Business/Commerce

Add Street-Connectivity Minimums into Subdivision Ordinances

Subdivision and zoning ordinances can establish a minimum level of street connectivity for future residential developments to create neighborhoods that are conducive to walking, bicycling, and transit use. Street connectivity consists of a road and/or path network that provides multiple routes and connections between destinations. It includes parallel routes, cross connections, many points of access, and short block lengths. Minimum standards of street connectivity can be based on maximum allowable lengths of blocks or by connectivity indexes of street links to intersections.

Guidance
  • Street-connectivity standards for new developments often take the form of maximum allowable block length or an index based on the number of street links divided by the number of street nodes
  • Maximum-block-length determinations should factor in existing block dimensions, topography, and the desired scale, character, and connectivity the community aims to achieve. For example, in Portland, OR, the maximum block length is 530’; in Austin, TX, it’s 600’; and in Ft. Collins, CO, it’s 660’
  • One-way streets operate best in pairs that are no more than a quarter-mile apart
  • Align with existing local street grid to create four-way intersections
  • Introduce policies and practices to help keep travel speeds down
  • The Charlotte, NC, subdivision ordinance specifies:
    • Preferred street spacing ranges from 400’ to 600’ by context, requiring, say, three blocks for a 1,400 ft-wide property within a transit station area
    • No individual block face should exceed 1,000’ (with certain exceptions)
Benefits
  • Provides shorter, more direct routes between destinations, which encourages walking and cycling as a means of transportation
  • Reduces vehicle speeds
  • Reduces severity of accidents
  • Helps keep local trips on local streets rather than clogging arterial roads and highways
  • Provides route alternatives to drivers to avoid congestion and construction delays
  • Reduces travel distances as well as vehicle miles of travel
  • Improves both emergency access and response times
  • Allows for more efficient utility connections
  • Creates efficient trash and recycling routes
  • Facilitates bus-route and transit planning
Considerations
  • Public and developer education about the need for and benefits of frequent street connections
  • Developers may resist street connectivity requirements due to the potential decrease in developable land
Where to Use It
  • Subdivision ordinances for new developments
  • Comprehensive Plan as the basis for future regulations
  • Zoning provisions
Professional Consensus
  • Endorsed by the American Planning Association’s Model Street Connectivity Standards Ordinance
  • Endorsed by the Congress for the New Urbanism Benefits (CNU) through its Connected Street Networks
  • Supported by the Institute of Transportation Engineers through its alliance with the CNU on its proposal for federal “network” designation of areas meeting connectivity criteria. The proposal requested that all streets in a network, including sidewalks, would be eligible for investment for projects that maintain or improve the function of the network
Examples

This material is the product of a partnership between America Walks and Sam Schwartz Engineering. Visit here for more information on the partnership.