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Review of the Texas Transportation Institute (TTI) 2007 Urban Mobility Report

Review of the Texas Transportation Institute (TTI) 2007 Urban Mobility Report. By Ronald F. Kirby Daivamani Sivasailam TPB Technical Committee October 5, 2007. Introduction

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Review of the Texas Transportation Institute (TTI) 2007 Urban Mobility Report

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  1. Review of the Texas Transportation Institute (TTI) 2007 Urban Mobility Report By Ronald F. Kirby Daivamani Sivasailam TPB Technical Committee October 5, 2007

  2. Introduction • “Traffic Congestion continues to worsen in American cities of all sizes, creating a $ 78 billion drain on the US economy” –press release of the Urban Mobility Report. • Report prepared by Texas Transportation Institute • First report in 1982, and repeated every few years since • Current report based on 2005 data • Following slides will review methodology, limitations, and conclusions of the report; and compare the report findings with TPB’s congestion monitoring program.

  3. Methodology • The data source for the calculations is the national Highway Performance Monitoring System (HPMS) • The primary performance measure used to estimate congestion delay is the Roadway Congestion Index (RCI) which in simple terms is a ratio of demand (VMT) to supply (lane miles of roadway).

  4. Methodology (cont’d) • Other performance measures are: Percent of daily travel in congested conditions, travel speed, travel delay (recurring), incident-related travel delay (non-recurring), person delay, travel time index, wasted fuel, and congestion cost • Travel delay is the sum of recurring delay and non recurring delay. Travel delay per person is the primary measure in the 2007 report used in the ranking of metropolitan areas reported widely in the press. • In the previous reports a Travel Time Index (TTI) (the ratio of travel time in the peak period to travel time under free flow conditions) was used to rank cities.

  5. Methodology (cont’d) • Methodology in the TTI reports has constantly changed over time; 2007 report changes include • Freeway speed estimate under congested conditions • Population estimates • Truck percentages for each road • Average of daily fuel prices • The revised speed estimation procedure used in 2007 is based on average daily traffic and speed observations from 29 metropolitan regions, which resulted in the low speed threshold being raised from 20 mph to 35 mph (graphic shown on next slide) • New performance measures added over time; current report has eleven (11) performance measures

  6. Urban Mobility Report Speed Estimation Chart Archived data based freeway speeds and daily volumes from twenty nine (29) metropolitan regions UTMPS: TTI model used for estimating speed from daily traffic

  7. Limitations • The report estimates the average conditions across the entire metropolitan region • For our region the report estimates 50% of VMT occur during congested conditions and, based on national averages, that congested speeds on freeways are 43 mph and on arterials are 25 mph • The report does not provide any facility-, direction-, time- or location-specific information • Even though the methodology has improved over time and attempts to include the impacts of transit, HOV, demand management and some operational improvements, it still cannot estimate performance on a specific corridor

  8. TPB’s Congestion Monitoring Program - Freeways • TPB has had a freeway and arterial highway congestion monitoring program since the 80’s • The freeway program represents a comprehensive study of the entire freeway system for am and pm peak periods and identifies congestion by location, time, and intensity (including the top ten congested locations). Aerial photography has been employed since 1993 on a three year cycle • The Impact of fixing bottlenecks such as the Wilson Bridge and the exit ramp to the Dulles Toll Road from the Capital Beltway can be studied, as shown on the next slide

  9. I-495/95 Capital Beltway (Outer Loop) Morning 2005 Traffic Survey Note: Number of lanes increased from 1 to 2 on the exit ramp from SB I-495 to WB VA 267

  10. TPB’s Congestion Monitoring Program - Arterials • Since 1999 a sample of arterial highways in the National Highway System has been monitored on a three year cycle • Use of global positioning system (GPS) technology provides speed information every two seconds along the roads being studied and helps identify bottlenecks (next slide shows the results of the arterial survey along VA 7) • The impacts of a signal optimization along certain corridors are noticeable in the survey, as are improvements carried out at bottleneck locations such as addition of turn lanes

  11. C C C C C B E D D D E E E E E F C D D C C D D D E E D E D C B C B C B Virginia Route 7 (Tour 1) Between Van Dorn Street and International Drive LOS for PM Period N FY 07 FY 01 FY 01 FY 04 FY 07 FY 04 FY 01 FY 07 FY 04 FY 01 FY 07 FY 04 International Dr D C C C C B B Haycock Rd NB Bottleneck Southbound E D F E E E C Washington St E F SB Bottleneck C D C D C Sleepy Hollow D D E D C D C Carlin Springs C E E E D D D Northbound Beauregard C C D B C B B Van Dorn Segment Length: 9.1 miles Peak hour: 5:00 – 6:00 pm Peak period: 4:00 – 7:00 pm PM Peak Period PM Peak Hour PM Peak Hour PM Peak Period

  12. TPB’s Congestion Management Process • The Congestion Management Process (CMP) is a requirement in metropolitan transportation planning under SAFETEA-LU • The CMP under development involves efforts to evaluate transportation system performance; define, analyze, implement, and assess strategies; and compile project-specific congestion management information

  13. Conclusions • Even though the methodology in the TTI report has improved over time, it still provides the average conditions across a region and is not a substitute for a regional congestion monitoring program which can identify location, direction, and time specific problem areas • The primary value of the report is not so much in the rankings but in studying how urban areas across the country are doing over time • In regions wheregrowth in demand has outpaced growth in supply by 45% or greater (like the Washington region), congestion has grown more than 300% • In regions where this disparity is less than 15%, congestion has grown less than 100%

  14. Conclusions (cont’d) • Congestion is a growing problem in urban areas of all sizes across the country • Traditional federal and state funding sources such as the gasoline tax have not kept pace with needs, and much of the responsibility for adding capacity has shifted to local funding sources and tolls

  15. Conclusions (cont’d) • The report lists examples of solutions to reduce congestion: manage the existing system better, add capacity in critical corridors, relieve choke points, change usage patterns, provide travel choices, diversify development patterns, and adopt realistic expectations. • TTI estimated the economic impact of reducing congestion in 8 congested Texas urban areas and concluded that spending $ 65 billion in strategies will yield a total economic benefit of $ 540 billion

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