The Transportation Planning Rule Every City Should Reform, Eric Jaffe, The Atlantic Cities, December 5, 2011

This is a lengthy, thoughtful article about the evolution of transportation--and particularly road--planning in San Francisco, but it has broad applicability to Reston and, indeed, the rest of the United States. 

The article highlights that using the national standard "level of service" (LOS) grading system to evaluate impacts of non-auto transportation on congestion generates an inappropriate result; that is, more bike and pedestrian facilities lower the LOS grade--which is viewed as bad in an auto centric culture.  To change that mentality, it discusses how San Francisco is shifting to a different metric--automobile trips generated (ATG)--to better show the trade-off between auto and other transportation options.  Here is the summary:

Each new automobile trip added onto San Francisco's transportation system contributes to environmental impacts, especially in terms of pedestrian safety and greenhouse gas emissions. Under the proposed approach, CEQA (California Environmental Quality Act) transportation impact analysis would measure the net new trips generated or induced by proposed projects, rather than changes in automobile delay at intersections.

Instead of seeking to preserve system efficiency by expanding capacity for driving, the ATG measure recognizes that constraining the growth in automobile trips on San Francisco streets is critical for maintaining system efficiency on our network of finite automobile capacity.

The article is especially timely for Reston given the County studies now underway on the transportation impact of growth in Reston's Metro station areas on traffic congestion.  Thematically, the studies may need to look more broadly at how Reston can substitute public transit, bicycling, and walking for driving in these areas, which will be much more populated with workers and residents 20 years from now.  In particular, the studies would be of much greater value if they considered potential alternatives to driving, including better bus service, improved walking/biking facilities (including grade-separated crossings at key intersections around the Metro stations), and various traffic demand management (TDM) policies (such as parking restrictions, road diets, etc).  

It's an interesting article that I would encourage you to read.  Click here for the full text.