Palm Beach County Traffic Impact Analysis—A Prototype

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by Joseph B. Pollock, Jr., Kimley-Horn and Associates, Inc, West Palm Beach, United States,
Jacob Wattenberg, Kimley-Horn and Associates, Inc, West Palm Beach, United States,

Document Type: Proceeding Paper

Part of: Site Impact Traffic Assessment: Problems and Solutions

Abstract: A Traffic Impact Analysis (TIA) is a tool that allows government and private developers to anticipate traffic needs at the driveways of a proposed development, as well as on roadways in the area of the development. Government agencies use TIAs to identify traffic impacts and to define mitigation needs that are associated with a specific development. Developers use TIAs to identify needs for turn lanes, signalization and laneage at the site driveways. Palm Beach County, Florida has developed elaborate traffic standards titled the Traffic Performance Standards Code (TPC). These standards also include detailed analysis procedures and requirements for TIA studies. The TPC Ordinance was developed as part of the County's Comprehensive Plan as a growth management tool and is based on Palm Beach County's experience with TIAs since 1973. The primary purpose of the TPC is to provide a quality of life for residents by maintaining traffic conditions at Level of Service 'D' (LOS D) or better. The 1990 TPC contains two basis tests for determining compliance with LOS standards - Test 1 and Test 2. Test 1 is a link/buildout test which compares the projected average annual daily traffic volume on each link at the time when the project is completely developed to the LOS D daily standard. Intersection analyses are required for any links on which the project impact exceeds 10% of LOS D capacity. If LOS D or better is not attainable on a link, an Alternate Test 1 can be undertaken. Alternate Test 1 involves buildout year traffic projections for peak season, peak hour traffic conditions for each link which fails the daily test standard and requires an intersection capacity analysis of the major intersections on each end of the failed link. The Alternate Test 1 peak hour analysis is actually more representative of how a driver is affected by traffic conditions. Test 2 is a model test based upon a computer model traffic forecast which has a long range horizon - approximately 20 years. If a proposed development project generates more than 7,000 net new daily trips, Palm Beach County inserts the proposed land use into the TRANPLAN computer model.

Subject Headings: Traffic analysis | Traffic models | Computer models | Standards and codes | Model tests | Traffic signals | Beaches | Mathematical models | North America | Florida | United States

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