Incorporating Reliability Performance Measures into the Transportation Planning and Programming Processes: Technical Reference (2014) / Chapter Skim
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From page 126... ...
125 B TRENDS IN RELIABILITY The SHRP 2 L03 report, Analytical Procedures for Determining the Impacts of Reliability Mitigation Strategies, provides an illustrative example of the challenges in interpreting the varied results of a reliability analysis. The section, Trends in Reliability, is excerpted in this appendix.
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From page 128... ...
127 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Section/Reliability Measure Year 2006 2007 2008 SHRP Section I-285 Eastbound from GA 400 to I-75 TTI 1.359 1.481 1.380 Average TTI 9.322 10.162 9.469 95th Percentile TTI 12.548 13.150 12.493 Buffer Index 0.346 0.294 0.319 80th Percentile TTI 10.505 11.382 10.849 Skew Statistic 1.148 0.996 1.070 Daily VMT 584,487 588,442 572,211 SHRP Section I-285 Westbound from GA 400 to I-75 TTI 1.826 1.893 1.672 Average TTI 12.564 13.026 11.504 95th Percentile TTI 19.053 19.754 19.543 Buffer Index 0.517 0.516 0.699 80th Percentile TTI 15.632 16.140 14.699 Skew Statistic 1.202 1.043 1.779 Daily VMT 584,487 588,442 572,211 SHRP Section I-285 Eastbound from GA 400 to I-85 TTI 2.247 2.314 1.797 Average TTI 14.495 14.926 11.593 95th Percentile TTI 23.353 24.724 21.084 Buffer Index 0.611 0.656 0.819 80th Percentile TTI 19.336 19.945 15.256 Skew Statistic 1.285 1.248 2.347 Daily VMT 588,597 580,629 567,497 SHRP Section I-285 Westbound from GA 400 to I-85 TTI 1.621 1.681 1.511 Average TTI 10.424 10.809 9.713 95th Percentile TTI 13.740 13.707 12.612 Buffer Index 0.318 0.268 0.299 80th Percentile TTI 11.622 11.957 11.082 Skew Statistic 0.790 0.763 0.656 Daily VMT 588,597 580,629 567,497 TABLE B.1.
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From page 129... ...
128 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Section/Reliability Measure Year 2006 2007 2008 SHRP Section I-75 Northbound from Roswell Road to Barrett Parkway TTI 1.579 1.652 1.514 Average TTI 8.762 9.170 8.405 95th Percentile TTI 11.827 12.823 12.357 Buffer Index 0.350 0.398 0.470 80th Percentile TTI 10.206 10.560 9.656 Skew Statistic 1.513 1.348 1.586 Daily VMT 669,568 675,274 N/A SHRP Section I-75 Southbound from Roswell Road to Barrett Parkway TTI 1.809 1.872 1.614 Average TTI 9.785 10.129 8.730 95th Percentile TTI 13.835 14.301 12.791 Buffer Index 0.414 0.412 0.465 80th Percentile TTI 11.208 11.575 10.529 Skew Statistic 0.849 0.920 0.945 Daily VMT 669,568 675,274 N/A All Sections TTI 1.720 1.800 1.585 Average TTI 10.033 10.492 9.220 95th Percentile TTI 14.266 15.151 13.597 Buffer Index 0.399 0.428 0.451 80th Percentile TTI 11.874 12.400 10.989 Skew Statistic 1.186 1.196 1.308 Daily VMT 3,150,088 3,154,932 2,878,074 Daily VMT without I-75 (I-285 to Barrett Pkwy) 1,789,122 1,790,030 1,734,742 Source: Cambridge Systematics, Inc.
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From page 130... ...
129 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE Figure B.1 I-285 eastbound. GA 400 to I-85, Peak Period Source: Cambridge Systematics, Inc.
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From page 131... ...
130 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE skew statistic indicate there was more spread in the distribution, but the worst travel times (the 80th and 95th percentiles) were decreased.
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