Section 4.3 – Local Residential Street Cut-Through Analysis
Overview
As cities grow and develop, the need for effective traffic management becomes paramount. In Manhattan Beach, this is particularly critical as new development and transportation projects are undertaken. One significant concern that arises in the context of these projects is the potential increase in cut-through traffic on local residential streets. Cut-through traffic refers to vehicles traveling through residential areas to reach destinations outside the neighborhood, often resulting in adverse effects on the character and function of those streets. This section outlines the requirements for conducting a Local Neighborhood Traffic Management Plan (LNTMP) to analyze and mitigate these impacts.
1. Purpose of Local Neighborhood Traffic Management Plan (LNTMP)
The primary goal of an LNTMP is to assess the potential increase in average daily traffic (ADT) volumes on designated local residential streets that could result from new development or transportation projects. This analysis focuses on identifying cut-through trips generated by the project, which could lead to congestion, increased travel times, and safety concerns for pedestrians and cyclists.
Cut-through trips are defined as vehicles using local, major local, or residential collector streets with residential land-use frontage to access a destination outside the neighborhood. This traffic can be exacerbated by development projects that add vehicle trips to already congested arterial street segments or by transportation projects that reduce capacity on those segments.
2. Prevention of Cut-Through Traffic
To mitigate the adverse impacts of cut-through traffic, project applicants should prioritize design strategies that discourage non-residential project-related trips from using local residential streets. This proactive approach involves several strategies:
- Site Design: Projects should be designed to funnel traffic onto major roadways instead of local streets. This may include the placement of entrances and exits to minimize access from residential areas.
- Traffic Calming Measures: If cut-through traffic is anticipated, the City may implement traffic calming features such as speed bumps, traffic circles, and other measures to slow down vehicles and enhance safety for residents.
The City’s Neighborhood Traffic Management Program (NTMP) provides additional guidance on traffic calming measures and implementation criteria.
3. Screening Criteria
3.1. Development Projects
For any development project, the following questions should be addressed to determine if further analysis is warranted:
- Is the project required to submit a Transportation Impact Analysis (TIA)?
- Does the development project involve a discretionary action that would be reviewed by the Planning Commission?
If the answer is "yes" to either question, specific local residential street segments must be analyzed during the transportation assessment scoping process. Additional circumstances that necessitate further analysis include:
- The project is located along a Minor, Major, or Regional Arterial Street as designated on the Functional Classification Map in the City’s Mobility Plan, and the study intersections are projected to operate at peak hour Levels of Service (LOS) E or F.
- The project could add cut-through trips to nearby local, major local, or residential collector streets based on connectivity to the roadway network.
- The project is located where adjacent local residential streets provide a viable alternative route for motorists, potentially attracting cut-through traffic.
3.2. Daily Vehicle Trip Estimation
To screen for potential daily vehicle trips, the proposed project's trip generation should be estimated using the latest edition of the Institute of Transportation Engineers (ITE) Trip Generation Manual or the methodologies outlined in Section 4.1.
4. Methodology for Analysis
4.1. Existing and Future Conditions
The analysis should include existing and future peak hour "without project" traffic conditions for the study intersections near the project site. This involves:
- Utilizing intersection analysis methodologies that incorporate ambient growth rates, related project traffic, and other relevant factors as identified in Section 4.1.
- Collecting daily traffic counts for local residential streets included in the analysis to establish current traffic volumes. This data should be adjusted for ambient growth and any related project traffic.
4.2. Estimating Project Traffic
The methodologies described in Section 4.1 should also be applied to estimate the daily and peak hour trip generation of the project. This analysis will help forecast how much additional traffic may be added to nearby congested roadways. Specifically, the analysis should address:
- The volume of peak hour project traffic that may shift from congested facilities to local residential streets.
- The amount of daily project traffic that may utilize local residential streets, taking into account that traffic patterns differ between peak and non-peak hours.
5. Recommended Actions
If the analysis indicates that the project may result in substantial diversion of traffic onto local residential streets, as determined by the NTMP Guidelines, the project applicant must take the following steps:
5.1. Public Outreach and Development of LNTMP
The project applicant should engage in public outreach efforts to gather input from local residents and stakeholders. This outreach will inform the development of the LNTMP, which should be created in consultation with various City departments and regional stakeholders.
The applicant must submit a separate scoping document for the LNTMP to the City Traffic Engineer as part of the TIA. This document should include:
- Identification of key milestones.
- A summary of the proposed process for developing the LNTMP for the residential street segments in question.
- An explanation of the proposed public outreach and consensus-building process.
- Criteria for selecting and approving any traffic calming measures.
- A funding plan for the analysis, outreach, and implementation, including contributions from the project.
5.2. LNTMP Development Process
The development of the LNTMP should follow the guidelines set forth in the City’s NTMP Handbook, ensuring that the analysis considers relevant traffic data, roadway characteristics, and existing conditions on the affected local residential streets.
The LNTMP must prioritize the implementation of effective traffic calming measures, which may include:
- Traffic circles.
- Roadway narrowing effects (e.g., raised medians, traffic chokers).
- Landscaping features.
- Changes in roadway striping.
- Speed humps.
- Traffic control devices (stop signs, traffic signals).
- Restrictive measures such as turn restrictions, physical barriers, and diverters.
It is crucial that any restrictive measures are carefully evaluated to prevent unintended consequences, such as the diversion of traffic to other local streets.
5.3. Feasibility Determination
The project applicant is responsible for determining the feasibility of any proposed traffic calming measures, considering factors such as drainage, constructability, and street design. Additionally, the applicant must lead public outreach efforts in coordination with the City Traffic Engineer.
5.4. Submission of Completed LNTMP
The final LNTMP, including a cost estimate for the proposed improvements and a funding plan, must be submitted to the City for review and approval prior to the issuance of any grading or building permits. The LNTMP should adhere to the following minimum requirements:
- A description of existing facilities and neighborhood traffic conditions.
- A detailed outline of proposed neighborhood traffic measures, including sketches of specific street modifications.
- An analysis of how traffic patterns may change as a result of implementing the LNTMP.
- A monitoring and implementation program to evaluate the effectiveness of the measures introduced.
The Local Residential Street Cut-Through Analysis is an essential component of managing traffic in Manhattan Beach, particularly in light of new developments. By proactively assessing the potential impacts of increased cut-through traffic and implementing appropriate mitigation measures, the City can maintain the safety, accessibility, and quality of life for its residents. Through a collaborative approach involving public outreach, consultation with city officials, and adherence to established guidelines, developers can help ensure that their projects contribute positively to the local transportation network.
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