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12th International HOV Systems Conference: Improving Mobility and Accessibility with Managed Lanes, Pricing, and BRT
Conference Proceedings
BREAKOUT SESSION — HOV AND TOLL FORECASTING — WHAT'S IN THE BLACK BOX?
Don Samdahl, Mirai Transportation Planning and Engineering, Presiding
Traffic and Revenue Analysis: I-10 Managed Lanes in Houston and I-635 Managed Lanes in Dallas
Cissy Szeto, Wilbur Smith Associates and Stacey Falzarano, Resource System Group, Inc.
Cissy Szeto and Stacey Falzarano described the traffic and revenue analysis conducted for the I-10West managed lanes in Houston and the I-635 managed lanes in Dallas. They summarized the key characteristics of each project, the objectives of the study and the results of different tasks. The study was conducted for TxDOT and HCTRA.
- The I-10West managed lanes are just over 11 miles in length. The managed lanes are part of a larger freeway widening project. An additional general-purpose lane is being added and the frontage roads are being widened. The existing reversible HOV lane will be expanded to four managed lanes — with two lanes in each direction of travel and with four access points.
- The operational characteristics of the I-10 West managed lanes will allow buses to travel for free and 3+ HOVs to travel for free during the peak-periods. SOVs and two-person carpools will have to pay a toll. Pricing levels will be used to manage demand to maintain freeflow speeds.
- The I-635 managed lanes are just over 18 miles. Some improvements are being made to the general-purpose lanes and the frontage roads as part of the project. The concurrent flow HOV lanes will be converted to managed lanes. The number of managed lanes will vary from six-to-four-to-two lanes.
- The operational characteristics of the I-635 managed lanes will allow buses and 3+ carpools to travel for free. Allowing two-person carpools to travel for free and requiring them to pay a toll were both tested. SOVs will be tolled. Pricing will be used to manage demand to maintain freeflow speeds.
- The first study objective was to evaluate the projects under a range of scenarios. The scenarios evaluated included different configurations with varying access and capacity and varying HOV definitions. The second objective was to evaluate each alternative for six time periods. These time periods were 6:00 a.m. to 8:00 a.m., 8:00 a.m. to 9:00 a.m., 9:00 am. to 3:00 p.m., 3:00 p.m. to 4:00 p.m., 4:00 p.m. to 6:00 p.m., and 6:00 p.m. to 7:00 p.m. The third objective was to provide estimates of transactions and toll revenues. The fourth objective was to aid in determining potential project phasing. The final objective was to provide a traffic and revenue report suitable for use in project financing.
- The study methodology focused on determining the current demand in the corridors, the growth in demand, the base market share, and the reaction to different toll levels. The process also included a pricing analysis, traffic estimates, and revenue estimates.
- Estimating the demand for managed lanes is different from estimating the demand for toll facilities. Managed lanes are different in that they are in direct competition with the adjacent free lanes. Managed lanes are highly sensitive to changes in global demand. Managed lanes attract a small share of overall demand and it appears that travelers do not use them every day.
- Stated preference surveys were conducted to test different pricing and operation scenarios. More than 1,000 corridor travelers were surveyed about actual trips. An adaptive computer-based survey technique was used with laptop and Internet administration. Individuals were intercepted at activity center and surveys were e-mailed to workers at major employers.
- The computerized survey technique obtained information on a recent trip, including frequency, time of travel, travel time, delays, route, and occupancy levels. A description of the project was provided and participants were asked to answer a series of stated preference questions which focused on travel time and toll cost trade-offs. Questions also tested the impact of alternative concepts such as single-lane verses two-lane managed lanes, tunnels, and allowing trucks.
- The survey results indicated that in terms of value of time, the median was lower than the mean and the distribution had a very long tail. In addition, the one-lane option was less attractive by about 20 percent, a tunnel was less attractive by about 7 percent, and allowing trucks was less attractive by 22 percent.
- Pricing and operational considerations included managing demand in the managed lanes to maintain freeflow speeds, revenue maximization, and optimizing speeds in the general-purpose lanes.
Evaluating Pricing Strategies for Managed Lanes
Jianling Li, University of Texas, Arlington
Jianling Li described a recent research project conducted for TxDOT, which developed a pricing evaluation model for managed lanes. She noted the assistance of Sia Ardekani and Shekhar Govind from the University of Texas at Arlington with the project.
