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SB 743, a landmark piece of legislation in California, is transforming the way traffic impact assessments are conducted. This blog post delves into the significant changes brought about by SB 743, highlighting the shift from Level of Service (LOS) to Vehicle Miles Traveled (VMT) and its implications for urban planning and development.

Understanding SB 743

Senate Bill 743, enacted in 2013, mandates a new approach to evaluating transportation impacts under the California Environmental Quality Act (CEQA). The bill shifts the focus from Level of Service (LOS), which measures traffic congestion, to Vehicle Miles Traveled (VMT), which considers the environmental impact of driving.

The Shift from LOS to VMT

Level of Service (LOS): Traditionally, traffic impact assessments used LOS to gauge the efficiency of roadways based on congestion levels. High LOS scores indicated smooth traffic flow, while low scores signified congestion and delays.

Vehicle Miles Traveled (VMT): SB 743 replaces LOS with VMT, measuring the total miles driven by vehicles within a project area. VMT reflects the broader environmental and social impacts of traffic, such as greenhouse gas emissions, energy consumption, and public health.

Implications for Traffic Impact Assessments

Environmental Benefits: By prioritizing VMT over LOS, SB 743 encourages developments that reduce reliance on single-occupancy vehicles, promoting sustainable transportation options like walking, biking, and public transit. This shift supports California’s climate goals by reducing greenhouse gas emissions.

Urban Planning: SB 743 Analysis fosters more efficient land use by encouraging infill development and discouraging sprawl. Projects in transit-rich areas or those that provide alternative transportation options are more likely to meet VMT thresholds, promoting smarter growth.

Development Approvals: Developers must now assess and mitigate VMT impacts rather than focusing solely on traffic congestion. This change requires a holistic approach to project planning, considering the overall transportation network and its environmental impact.

Case Study: UrbanGreen Development

UrbanGreen Development, a mixed-use project in a suburban area, illustrates the impact of SB 743 on traffic assessments:

Initial LOS Assessment: The project initially faced challenges due to potential congestion impacts, with a low LOS score indicating significant traffic delays.

VMT Assessment: With the shift to VMT, UrbanGreen focused on integrating sustainable transportation options. They added bike lanes, improved pedestrian pathways, and enhanced access to public transit.

Positive Outcomes: The project met VMT thresholds, reducing environmental impact and gaining approval. The enhancements also increased property values and attracted environmentally-conscious tenants.


SB 743 marks a pivotal change in traffic impact assessments, moving beyond Level of Service to a more comprehensive Vehicle Miles Traveled metric. This shift not only aligns with California’s environmental goals but also promotes sustainable urban development. Developers and planners must adapt to this new framework, focusing on reducing VMT to create healthier, more sustainable communities.

Note: The examples and data used in this blog post are illustrative and based on general estimates. Actual results can vary based on specific circumstances and the current regulatory framework. It’s advisable to consult with a traffic impact expert for precise recommendations tailored to your project. Know more details visit here: Urbanxroads