All in the Details: Street Design Guidelines within Transit Oriented Development
By Catherine Velarde.
“Planning is bringing the future into the present so that you can do something
about it now.” - Alan Lakein
When planning for Transit Oriented Development (TOD) there are many elements to consider, including setback requirements, minimum dwelling sizes, and parking requirements. In addition to these components, street design plays a key role in the efficacy of transit-oriented development. Specific details, such as lane width and bike lane design have the power to hinder or enhance a TOD’s functionality - thus, consideration of these details during the planning phase is paramount. While there are many components of urban street design, this article reviews some important best practices for the design of three key features: streets, sidewalks, and bike lanes.
There are various street design elements which can greatly impact whether people choose to walk, ride bicycles, use transit, or drive personal vehicles. One key feature which impacts the overall design of a thoroughfare are lane widths. The National Association of City Transportation Officials argues that lane widths of 10 feet have a positive impact on street safety without affecting traffic operations (1). Historically, favored lane widths have provided generous buffers for drivers (11-13 feet) because smaller widths were assumed to decrease traffic flow. New research refutes this claim, arguing that narrowing lanes from 12ft to 10ft has no impact on urban street capacity (2). As such, there is great opportunity for the redesign of existing streets. Consider a traditional, one-way urban street with three 12ft travel lanes and a 12ft parking lane (48 sq. ft total). This same street could be redesigned to include a 11ft bus lane, two 10ft travel lanes, an 8ft parking lane, and a 9ft bike lane (with buffer). Reducing lane widths can positively impact the pedestrian realm by lowering travel speeds, making pedestrian activity safer and more feasible.
Sidewalks play a key role in urban life. Proper sidewalk design can promote walking, increase connectivity, and serve a vital role in enhancing economic and social activity. A sidewalk can be viewed holistically or as a sum of its parts. A sidewalk has four main zones: the frontage zone, pedestrian through zone, street furniture/curb zone, and the enhancement/buffer zone. The frontage zone operates as an extension of the building, with entryways, doors, and sidewalk cafes. The pedestrian through zone is primarily used for walking and should be 8-12 ft wide in commercial areas. The street furniture/curb zone provides space for amenities such as benches, tree pits, bike parking, and kiosks, while the enhancement/buffer zone may consist of various elements such as stormwater management features or curb extensions. Each of these zones play an important role in street life and should be planned for within a TOD. In order to encourage pedestrian activity, sidewalk design should go beyond bare minimums and consider other elements such as lighting, shade, and appropriate scales.
Just as well-designed sidewalks can encourage pedestrian life, well-designed bike lanes can encourage cyclist participation in an urban area. Buffered bike lanes appeal to bicycle users by contributing to the perception of safety, while providing a greater distance between bicyclists and motor vehicles. For high speed roads, a buffer of 3ft or wider is suggested. While the recommended width of bike lanes depends on the street and other features (such as parking), the National Association of City Transportation Officials recommends 6ft of bike lane adjacent to a curb and 4ft adjacent to a street edge. In addition to buffers, including bike lane symbols and arrows also assist in enhancing safety and visibility.
Street life is a sum of its parts and small details (often the difference between a foot or two) can greatly enhance the pedestrian and multi-modal experience within a TOD. Pegasus is currently working with Horizon City, TX to create a TOD ordinance for their central district. An integral aspect of the ordinance writing process has been the consideration of the best applicable street design guidelines for their TOD.
1. National Association of City Transportation Officials. (2015). Urban Street Design Guide. Retrieved from https://nacto.org/publication/urban-street-design-guide/street-design-elements/lane-width/
2. Appendix A-P, p. A152, Florida Department of Transportation (2007). Appendix A-P and Appendix Q. Conserve By Bicycle Program Study Final Report. Tallahassee, FL: FDOT.