Traffic Study Requirements and Typical Components – City of Kalama
In the City of Kalama, transportation and traffic considerations are an essential part of the development review process. To maintain safe and efficient travel conditions, traffic studies are typically required when new development is expected to generate a notable increase in vehicle trips. These studies ensure that potential traffic impacts on the roadway network are properly evaluated and mitigated, and that all modes of transportation—vehicles, bicycles, and pedestrians—are taken into account.
When Is a Traffic Study Required?
A traffic study is generally required when a proposed development is anticipated to generate more than 10 vehicle trips during the PM peak hour or more than 100 Average Daily Trips (ADT). These thresholds are used to identify projects that could significantly affect the local transportation system and to determine whether further evaluation is necessary to assess their potential impacts.
Even if a project falls below these thresholds, the City may still request a focused transportation analysis depending on its size, location, and proximity to sensitive areas or constrained roadways. Ultimately, the requirement for a traffic study is determined by City staff during the initial project review or pre-application phase.
Key Components of a Traffic Study
When a traffic study is required, it must provide a comprehensive assessment of current and projected traffic conditions. The analysis should identify potential deficiencies and recommend improvements where necessary. The following elements are typically included in a traffic study for projects in the City of Kalama:
1. Inventory of Existing Roads and Intersections
The study begins by identifying the roadways and intersections that are likely to be affected by the development. This includes those expected to receive at least 10 or more additional trips during peak hours due to the project. The inventory outlines the classification, capacity, and key characteristics of each road or intersection in the study area.
2. Existing Traffic Volumes
Accurate and up-to-date traffic volume data is essential for evaluating how the transportation system is currently performing. The study must collect or reference recent traffic counts—typically during weekday AM and PM peak periods—at key intersections and along significant roadway segments within the study area.
3. Trip Generation Estimates
Using land use categories and formulas from established sources such as the Institute of Transportation Engineers (ITE) Trip Generation Manual, the study must estimate how many vehicle trips the proposed development will generate daily and during peak hours. Any assumptions or reductions—such as internal capture, pass-by trips, or multimodal access—must be clearly documented and justified.
4. Trip Distribution and Assignment
The study must make reasonable assumptions about where and how trips from the new development will be distributed on the surrounding roadway network. Trip distribution is typically based on existing travel patterns, roadway connectivity, and regional traffic models. Once distributed, trips are assigned to specific routes and intersections for further analysis.
5. Intersection Operations Analysis
The study must analyze existing and projected traffic operations at intersections that will receive 10 or more peak hour trips from the project. Intersection performance is typically measured using Level of Service (LOS) standards.
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LOS D is the City of Kalama's standard for signalized intersections.
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LOS E is acceptable at unsignalized intersections that do not meet signal warrants or where a signal is not desired.
The analysis must compare intersection operations under existing conditions and with the addition of project traffic during AM and PM peak hours.
6. Bicycle and Pedestrian Facility Assessment
The study should include a review of current bicycle and pedestrian infrastructure in the vicinity of the project site. It must identify any gaps or deficiencies in sidewalks, crossings, or bike lanes, and evaluate how the project may affect non-motorized travel. Ensuring safe and accessible options for people walking or biking is a priority for the City.
7. Safety Assessment
A traffic safety assessment is also a key part of the study and typically includes:
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Collision History: An analysis of crash data at or near study area intersections and road segments to identify safety concerns or high-collision locations.
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Sight Distance Evaluation: A review of sight lines at all proposed site access points to ensure that vehicles can enter and exit the site safely in compliance with applicable design standards.
8. Recommended Mitigations or Improvements
Finally, the study must recommend any improvements needed to address identified transportation impacts. These may include intersection enhancements, new turn lanes, signal timing changes, signage, or improvements to pedestrian and bicycle facilities. Recommendations should be realistic, clearly documented, and consistent with City standards and policies.
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