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245 A p p e n d i x F Two sets of statistical comparisons were made regarding the end of congestion. One was made assuming a normal distribution. The other was made using the Andersonâ Darling K-sample test, a nonparametric test that allows a comparison of two populations with skewed distributions (1, pp. 918â924). Tables F.1 through F.3 show the results for the a.m. and p.m. periods. The boldface numbers in the tables indicate statistically significant differences at the 95% con- fidence level, and italic numbers indicate statistically signifi- cant differences at the 90% confidence level. The results are generally very similar, with many of the observed differ- ences easily attributable to how these two types of tests treat the importance of outliers given the total number of data points in the samples being tested. Statistics Related to the End of Congestion: Seattle Analysis Table F.1. p-Values for Comparing Ending Times of Congestion Under Disruptive Versus Nondisruptive Conditions Route A.M. Peak Period P.M. Peak Period Crash Influenced Incident Influenced Either Crash or Incident Influenced Crash Influenced Incident Influenced Either Crash or Incident Influenced I-405 Bellevue northbound 0.00 0.00 0.00 0.00 0.40 0.01 I-405 Bellevue southbound 0.00 0.00 0.00 0.03 0.20 0.11 I-405 Eastgate northbound 0.01 0.21 0.03 0.00 0.47 0.02 I-405 Eastgate southbound 0.01 0.20 0.01 0.03 0.49 0.11 I-405 Kennydale northbound 0.00 0.16 0.00 0.01 0.25 0.01 I-405 Kennydale southbound 0.00 (0.06) 0.00 0.63 0.32 0.60 I-405 Kirkland northbound 0.68 0.00 0.01 (0.07) 0.62 0.04 I-405 Kirkland southbound 0.02 0.01 0.03 0.00 0.00 0.00 I-405 North northbound 0.00 0.03 0.00 0.00 0.55 0.01 I-405 North southbound 0.00 0.00 0.00 0.00 0.44 0.01 I-405 South northbound 0.00 0.02 0.00 0.11 0.34 0.24 I-405 South southbound 0.01 0.01 0.00 0.48 0.32 0.43 I-5 Everett northbound 0.00 0.61 0.00 0.00 0.01 0.00 I-5 Everett southbound 0.00 0.38 0.00 0.00 0.00 0.00 I-5 Lynnwood northbound 0.45 0.69 0.70 0.21 0.19 0.12 (continued on next page)
246 I-5 Lynnwood southbound 0.01 0.01 0.01 0.00 0.21 0.00 I-5 North King northbound 0.69 0.51 0.77 (0.09) 0.54 0.13 I-5 North King southbound 0.03 0.02 0.04 0.00 (0.06) 0.00 I-5 Seattle CBD northbound 0.55 0.51 0.00 0.42 0.54 0.00 I-5 Seattle CBD southbound 0.00 0.48 0.00 0.55 0.50 0.54 I-5 Seattle North northbound 0.55 0.51 0.00 0.42 0.54 0.00 I-5 Seattle North southbound 0.00 0.24 0.00 0.01 0.11 (0.06) I-5 South northbound (0.08) 0.49 0.30 0.00 NA 0.00 I-5 South southbound 0.05 0.04 (0.05) 0.15 0.40 0.25 I-5 Tukwila northbound (0.10) 0.24 0.23 0.00 0.00 0.00 I-5 Tukwila southbound 0.00 0.55 0.00 0.00 0.01 0.00 I-90 Bellevue eastbound 0.69 0.69 0.85 0.01 0.16 0.02 I-90 Bellevue westbound 0.29 (0.06) (0.07) 0.00 0.00 0.00 I-90 Bridge eastbound 0.00 0.00 0.00 0.00 0.01 0.00 I-90 Bridge westbound 0.00 0.02 0.00 0.02 0.00 0.00 I-90 Issaquah eastbound 0.69 0.69 0.85 0.66 0.29 0.60 I-90 Issaquah westbound 0.00 0.51 0.00 NA NA NA I-90 Seattle eastbound 0.00 0.37 0.00 (0.10) 0.35 0.17 I-90 Seattle westbound 0.00 0.05 0.00 0.63 0.30 0.58 SR 167 Auburn northbound 0.17 0.41 0.31 0.41 0.46 0.53 SR 167 Auburn southbound 0.00 0.00 0.00 (0.10) 0.39 0.23 SR 167 Renton northbound 0.00 0.00 0.00 0.00 0.04 0.00 SR 167 Renton southbound 0.00 0.00 0.00 0.16 0.20 0.12 SR 520 