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Travel Time Reliability:
Making It There On Time, All The Time

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prepared for

Federal Highway Administration

prepared by

Texas Transportation Institute


Cambridge Systems, Inc.


January 1, 2006

Table of Contents

What Is Travel Time Reliability?
Why is travel time reliability important?
What measures are used to quantify travel time reliability?
What are the steps for developing travel time reliability measures?
Case studies illustrating steps to calculate reliability measures
Who is using reliability measures?
For additional information

List of Tables

Table 1. Characteristics of Freight-significant Corridors
Table 2. Operating Characteristics of the Ambassador Bridge Crossing
Table 3. Value of Infrastructure at Morning Peak Travel Times, 2030

List of Figures

Figure 1. Averages Do Not Tell the Full Story
Figure 2. Commuters Plan Trips Based on the Worst Days, Not the Average Day
Figure 3. Reliability Measures Capture the Benefits of Traffic Management
Figure 4. Reliability Measures Are Related to Average Congestion Measures
Figure 5. Reliability Measures Are Easy to Calculate with Continuous Data
Figure 6. A Methodical Approach Can Be Used to Produce Travel Time Reliability Measures
Figure 7. Establish Who Will Use Reliability Measures and How They Will Use Them
Figure 8. A Reliability Measure Is Included in FHWA's Monthly Congestion Dashboard Report
Figure 9. WSDOT Travel Time Mobility and Reliability Corridor Data
Figure 10. WSDOT Commuter Reliability Information

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