TRAFFIC IMPACT ASSESSMENT

What is Traffic Impact Assessments?

A traffic impact assessments is a study which assesses the effects that a particular development’s traffic will have on the transportation network in the community. These studies vary in their range of detail and complexity depending on the type, size and location of the development. Traffic impact assessment should accompany developments which have the potential to impact the transportation network. They are important in assisting public agencies in making land use decisions. These studies can be used to help evaluate whether the development is appropriate for a site and what type of transportation improvements may be necessary. 

Traffic Impact Assessment help communities to: 

• Forecast additional traffic associated with new development, based on accepted practices. 
• Determine the improvements that are necessary to accommodate the new development. 
• Assist communities in land use decision making. 
• Assist in allocating scarce resources to areas which need improvements 
• Identify potential problems with the proposed development which may influence the developer’s decision to pursue it. 
• Allow the community to assess the impacts that a proposed development may have. 
• Help to ensure safe and reasonable traffic conditions on streets after the development is complete. 
• Reduce the negative impacts created by developments by helping to ensure that the transportation network can accommodate the development. 
• Provide direction to community decision makers and developers of expected impacts. 
• Protect the substantial community investment in the street system.

What should be included in a traffic impact Assessments?

I. BACKGROUND:  Description of proposed development  Identification of peak hours and whether weekends will be used in the impact analysis Description of study area Location of proposed Access points  II. BASE TRAFFIC CONDITIONS:  Description of road network and intersections adjacent to site and at access points Counts during peak-impact hours  III. SITE TRAFFIC GENERATION: Trip generation rates used and the source of these rates Traffic generated during peak impact hours  IV. SITE TRAFFIC DISTRIBUTION: Method used to distribute traffic Table showing estimated traffic movements by direction Discussion of method used for traffic assignment and assumptions for assignment of traffic to network V. NON-SITE TRAFFIC PROJECTIONS: Definition of design year—opening of proposed development Identification of development in study area whose traffic is to be included in calculations Adjustments of off-site through traffic volumes Assembling of off-site traffic forecast for design year VI. TRAFFIC ASSIGNMENTS: Assignment of peak-period traffic to intersections and access points Figures for existing peak impact traffic hours, site traffic and total traffic Recommended access design improvements VII. REVIEW OF SITE PLAN: Internal Reservoir at access points Parking layout Loading dock locations and access, including design truck used Recommended changes  VIII. DISCUSSION OF FUTURE TRAFFIC CONDITIONS: Other developments in area

(Community Guide to Development Impact Analysis by Mary Edwards)