Redmond eastbound 0.46 0.65 0.69 0.44 0.63 0.67 SR 520 Redmond westbound 0.00 0.00 0.00 0.00 0.00 0.00 SR 520 Seattle eastbound 0.00 0.00 0.00 0.01 0.25 0.02 SR 520 Seattle westbound 0.00 0.12 0.00 0.05 0.53 0.11 Note: CBD = central business district. Table F.1. p-Values for Comparing Ending Times of Congestion Under Disruptive Versus Nondisruptive Conditions (continued) Route A.M. Peak Period P.M. Peak Period Crash Influenced Incident Influenced Either Crash or Incident Influenced Crash Influenced Incident Influenced Either Crash or Incident Influenced
247 Table F.2. Comparison of Ending Times of Congestion for A.M. Peak Period Route Nonevent End of Congestion Time Added Time if Incident Occurs Added Time if Crash Occurs Z Score for Incident Comparison Z Score for Crash Comparison I-405 Kennydale northbounda 11:47 0:34 1:33 1.265 3.368 I-405 North southbound 9:56 1:27 2:09 2.209 3.101 I-5 North King southbounda 11:06 0:48 1:29 2.472 3.321 I-5 Seattle CBD northbound 12:15 (0:42) 1:20 NAb NAb I-405 Kirkland southbound 10:16 0:56 1:14 2.590 2.732 SR 520 Seattle eastbound 11:54 6:02 6:53 4.820 5.752 I-5 Lynnwood southbound 10:06 1:57 1:39 3.048 2.659 I-5 South northbound 9:16 0:12 0:22 1.204 2.344 SR 167 Auburn northbounda 11:40 0:51 0:59 1.318 1.576 I-405 Eastgate northbounda 11:38 0:16 1:04 1.100 2.368 I-5 Seattle North southbound 9:38 1:10 4:58 2.650 7.531 I-405 Kennydale southboundc 9:08 1:19 1:23 1.674 2.083 I-405 South southboundc 12:46 3:12 2:17 3.171 2.782 SR 167 Renton northboundc 9:13 1:47 1:22 2.765 2.513 SR 520 Seattle westbounda 9:51 0:47 2:54 1.694 3.412 I-5 Tukwila northbound 10:06 0:14 0:32 1.103 1.778 I-90 Issaquah westbound 9:10 0:09 0:33 0.521 4.616 I-90 Bellevue westbound 9:26 0:13 (0:06) 1.607 -0.781 I-405 Bellevue northbounda 11:01 3:34 5:00 5.252 7.928 I-405 South northboundc 8:21 4:49 7:47 2.478 10.562 I-90 Seattle eastbound 8:45 0:05 1:05 0.317 5.102 I-90 Seattle westbound 7:35 0:42 1:52 1.238 8.146 I-90 Bridge eastbound 9:23 0:45 1:04 3.806 5.876 I-405 Bellevue southbounda 8:27 7:56 11:07 8.517 27.434 I-5 Everett southbound 7:08 0:06 1:06 1.975 2.398 I-90 Bridge westbound 8:04 0:26 1:30 2.048 3.518 I-5 Seattle CBD southbound 9:28 1:04 4:57 2.387 8.190 SR 167 Auburn southbound 8:58 7:29 9:59 8.068 30.022 I-405 Eastgate southbound 7:22 0:07 0:32 1.294 5.227 (continued on next page)
248 SR 167 Renton southbound 9:42 7:33 7:30 7.033 4.957 I-5 Tukwila southbound 7:08 0:05 7:51 0.719 1.026 SR 520 Redmond westbound 7:09 0:56 2:10 2.266 2.888 I-405 North northbound 7:56 0:12 1:47 1.882 1.562 I-5 Everett northbound 7:05 0:01 0:14 1.202 1.928 I-5 Lynnwood northbound 7:13 (0:01) 0:20 (0.403) 0.709 I-5 Seattle North northbound 7:07 0:04 (0:02) 1.332 NAd I-90 Bellevue eastbound 7:05 (0:00) (0:00) (1.380) NAd I-5 South southbound 7:07 0:08 (0:00) 1.047 (0.204) I-405 Kirkland northbound 7:05 0:05 (0:00) 1.882 (1.686) SR 520 Redmond eastbound 7:05 (0:00) (0:00) (0.267) (2.015) I-90 Issaquah eastbound 7:05 (0:00) (0:00) (1.381) NAd I-5 North King northbound 7:05 (0:00) (0:00) (1.324) (1.324) a Uses a 10% travel time increase as the point at which congestion has abated rather than the 5% norm. b Too few nondisrupted days occurred to compute a test statistic. c Uses a 20% travel time increase as the point at which congestion has abated rather than the 5% norm. d Too few crash days occurred to compute a test