Title
Consider an ordinance amending Chapter 36, Code of Ordinances (2010 Edition), regarding connectivity requirements for new residential subdivisions. (Second Reading)
Body
This is the second code amendment City Council will consider at this meeting regarding the Round Rock Zoning and Development Code.
In response to concerns from residents about traffic flow through and between neighborhoods, staff has created subdivision connectivity requirements. The goal is to require subdivision design to provide multiple ways to get into, out of, and around new residential subdivisions. There are two primary methods for increasing connectivity: requiring more streets to intersect with one another, and requiring more connections to public streets. Other tools include requiring stub streets to vacant properties to encourage connectivity in the future, and placing limits on block lengths.
The first primary method is calculated with a connectivity index (CI), which is a ratio of the number of street segments (links) to intersections and end points (nodes). Transportation and planning literature have determined that a CI of 1.40 or greater is the indication of a well-connected subdivision. The amendment proposes a minimum roadway CI for new residential subdivisions of 1.35, with any subdivision having a CI below 1.40 required to incorporate enough pedestrian links to bring the total CI up to at least 1.40. For reference, a random sampling of 35 existing Round Rock neighborhoods representing a wide geography and age was determined to have a mean CI of 1.36, and of those, the 8 which were platted in the last 5 years had a mean CI of 1.39.
The amendment also proposes new residential subdivisions to have a minimum number of connections to existing public streets, a minimum number of stub streets to adjacent vacant properties, and a block length limit of 1,000 feet. This limit can be exceeded with P&Z approval, but an interrupting feature must be placed near the mid-point of the block. There are opportunities to vary from any of the requirements where unique site conditions or incompatible adjacent land uses make strict compliance impossible or impractical.
The benefits of subdivision connectivity are plentiful: reduction in travel time and distance for drivers, less burden on collector and arterial streets, more convenient walking and cycling for residents (such as children going to a friend’s house), faster and more efficient emergency response, and more efficient public service (trash collection, mail delivery, etc.).
P&Z Recommendation: the Planning and Zoning Commission unanimously recommended approval of the creation of subdivision connectivity requirements. The Commission also instructed staff to meet with the home building community to seek feedback on the requirements and refine them further if necessary. As a result of the meeting, which took place on January 11, 2017, with representatives from six builders/developers, the following adjustments were made:
• Reduced the minimum connectivity index from its original value of 1.40 to the requirement noted above;
• Reduced the minimum requirements for connections to public streets and new stub streets to adjacent vacant properties for subdivisions with more than 300 lots; and
• Expanded the list of site conditions/features which allow a variance from the requirements.