- The definition of managed lanes used in the study focused on a freeway corridor served by two types of travel lanes — general-purpose lanes and lanes that are managed by vehicle-occupancy, tolling, or some other strategy. Managed lanes are being implemented in specific freeway corridors in Houston and Dallas. Managed lanes are being considered in other freeway corridors in those cities and other areas in Texas. Managed lanes are also being implemented and considered in cities throughout the country.
- Price model theory suggests that the price or toll a traveler pays should be directly related to the time saved by using the facility. Thus, tolls should be higher when significant travel time savings are realized and lower when the time savings are smaller. The usage function should be related to the number of users based on different toll levels. More users can be expected to use a managed lane when the tolls are low. The number of anticipated users declines as toll charges increase. The flow model examined the anticipated time savings compared to the number of users.
- A web-based model was developed in the research project. The model can be found at the website http://transresearch.uta.edu/MLTollModel/. The model was designed to be user friendly, providing step-by-step data entry. Project specific information related to the facility characteristics, the user groups, and traffic conditions is entered first. The objectives of a managed lane project can be used to establish a toll price to maintain the speed on the managed lanes at a specific mph, to maintain the traffic flow on the managed lane at no more than a specific percentage of capacity, and to establish a desired LOS in the managed lane. For a specific objective, the model calculates the recommended toll, the projected traffic flow in the managed lane, the number of HOVs allowed to use the managed lane for free, the managed lane speed, the number of SOVs in the managed lane, and the speed and traffic in the general-purpose lanes.
- The model features include information on various user groups. The model is applicable to various geographic locations. It allows for the evaluation of toll options based on demand and desired performance. The model outputs include recommended optimal pricing policies, highlighted network performance in terms of speed and flow in general-purpose lanes and managed lanes, and estimated revenue.
- There are a number of issues that should be considered in using this model or any other model. First, a model is only as good as the input values. If bad input data is used, the model results will not be very good. Allowance also needs to be made for diversion of vehicles to alternate routes. Revealed preferences may also need to be considered. Other issues that may need to be addressed include multiple use eligibility, air quality impacts, and interoperability with other programs.
- There are also a number of implementation issues that may influence the use of different types of managed lanes. These implementation issues include the use of all electronic toll collection, the frequency of toll changes, and how drivers are informed of toll levels. Other potential issues include monitoring demand in real-time and enforcement methods. Finally, questions about social justice with different approaches may exist in some areas.
Development of a Toll Revenue Estimating Tool
Bill Stockton, Texas Transportation Institute
Bill Stockton discussed the development and use of a sketch planning level tool for estimating toll revenues funded through a TxDOT research project. He summarized the basic elements of estimating toll revenues, the assumptions behind the estimates, and the development of the toll revenue estimating tool.
- At the basic level, toll revenues can be estimated by multiplying the number of toll facility users by the toll. There are numerous assumptions or factors that may influence the demand or use of a toll facility, however. These assumptions include the total corridor traffic, the toll road traffic share, and the projected traffic growth rates. The anticipated traffic mix, which might include SOVs, HOVs, and buses, will also influence toll revenue generation. Other factors to be considered include the annual revenue days, toll rates, price elasticity, and willingness to pay.
- The toll revenue-estimating tool is a sketch-planning-level model. It is an Excel-based spreadsheet model that allows users to estimate toll revenues based on different assumptions and factors. It is not a detailed traffic and revenue study model. The toll revenue estimating tool provides transportation professionals with a better understanding of the reasonableness of revenue estimates and the assumptions used with the forecast. It also provides policy makers with an idea of the confidence intervals on revenue estimates.
- The toll revenue estimating tool can simulate a range of scenarios. The assumptions are random variables. The tool provides reasonable estimates of revenues and identifies the most critical assumptions.
- Outputs from the toll revenue estimating tool can be displayed in different ways, including bar charts and graphs. The tool allows users to run a sensitivity analysis on different assumptions. The assumptions can be modified and the analysis rerun to identify the potential impacts on revenue generation.
- The toll revenue estimating tool is currently in the final stages of review. It should be available soon for use by all interested groups.
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