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South Dakota Department of Transportation
Project Synopsis

Title: Verify Certain ITE Trip Generation Rate Applications in South Dakota
Project Researcher: Dan Clay,
Project Manager: Hal Rumpca
Research Period: - 11/10/2005
Cost: $0.00

Problem Statement:

The SDDOT often relies on the Institute of Transportation Engineers (ITE) Trip Generation Manual to provide guidance in determining the impacts of new development adjacent to our highways. Many of the ITE trip generation rates were developed for large urban areas and therefore may over estimate the amount of traffic being generated in rural areas such as South Dakota. The SDDOT needs to verify if the ITE Trip Generation rates for major traffic generating businesses such as Wal-mart, Menards, Cabelas, and other business office buildings overestimate the amount of traffic that can be expected to be generated for these types of businesses. The Office of Road Design does not have sufficient information available to determine if the projected traffic for these businesses is accurately documented in the traffic analyses that are required as a part of the site development plan. Since traffic signals, turning lanes, and other improvements are designed and installed in response to the projected traffic volumes, we must be certain that the Manual of Uniform Traffic Control Devices (MUTCD) Traffic Signal Warrants are met before traffic signals or other highway improvements are completed. We should also review how other rural states in the mid-west use the ITE trip generation rates, to find out if their rates have been modified to more accurately reflect their rural nature.

Findings: The trip generation rates for all land uses identified in the traffic impact studies and ITE Manual were consistently low for all but two locations. Four Discount Superstores and both Home Improvement Stores had trip generation rates that exceeded the recommended rates found in the ITE Manual. Traffic count information and trip generation rates were calculated for each site and compared to the traffic impact studies and the ITE Trip Generation Manual. The signalized intersections reviewed in the various communities as a part of the research project all met at least one MUTCD traffic signal warrant and provided increased safety and convenience for the traveling public. These studies verified that the traffic signal recommendations were all based on sound traffic engineering judgment.

Research Objectives:
1  Verify if the ITE Trip Generation Rates and the NCHRP 365 Trip Generation Rates recommended for large businesses such as Wal-Mart, Home Depot, Menards, and Hy-Vee Food Store's accurately reflect the rates found in South Dakota.
2  Determine if existing traffic conditions found at large businesses accurately reflects the traffic impact studies projected traffic used to meet traffic signal warrants in South Dakota cities above and below 50,000 population.

Research Tasks:
1  Meet with the projects technical panel to review the project's scope and work plan.
2  Through review of current literature, and through contact with other states that are geographically and demographically similar, identify trip generation rates used for large businesses such as Wal-Mart, Home Depot, Menards, Cabelas, Hy-Vee Food Stor
3  Acquire and review the site traffic impact studies for the following businesses in South Dakota: · Hy-Vee Food Store on east 10th street in Sioux Falls · Super Wal-Mart and Menards in Sioux Falls · Cabelas, Menards, and Super Wal-Mart in Mitchell
4  Develop a traffic count plan that replicates the types of forecasted traffic and vehicle movements identified in the traffic impact studies.
5  Complete the required traffic and turning movement counts according to the plan.
6  Compare the traffic count information generated at each site with the traffic forecasts in the respective traffic impact studies.
7  Compare the traffic count information with estimated trip generation rates found in both the ITE Trip Generation Manual and the NCHRP Report 365.
8  Compare the information generated in tasks six and seven and determine if the existing traffic movements meet the MUTCD Traffic Signal Warrants at each of these locations.
9  Identify any trip generation rate differences found in tasks 2, 6, and 7, and recommend how the trip generation rates used for traffic impact studies should be adjusted for South Dakota cites above and below the 50,000 population threshold.
10  Prepare a final report summarizing the research methodology, findings, conclusions, and recommendations.
11  Make an executive presentation to the Research Review Board.

Documents Available:
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