3.0 METHODOLOGIES
When applicable, Level of Service (LOS) analysis is required to ensure consistency with the City of Murrieta’s General Plan. The following methodologies must be followed for intersection and roadway segment evaluations.
Intersection Analysis
The most recent version of the Highway Capacity Manual (HCM), published by the Transportation Research Board, must be used for analyzing both signalized and unsignalized intersections. The analysis should incorporate the following key parameters:
- Saturation Flow Rate: Either based on field measurements or assumed to be 1,900 passenger cars per hour per lane.
- Heavy Vehicle Factor: Derived from count data or provided by the City; a Passenger Car Equivalent (PCE) conversion may be used to account for heavy vehicles.
- Grade Consideration: Factored in based on the existing or proposed grade of the roadway.
- Signal Timing: Minimum green times should reflect existing signal timing sheets provided by the local agency or collected in the field.
- Cycle Lengths: Determined using existing signal timings or field measurements.
- Lost Time: Based on existing signal timing data or consistent with HCM recommendations.
- Peak Hour Factors: Should be based on count data, with future peak-hour factors assumed to be 0.95.
- Software Requirements: Intersection evaluations must use HCM-consistent software. Microsimulation should be utilized where closely spaced intersections create queue spillback or interactions between upstream and downstream intersections, including freeway facilities when necessary.
When considering mitigation strategies, the following thresholds should be used:
- Exclusive Left-Turn Lanes: Recommended when peak-hour volumes exceed 100 vehicles.
- Dual Left-Turn Lanes: Considered when peak-hour volumes exceed 300 vehicles.
- Protected Left-Turn Phasing: Should be implemented when peak-hour left-turn volumes exceed 240 vehicles.
Roadway Segment Assessment
In some cases, the City may require a roadway segment evaluation in addition to an intersection analysis. When conducting a roadway segment assessment, capacity values must align with the requirements outlined in the City’s General Plan, General Plan Environmental Impact Report (EIR), Appendices, or other applicable documents. If segment capacity values are not explicitly stated, the analyst should use capacity figures based on the methodologies defined in the HCM.
By adhering to these methodologies, the City ensures a standardized approach to evaluating transportation impacts, allowing for effective mitigation strategies that support both traffic operations and long-term transportation planning objectives
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