Research Article
Forecasting Travel Speed in the Rainfall Days to Develop Suitable Variable Speed Limits Control Strategy for Less Driving Risk
Table 4
Expressway risk coefficient with different speed limit methods under different rainfall intensities.
| | Expressway risk coefficient | Rainfall intensity | Time | Speed limit method | | Static 85th percentile speed | Variable 85th percentile speed | Variable 90th percentile speed |
| | R | Light | 6.26 10 : 00 | 10.08 | 6.50 (−35.52%) | 6.83 (−32.24%) | | 7.3 01 : 00 | 6.58 | 6.70 (+1.82%) | 7.04 (+7.00%) | | 7.4 10 : 00 | 9.26 | 6.51 (−29.70%) | 6.88 (−25.70%) | | Moderate | 6.26 09 : 00 | 11.96 | 6.39 (−46.57%) | 6.72 (−43.81%) | | 7.3 12 : 00 | 8.27 | 6.60 (−20.19%) | 6.94 (−16.08%) | | 7.4 09 : 00 | 11.80 | 6.40 (−45.76%) | 6.72 (−43.05%) | | Heavy | 7.3 06 : 00 | 11.97 | 6.39 (−46.62%) | 6.71 (−43.94%) | | 7.3 16 : 00 | 10.42 | 6.48 (−37.81%) | 6.81 (−34.64%) | | 7.4 13 : 00 | 11.40 | 6.42 (−43.68%) | 6.75 (−40.79%) | | Torrential | 7.3 14 : 00 | 9.59 | 6.53 (−31.91%) | 6.86 (−28.47%) | | 7.3 15 : 00 | 12.69 | 6.35 (−49.96%) | 6.67 (−47.44%) | | 7.4 04 : 00 | 12.94 | 6.33 (−51.82%) | 6.65 (−48.61%) |
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