A Traffic Impact Study (TIS) is required to be submitted by an applicant as part of a proposed Site Plan whenever the proposed development will generate more than one hundred (100) vehicle trip ends during the peak hour of generation according to the most recent version of the Institute of Transportation Engineers (ITE) trip generation manual. A TIS shall also be required for new phases or changes to an existing development where a traffic study is more than two (2) years old and when roadway conditions have changed significantly in the opinion of the Planning Director. A TIS is also required for a change to or expansion of an existing site where such change or expansion is expected to increase traffic volume to more than one hundred (100) vehicle trip ends during the peak hour of generation according to the most recent version of the ITE trip generation manual.
Traffic Impact Studies shall contain the following elements:
(a) Description of the Site, Surroundings, and Study Area. Illustrations and a narrative should describe the characteristics of the site and the adjacent roadway system (e.g. functional classification, lanes, speed limits, etc.).
(b) Description of the Proposed Development. A description of the proposed development shall be provided (such as the number and types of dwelling units) the gross and usable floor area, the number of employees, and shift-change factors. Any intended phasing or future expansion shall also be noted.
(c) Design Years.
The Design Year Horizon shall be twenty (20) years regardless of the size of the proposed development.
(d) Background Traffic Growth. The Traffic Impact Study shall examine "before and after" conditions in order to evaluate traffic impacts associated with the proposed development. The impacts of all access alternatives on highway capacity and throughput shall be calculated for the opening-year Build and No-Build conditions and for the design year Build and No-Build conditions using appropriate computer analysis software as agreed to by the City.
(e) Description of Existing Traffic Conditions. This includes existing traffic conditions including existing peak-hour traffic volumes (and daily volumes if applicable) on street(s) adjacent to the site. Existing counts, including turn movement counts, for intersections in the vicinity which are expected to be impacted should be provided. Traffic-count data shall not be more than two (2) years old. Roadway characteristics shall be described and illustrated. Features to be addressed include lane configurations, geometries, signal timing, traffic control devices, posted speed limits, average running speeds, and any sight distance limitations. Existing levels of service shall be calculated for intersections included within the study area. Existing driveways and potential turning movement conflicts in the vicinity of the site shall be illustrated and described. The existing right-of-way shall be identified along with any planned expansion of the right-of-way.
(f) Trip Generation: Forecasted trip generation for the proposed development during the morning (if applicable) and evening peak hour, and average day shall be calculated. This forecast shall be based on the data and procedures outlined in the most recent edition of the ITE Trip Generation Manual. Any trip reduction for such reasons as pass-by trips, transit, ride sharing, other modes, internal capture rates, et cetera, shall be based both on ITE findings and documented survey results acceptable to the City reviewers. The City may elect to reduce the trip-reduction rates used. For projects intended to be developed in phases, the trip-generation rates by phase shall be described.
(g) Trip Distribution: The projected traffic generation shall be distributed (inbound v. outbound, left turn v. right turn) onto the existing street network to project turning movements at site access points and nearby intersections. A description of the application of standard engineering procedures for determining the trip distribution shall be included (e.g. trip distribution model, market studies, counts at existing driveways, etc.).
(h) Impact Analysis: A Level-of-Service (LOS) or capacity analysis at the proposed access points shall be included. Such analysis shall use the procedures outlined in the most recent edition of the Highway Capacity Manual published by the Transportation Research Board. Before and after capacity analyses shall be performed for all street intersections where the expected traffic generation will comprise at least five (5) percent of the existing intersection capacity.
(i) Access Design and Access Management Standards: The Traffic Impact Study shall include a map and description of the location and design of proposed access (driveways or new street intersections) including: any sight distance limitations, dimensions from adjacent driveways and intersections within one thousand (1,000) feet on either side of the main roadway, data to demonstrate that the number of driveways proposed is the fewest necessary, and support that the access points will provide safe and efficient traffic operation.
(j) Mitigation/Alternatives. The Traffic Impact Study shall outline mitigation measures and demonstrate any changes to the level of service achieved by these measures. Any alternatives or suggested phasing of improvements should be described. The mitigation measures may include items such as roadway widening, turn-lane geometries, changes to signalization, elimination or combination of access points, or reduction in the proposed intensity of use. The construction and timing of roadway improvements shall be described.
(k) Qualifications of Traffic Impact Study Preparer. The preparation of a thorough Traffic Impact Study requires extensive background and experience in traffic analysis.