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Research Projects

STATUS: In Progress YEAR: 2021 TOPIC AREA: Public transit, land use, and urban mobility Sustainability, energy, and health CENTER: NCST

Evaluating Alternative Strategies for Traffic Reduction in Los Angeles

Project Summary

Project number: NCST-21-18
Funding source: US DOT
Contract number: 69A3551747114
Funding amount: $99,853
Performance period: 8/16/2021 to 8/15/2022

Project description

Even if post COVID-19 employers provide increased opportunities for telecommuting, Los Angeles traffic will likely continue to be a major problem. Prior to the pandemic, Angelinos spent 104 hours stuck in traffic each year. For a typical worker, this is equivalent to a total loss of 13 working days in a year. In total, the estimates of the social cost of traffic congestion in Los Angeles add up to $9.7 billion dollars per year, or $2,408 per driver. This past February, Los Angeles METRO announced that it is exploring a new approach to tackle congestion, considering congestion pricing coupled with more high-quality transportation options. Several proposals have been discussed: one option consists of introducing a cordon toll around downtown L.A. Another option includes reducing traffic between the L.A. basin and the San Fernando Valley. Yet another would focus on reducing traffic along the I-10 corridor between Santa Monica and downtown L.A.

Using big-data from a rich network of detectors located on all freeways in Los Angeles that measure in real-time speed and flow (that is, car counts), this project will rely on statistical methods and interactive visualization techniques to develop a practical tool for policymakers to infer the effects of alternative strategies for reducing traffic congestion in Los Angeles. Specifically, we will answer the following questions: Given typical origin/destination pairs and routes that drivers follow on their journey to work at peak periods, how many vehicles would have to be removed for traffic congestion to be fully eliminated in Los Angeles? What is the resulting level of the tolls needed, and how should these tolls vary spatially and along the hours of the day? The project will also examine the current proposals being considered by METRO (and other agencies), and contrast them against this more comprehensive approach to metropolitan-wide congestion. This contrast will help to identify potential unintended effects of some of the more spatially targeted proposals being considered, and provide inputs to improve their design. For example, with localized congestion pricing in specific areas, what happens to the traffic that gets displaced elsewhere? Should public transit investments be channeled to different areas to minimize potential unintended effects of traffic displacement? And, if so, how?

Unlike other attempts to measure congestion in cities, this proposed framework offers various advantages. First, because the framework will provide estimates of the speed/flow relationships in real- time at a temporally and spatially disaggregated level, one is able to calculate exactly the number of vehicles needed to be removed at different times from specific routes and locations so that congestion is eliminated. When combining disaggregated estimates of the speed/flow relationships and congestion levels with spatially-explicit data that reflects different key aspects of the existing public transit network, the project will be able to infer the capability of the existing public transit network to absorb such trips, as well as identify locations where investments in public transit would yield the greatest benefits. Given the recent Measure M and the Long Range Transportation Plan, knowledge of the returns of public transit investments at different locations is of great importance. Second, the proposed framework will inform the design of tolls. The estimation of the speed/flow relationships and congestion at a highly disaggregated way leads itself to the calculation of the toll needed to be charged at different times of the day and locations, so that the external costs of congestion are eliminated. Finally, by matching socio- economic data at the census-block level with route and location-specific estimates of the speed/flow relationships and congestion, it will be possible to calculate the tax burden vis-à-vis benefit that a congestion toll strategy would generate on different groups of the population.


Antonio Bento
Director, Global Master of Public Policy and Director, USC-Price Environmental Initiative, Price School of Public Policy
Ralph and Goldy Lewis Hall 214
Los Angeles, CA 90089
United States
[email protected]