Neighborhood traffic management: Dade County, Florida's street closure experience

Institute of Transportation Engineers. ITE Journal, Jan 1998 by Castellone, Anthony J, Hasan, Muhammed M

* Movement restrictions;

* One-way streets;

* Multi-way stop signs;

* Gateway treatments;

* Raised islands/medians;

* Speed humps;

* Slow point (neckdown);

* Chokers;

* Roundabouts;

* Semi-diverter;

* Diagonal diverter; and

* Street closure.

Levels of Traffic Calming

Several category levels were developed to distinguish those least restrictive (passive) traffic control measures (e.g., signing, pavement markings) from those (active) traffic control measures that are most restrictive5 (e.g., diagonal diverters, street closure). It should be noted that among each of the categories to be defined, there could be many design variations unique to each device. The least restrictive measures to address a traffic problem would be employed first (Category I), followed by more active and physical traffic calming devices (Category IV). This incremental approach would allow a cost effective measure to identify the real traffic problem, if any, and better evaluate the impacts of more restrictive measures.

Legal Implications

Metropolitan Dade County is currently investigating legal opinions regarding the equal rights of its citizens to the lawful use of the public streets and highways within its boundaries. Some government agencies already have addressed the legal issues of traffic regulation within their municipalities. According to the City of San Buenaventura, Calif., USA's "Policy Relative to Closure or Modification of Traffic Flow on Public Streets," chartered municipalities may regulate traffic within their jurisdictional boundaries in order to ensure public safety and health but, absent express authority, may not determine which traffic shall and which shall not use its local streets.6

A NEW PROCESS

Future street closure or traffic flow modification within Dade County and its municipalities will be limited to residential local streets and residential collector streets. Prior research7 has found that a residential street begins to lose its livability when traffic exceeds 1,500 vehicles per day (vpd) or 150 vehicles per hour (vph). Similarly, the thresholds for a residential collector are 3,000 vpd and 300 vph, respectively. These values represent recommended guidelines for use by engineers as part of the evaluation process. When evaluating the traffic impacts and livability impacts of traffic calming alternatives, the evaluator also must consider and analyze the effects of the implemented alternatives on:

* Speeds;

* Cut-through traffic;

Level of service-within neighborhood;

* Level of service-neighborhood periphery;

* Accidents and safety;

* Neighborhood cohesiveness;

* Emergency service access-fire/medical;

* Right-of-way requirements;

* Environment (noise, air pollution); and

* Comfort level and livability.

The following requirements must be met prior to MDCPW considering requests for traffic flow modifications (TFMs) including street closures:

* The facility must be classified as a local street or local collector;

* Commitment from the applicant to acquire additional right-of-way, if needed for cul-de-sacs or turnarounds;