Roadway Segment General Plan Consistency Requirements
While intersections often represent the primary constraint for vehicle capacity and are typically the main focus of traffic analyses, there are instances where evaluating roadway segments is necessary. The City Traffic Engineer may request such segment-level evaluations to ensure compliance with the City of Calimesa’s General Plan acceptable Level of Service (LOS) standards.
For roadway segment operations, the following criteria apply and should guide project-level assessments and improvement recommendations:
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Collector and Local Road Segments:
If a collector or local road segment currently operates at LOS C or better without the project, but project-generated traffic causes the segment to degrade to LOS D or worse, improvements should be identified to restore operations to LOS C.
Additionally, if the segment operates at LOS D or worse in the no-project condition, and the project increases traffic by more than 5% of the segment’s capacity (for example, a volume-to-capacity ratio increase of 0.05 or greater), capacity-enhancing improvements should be recommended to mitigate impacts. -
Highway and Arterial Segments:
For highway or arterial segments operating at LOS D or better without the project, if project traffic causes degradation to LOS E or F, improvements must be identified to maintain at least LOS D.
Similarly, if the segment is already operating at LOS E or F in the no-project scenario and the project adds traffic exceeding 5% of capacity, improvements should be recommended to increase segment capacity.
Site Access, Safety, and Other Analyses
A thorough Transportation Impact Analysis (TIA) should include a detailed review of site access and safety considerations both within the project and on adjacent roadways. The goal is to ensure efficient, safe access while minimizing disruptions and conflicts with the surrounding transportation network. The following key analyses and recommendations are outlined:
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Intersection Sight Distance:
All on-site intersections, project driveways, and access points connecting to public roadways must provide adequate sight distance for safe vehicle movements. Sight distance requirements should follow the Caltrans Highway Design Manual or applicable local standards to guarantee visibility for drivers approaching or exiting the project. -
Driveway Length and Gated Entrances:
Primary driveways should be designed with sufficient throat length to allow vehicles to queue or enter the site without blocking public streets. This prevents spillback that can disrupt traffic flow on adjacent roadways. -
Limiting Driveway Impacts on Arterials:
To minimize impacts on arterial streets, driveway locations and access points should be consolidated where possible. Driveways should be spaced adequately from intersections or other driveways to avoid conflicts and ensure smooth traffic operations. -
Corner Clearance:
Driveways must be sufficiently distanced from signalized intersections to prevent right-turning vehicles from blocking turn lanes or queuing into intersection storage. The design should enable right-turn movements from driveways to merge safely into nearby left-turn pockets if applicable. -
Right Turn Lanes at Driveways:
For project driveways with peak hour right-turn volumes of 50 vehicles or more, consideration should be given to constructing right-turn deceleration lanes. These lanes provide a safe area for vehicles to slow down before entering the driveway without impeding through traffic on major arterials or secondary streets. Design criteria for lane length and deceleration rates should follow Caltrans guidance. -
Pedestrian Facilities:
The project should provide safe, convenient, and direct pedestrian access to and from the site. Adequate sidewalks, crosswalks, and pedestrian pathways should be included in the design to encourage walking and enhance safety. -
Bicycle Facilities:
Bicycle access from nearby bike routes or lanes should be accommodated to promote multimodal connectivity. Project design should ensure safe and logical bike routes connecting to the site. -
Transit Facilities:
The site should provide convenient access to nearby transit stops and support transit users through safe pedestrian connections, shelters, or other amenities as appropriate.
Traffic Signal Warrant Analysis
For all unsignalized intersections within the study area, a traffic signal warrant analysis is required for both the project opening year and future build-out conditions, if applicable. This analysis determines whether the volume and safety conditions justify installing a traffic signal.
The signal warrant study should be conducted following the latest California Manual on Uniform Traffic Control Devices (MUTCD). The full warrant analysis and supporting data should be included in the TIA appendices.
Where a new traffic signal is proposed on or near an arterial street, additional analysis of traffic progression and coordination may be necessary. Tools such as Synchro/SimTraffic or equivalent microsimulation software may be used to assess signal timing impacts and ensure efficient traffic flow, especially as directed by the local agency.
Improvements for Transportation Impacts
Upon completion of the TIA, the City Traffic Engineer will review and approve any required transportation improvements or fair share contributions necessary to mitigate the project’s transportation impacts. These improvements are documented as conditions of project approval and are supplementary to any other requirements imposed by other City departments or existing fee programs.
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Conditions for Fair Share Contributions:
If a transportation improvement is identified through the TIA and is not already funded through existing programs (e.g., Transportation Uniform Mitigation Fee – TUMF), the project applicant must provide a fair share contribution. -
Timing of Improvements:
Fair share payments are required before the issuance of building permits, and physical improvements must be completed prior to occupancy.
Level of Service Improvements
Mitigation for project-related operational deficiencies should aim to offset the project’s impact by restoring or maintaining the existing LOS (“no project” condition). Potential improvements include:
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Adjusting traffic signal timings
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Lane restriping
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Adding new travel lanes
For cumulative conditions, the applicant’s contribution may take the form of a fair share payment toward system-wide improvements. If the affected location is covered by a regional fee program (such as TUMF), payment of those fees satisfies mitigation requirements.
Alternatively, project applicants may consider revising the project scope or design to reduce trip generation and overall impact.
Fair Share Computation
For improvements where multiple developments contribute to a transportation deficiency, the fair share contribution is calculated based on the relative trip generation of the project compared to total future traffic. The formula used is:
Fair Share Percentage=Project TripsProject Trips+Future Development Trips\text{Fair Share Percentage} = \frac{\text{Project Trips}}{\text{Project Trips} + \text{Future Development Trips}}Fair Share Percentage=Project Trips+Future Development TripsProject Trips
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For intersection-related impacts, project trips should correspond to the peak hour when the deficiency occurs.
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For roadway segments, daily trip volumes are used.
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If a project degrades operations during multiple peak hours, the hour with the highest project trip burden should be used for assessment.
This ensures equitable distribution of mitigation costs among responsible parties.
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