[By Paul Goddin for Mobility Lab, published on October 10, 2013]
A new study by Arlington County Commuter Services (ACCS) examines the travel and parking behaviors of residents by looking at a sample of residential site plan buildings.
Site plan buildings are those that require special approval from the County Board in order to be developed because they need some kind of exception to the zoning ordinance (such as more units, more floor area, or fewer parking spaces). Consistent with the concept of “special exception” projects, both staff and community members have opportunities for input before the approval, and each approval raises questions about the impacts of the development into the future.
The new study begins to speak to some of the big picture questions as they relate to transportation, such as “are we still moving more people without more traffic?” and “are we parking these buildings at the right level?”
One of the more intriguing results of the study: Most parking garages neither filled nor emptied over the course of a week. Most fluctuated between 20 and 80 percent full. Several garages never dropped below 40 percent full. The maximum occupancy suggests parking supply may be too high, while the minimum occupancy, particularly in Metrorail corridors, suggests that many cars in these Arlington residential buildings are not used for commuting, and in fact may be rarely used at all.
The fact that garages are not being filled would suggest a tendency to overestimate the number of needed parking-garage spaces in Arlington’s site-planned buildings, both by the County Board granting the building permits, and by developers and consumers who may favor access to parking but then fail to use the spaces. The high minimum occupancies measured, coupled with lower-than anticipated trip-generation rates across all study sites, suggest that even when households own cars, they are not necessarily using them as much as anticipated.
Education, therefore, is still needed to help consumers appreciate the transportation options in Arlington before they make a renting or home-buying decision. Decision makers, developers, and community members should also consider the connection between housing and transportation costs, and more specifically the impacts of parking supply on housing affordability, in the context of future development proposals.
The ACCS study results are an opportunity to influence policy makers involved in the county’s site-plan review process to push for a reduction of parking spaces, particularly in buildings located in the county’s Metrorail corridors. Properties developed “by-right” were not included in this sample, but since by-right parking ratios are higher than site plan approved ratios, it may be that those properties provide too much parking as well.
The ACCS research program is now underway with a similar study of commercial properties. Information on occupancy and trip generation of commercial and shared-use parking garages will provide a useful counterpoint to the residential results, informing and supporting the ongoing development of Arlington’s mixed-use urban villages.
Photo by Bossi