Analysis of Impacts – City of Walnut Creek Transportation Impact Analysis
8.4 Pedestrians/Bicycles and Transit
A comprehensive assessment of pedestrian, bicycle, and transit facilities is crucial for understanding the potential impacts of proposed developments within the City of Walnut Creek. This analysis identifies existing deficiencies, evaluates the project’s effects, and provides recommendations to enhance the multimodal transportation network.
For projects located in the Downtown area, a quantitative analysis is required to assess the existing conditions of pedestrian, bicycle, and transit facilities. This analysis includes evaluating pedestrian crossing volumes, potential changes in signal timing, and their impact on intersection and arterial operations. Additionally, it considers bicycle volumes and bikeway configurations concerning adjacent traffic volumes and roadway geometry. The analysis also examines transit stop boardings and passenger load factors to understand how the proposed project may impact transit operations.
To facilitate this evaluation, peak-period counts of bicycle and pedestrian movements at study intersections are collected per the Data Collection section of these guidelines. For projects outside the Downtown area, a qualitative assessment is conducted to identify gaps and potential improvements in pedestrian, bicycle, and transit infrastructure.
The assessment identifies locations where pedestrian connectivity is hindered due to missing sidewalks, inadequate crossing facilities, or insufficient pedestrian signal timing. It also highlights deficiencies in bicycle infrastructure, such as a lack of bike lanes or discontinuities in the bikeway network. For transit facilities, the analysis examines the accessibility of transit stops, shelter conditions, and potential conflicts between transit operations and other modes of transportation.
8.5 Significant Impact Thresholds
Significant impacts are determined based on the Level of Service (LOS) or other applicable performance measures outlined in the City’s General Plan Policies. These thresholds vary depending on the classification of the affected roadway or intersection.
Significant Impact to Intersections
A proposed project is considered to have a significant impact on an intersection if it results in any of the following:
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A signalized intersection that previously operated at an acceptable LOS begins to operate at an unacceptable LOS due to the project.
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An increase in the volume-to-capacity (v/c) ratio by more than 0.05 at a signalized study intersection that already operates at an unacceptable LOS.
Significant Impact to Routes of Regional Significance
For Routes of Regional Significance, a significant impact occurs if the proposed project leads to:
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An increase in the Delay Index from 2.0 or lower to a level exceeding 2.0.
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A decrease in the average travel speed from 15 mph or greater to below 15 mph.
Significant Impact to Bicycles, Pedestrians, and Transit Facilities
The impact on bicycle, pedestrian, and transit facilities is considered significant if the proposed project:
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Disrupts an existing facility, impacting the continuity of pedestrian and bicycle flow or access to transit stops.
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Interferes with the planned implementation of facilities outlined in the City’s General Plan, Bicycle Master Plan, or Pedestrian Master Plan.
8.6 Site Access and Circulation
An essential component of the Transportation Impact Study (TIS) is the evaluation of site access and internal circulation. This analysis ensures that the proposed project provides safe and efficient access for vehicles, pedestrians, and bicycles while minimizing disruptions to surrounding roadways.
Key elements of the site access and circulation analysis include:
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Detailed plans showing vehicular and pedestrian site access, including curb cut locations and internal circulation patterns.
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Site plans illustrating access points, lane configurations, traffic controls, and access restrictions.
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An assessment of anticipated 95th-percentile queue lengths and minimum required throat depth at access points.
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A signal warrant analysis for any proposed traffic signal at project access points.
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A review of existing and proposed off-street parking, on-street parking, and freight loading spaces.
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An evaluation of pedestrian and bicycle pathways connecting residential developments to schools, commercial areas, and transit stops.
8.7 Queuing at Study Intersections
Queuing analysis assesses whether anticipated vehicle queues at intersections will exceed available storage capacity, leading to potential traffic hazards. This analysis follows methodologies from the Highway Capacity Manual (HCM) using approved software such as HCS, TRAFFIX, or Synchro/SimTraffic.
For Downtown areas, queuing impacts are typically not considered significant due to prevailing low speeds. However, in other areas, if queue lengths exceed available storage and create safety hazards, appropriate mitigation measures are recommended.
8.8 Mitigations
The TIS must identify and evaluate potential mitigations for any significant adverse impacts identified during the analysis. These mitigations should align with complete streets principles and consider all transportation modes.
Proposed mitigation measures may include:
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Signal timing adjustments to accommodate increased pedestrian crossing times.
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Implementation of new bicycle lanes or enhancements to existing facilities.
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Improvements to transit stop accessibility and amenities, such as shelters and seating.
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Intersection modifications, including additional turn lanes or traffic signal upgrades.
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Parking and loading space reconfigurations to improve traffic flow and reduce conflicts.
A table or figure summarizing mitigation measures, their expected effectiveness, and implementation timing should be included in the TIS. Additionally, funding sources for these improvements should be identified to ensure feasibility.
This comprehensive analysis ensures that new developments contribute positively to the transportation network in Walnut Creek, supporting a balanced and sustainable multimodal system.
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