statistic. Table F.2. Comparison of Ending Times of Congestion for A.M. Peak Period (continued) Route Nonevent End of Congestion Time Added Time if Incident Occurs Added Time if Crash Occurs Z Score for Incident Comparison Z Score for Crash Comparison Table F.3. Comparison of Ending Times of Congestion for P.M. Peak Period Nonevent End of Congestion Time Added Time if Incident Occurs Added Time if Crash Occurs Z Score for Incident Comparison Z Score for Crash Comparison I-405 Bellevue northbound 18:09 0:07 0:27 1.264 3.927 I-405 Bellevue southbound 19:44 0:13 0:20 1.943 2.629 I-405 Eastgate northbound 16:24 0:05 0:47 0.351 2.221 I-405 Eastgate southbound 19:12 0:00 0:15 0.064 2.377 I-405 Kennydale northbound 18:05 0:17 0:23 2.323 2.006 I-405 Kennydale southbound 19:27 (0:01) 0:00 (0.195) 0.137 I-405 Kirkland northbound 19:03 0:01 0:11 0.246 2.196 I-405 Kirkland southbound 16:55 1:00 1:21 4.686 4.849 I-405 North northbound 19:18 (0:05) 0:14 (0.799) 3.236 I-405 North southbound 17:40 (0:11) 0:46 (0.919) 3.611 I-405 South northbound 20:41 0:21 0:17 0.940 1.698 I-405 South southbound 19:36 (0:03) 0:05 (0.336) 0.776 I-5 Everett northbound 17:08 0:28 0:58 2.174 4.216 I-5 Everett southbound 16:35 0:24 0:57 2.979 4.441 I-5 Lynnwood northbound 19:00 0:08 (0:07) 1.320 (1.082) I-5 Lynnwood southbound 17:21 0:12 1:09 0.922 7.154 I-5 North King northbound 18:55 0:04 0:12 0.741 2.092 I-5 North King southbound 16:47 0:29 1:57 2.424 6.575 I-5 Seattle CBD northbound 18:53 (0:06) 0:13 (0.490) 1.020 (continued on next page)
249 I-5 Seattle CBD southbound 18:49 0:06 0:13 0.271 0.520 I-5 Seattle North northbound 18:34 0:05 0:07 0.726 1.093 I-5 Seattle North southbound 18:20 0:16 0:31 1.513 2.481 I-5 South northbound 16:05 0:00 0:45 0.000 1.914 I-5 South southbound 18:08 0:09 0:19 1.179 2.168 I-5 Tukwila northbound 16:23 0:23 1:56 2.329 5.897 I-5 Tukwila southbound 17:18 0:21 0:51 2.083 4.972 I-90 Bellevue eastbound 16:35 0:21 1:02 1.131 1.433 I-90 Bellevue westbound 16:13 1:21 2:10 2.078 8.804 I-90 Bridge eastbound 18:18 0:22 0:35 3.196 4.751 I-90 Bridge westbound 18:25 0:34 0:48 2.921 4.299 I-90 Issaquah eastbound 16:10 (0:05) (0:05) (2.858) NAa I-90 Issaquah westbound 16:05 0:00 0:00 0.000 0.000 I-90 Seattle eastbound 17:07 (1:02) 1:05 NAb 6.457 I-90 Seattle westbound 17:29 0:19 0:07 1.274 0.219 SR 167 Auburn northbound 17:31 (0:08) (0:31) (0.641) NAa SR 167 Auburn southbound 18:47 0:08 0:08 1.799 2.716 SR 167 Renton northbound 17:22 0:27 0:57 1.973 4.550 SR 167 Renton southbound 18:47 0:08 0:16 1.293 2.853 SR 520 Redmond eastbound 19:09 0:05 (0:07) 0.835 (0.841) SR 520 Redmond westbound 16:51 1:24 1:53 2.652 7.432 SR 520 Seattle eastbound 18:52 0:11 0:22 1.654 3.232 SR 520 Seattle westbound 20:00 (0:01) 0:12 (0.206) 1.727 a Too few crash days occurred to compute a test statistic. b Too few incident days occurred to compute a test statistic. Table F.3. Comparison of Ending Times of Congestion for P.M. Peak Period (continued) Nonevent End of Congestion Time Added Time if Incident Occurs Added Time if Crash Occurs Z Score for Incident Comparison Z Score for Crash Comparison Reference 1. Scholz, F. W., and M. A. Stephens. K-Sample AndersonâDarling Tests. Journal of the American Statistical Association, Vol. 82, No. 399, 1987, pp. 918â924. www.jstor.org/discover/10.2307/2288805?uid= 3739960&uid=2&uid=4&uid=3739256&sid=21101238038017.
