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Summary of "The Impact of Adopting Time-of-Day Tolling: Case Study of 183A in Austin, Texas"

Core Content

This report evaluates the potential traffic and revenue impacts of implementing a time-of-day tolling system on the 183A Turnpike in Austin, Texas, for the Central Texas Regional Mobility Authority (CTRMA). The study is based on a stated preference survey and discrete choice modeling to understand how motorists would respond to different tolling structures. The goal is to determine whether reducing off-peak tolls on 183A can help alleviate congestion on downstream roads (such as the Missouri-Pacific [MoPac] Expressway) without compromising revenue.

Main Findings

• Traffic and Revenue Impacts: Shifting to a time-of-day tolling system on 183A is unlikely to meet CTRMA's objectives due to the constraints on revenue neutrality and toll rate changes.
• Revenue Reduction: Reducing off-peak tolls will lead to a decrease in revenue, although the losses are expected to be small for modest reductions.
• Behavioral Response: Motorists are more likely to shift from the untolled 183 to the tolled 183A when off-peak tolls are reduced, rather than changing their departure times.
• Congestion Reduction: There is little effect on peak-period traffic conditions on 183 or downstream facilities like MoPac, as the shift in traffic is primarily from 183 to 183A.
• Revenue Neutrality: To maintain revenue neutrality, any reduction in off-peak tolls must be offset by a modest increase in peak tolls.

Key Information

Survey Methodology

• A stated preference survey was conducted in 2014 to gather data on travel behavior and preferences of 183/183A corridor users.
• License Plate Reader (LPR) data were used to identify potential survey participants.
• A total of 10,000 license plates were randomly selected from 48,982 unique plates observed in the corridor.
• 551 survey responses were collected, resulting in a 5.5% response rate.

Demographics of Respondents

• Gender: 57% male, 39% female, 4% prefer not to say.
• Age: Most respondents (56%) are between 45–64 years old.
• Income: Over half (55%) of respondents reported an annual gross household income of $100,000 or more.
• Employer Flexibility: 59% of respondents indicated their employer allows flexible work hours.
• Race: 86% white, 6% Hispanic, 4% Asian, 2% Black, 2% other.

Travel Behavior

• 34% of respondents used 183A in their last southbound trip, consistent with LPR data.
• Mandatory trips (work, school, etc.) make up about 70% of all trips in the corridor.
• Nonmandatory trips are more flexible and have lower values of time.

Choice Models

• Discrete choice models were developed to predict both departure time and route choice based on the survey data.
• These models were applied to southbound trips between 5 a.m. and noon.
• The models are structured as nested logit models (see Figure 2.4).
• Value of time estimates from the mandatory model: $12.13 per hour.
• Value of time estimates from the nonmandatory model: $6.89 for single-occupancy vehicles and $10.28 for higher-occupancy vehicles.

Revenue and Toll Implications

• Reducing off-peak tolls leads to revenue loss, but the impact is minimal for small reductions.
• Time-of-day pricing may not significantly reduce congestion on 183 or downstream roads, as the primary shift is from 183 to 183A.
• Revenue-neutral pricing requires modest increases in peak tolls to offset reductions in off-peak tolls.

Key Constraints

• Any changes to the toll structure must be approved by the Revenue Bond Trustee and CTRMA's Board of Directors.
• CTRMA prefers revenue-neutral or revenue-positive tolling changes.
• No increase in tolls during any time of day is preferred over the current flat rate.

Methodological Contribution

• The study contributes to the literature on road pricing by analyzing behavioral responses to time-of-day tolling using stated preference data.
• It highlights the importance of choice experiments in understanding how users respond to pricing changes.
• The availability of a close-to-parallel alternative route (183) makes this study unique in the context of public policy and transportation planning.

Conclusion

The study concludes that time-of-day tolling on 183A is unlikely to significantly reduce congestion on the broader transportation network, given the limited behavioral response from motorists to time shifts and the tendency to switch routes rather than departure times. The analysis supports the need for revenue-neutral adjustments to the tolling structure if CTRMA wishes to proceed with time-of-day pricing.