Vehicle access and falling transit ridership: evidence from Southern California

Area of Science:

• Transportation studies
• Urban planning
• Sociology

Background:

• Pre-COVID-19 pandemic transit ridership exhibited declines across the United States.
• Southern California presents a unique case study as a large transit market with demographics resembling smaller ones.

Purpose of the Study:

• To examine the factors contributing to pre-pandemic declines in public transit ridership.
• To investigate the relationship between private vehicle access and transit use in Southern California.

Main Methods:

• Analysis of administrative data, travel diaries, rider surveys, and Census microdata.
• Calculation of accessibility indices for private vehicles.
• Examination of demographic data to identify populations most likely to use transit.

Main Results:

• A strong association was found between increased private vehicle access and decreased transit ridership.
• This association was particularly pronounced among demographic groups that typically utilize public transportation.
• While not establishing causality due to endogeneity, results suggest vehicle access suppressed transit use.

Conclusions:

• Increased private vehicle access is a likely contributor to declining transit ridership in Southern California.
• Given regional similarities, rising vehicle access may explain broader transit losses across the US since 2000.