.
CC2DCA, the proposed bridge between Crystal City and National Airport, crosses two pieces of infrastructure that would be extremely challenging to cross at-grade (railroad tracks and the George Washington Memorial Parkway) and similarly does not involve ramps that could take you of your way. Additionally, the trip to the airport, at least, would involve ascending to the 2nd floor of the building anyway in order to reach TSA security so even the grade-change is not an additional burden.
Crossing Langston Boulevard in Rosslyn is just not a context where a pedestrian bridge makes sense. To meet ADA would require extensive ramps on both ends, or expensive and slow elevators. A quick back-of-the-envelope calculation indicates around 250' of ramping at each end in order to rise 18' at the maximum 12:1 ADA slope, with 5' landings every 30" of rise. That is more than half the distance down Moore Street between Langson Boulevard and 19th, and greater than the North-South width of Gateway Park. A quick look at the Gateway Park Master Plan indicates that this area of the park is slated to be the large open lawn for events like the Rosslyn Jazz Festival, and a large percentage of the park is already devoted to ramping for other pedestrian bridges.
If a pedestrian bridge here isn't the answer, then what is? Extensive crossing improvements at-grade. Rosslyn is an urban downtown, and the rebuilt Gateway Park will be a significant attraction. Langston Boulevard can't be built like a highway anymore, it needs to become an urban street. Cars will need to slow down. Right turns on red cannot be allowed. We may need a pedestrian scramble (sometimes known as a Barnes Dance) at some of these crossings, where no cars are allowed to move while people walking and biking safely cross.
A pedestrian bridge here in Rosslyn is a failed safety strategy. We know, because we already have one. If it was going to solve our crossing problems over Langston Boulevard, then it already would have. It has not. Safe, improved at-grade crossings, and design changes to Langston Boulevard that slow down drivers are what we need to achieve Vision Zero in Rosslyn.