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Effects of Automated Speed Enforcement in Maryland Work Zones

Effects of Automated Speed Enforcement in Maryland Work Zones. Mark Franz University of Maryland Traffic Safety and Operations Lab. Agenda. Study Site Summaries Issues to be addressed General Analysis Procedure In depth analysis/plan of analysis for each issue Conclusions.

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Effects of Automated Speed Enforcement in Maryland Work Zones

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  1. Effects of Automated Speed Enforcement in Maryland Work Zones Mark Franz University of Maryland Traffic Safety and Operations Lab

  2. Agenda Study Site Summaries Issues to be addressed General Analysis Procedure In depth analysis/plan of analysis for each issue Conclusions Franz

  3. Study Site Summaries • For current data set, all sites have three data collection locations • Upstream • At ASE • Downstream • WB I695 @ Charles St.: • 3 Lanes • Posted Speed Limit (PSL) = 50 mph • Before Data: Middle lane only at ASE • During Data: Left Lane only at ASE • Before and During data collected on different days of week • SB I95/ETL: • 3 Lanes • PSL = 55 mph • Complete lane coverage, Before and During data collected on different days of week • NB I95 @ ICC: • 4 Lanes • PSL = 65 mph • Complete lane coverage, Before and During data collected on different days of week Franz

  4. Work Zone ASE Issues In all cases, future work will analyze lane by lane, classified speed bins, at four data collection locations • Does ASE reduce motorists’ speed? • Does ASE affect driver’s spatial speeding behavior? • Does ASE make work zones safer by reducing speed variation? (10 mph pace, 85% speed, mean speed) • Is there a residual effect on drivers speeding behavior after removal of ASE (Halo effect)? • Do drivers learn where ASE takes place and adjust speeding behavior accordingly? • Does the installment of ASE signs effect drivers speeding behavior? • Is there a time lag in the effect of ASE on regular road users? • Does moving the location of the ASE vehicle from day to day have an effect on drivers’ speeding behavior? Franz

  5. General Analysis Procedure • 3 Speed bins: • Conservative Drivers (at or below PSL) • Normal Drivers (PSL +1 mph – PSL +10 mph) • Aggressive Drivers (more than 10 mph over PSL) • Compare percentage of motorists in each speed. • Temporal Considerations: Before vs. During Deployment • Spatial Considerations: Upstream vs. At ASE and At ASE vs. Downstream Franz

  6. 1. Does ASE reduce motorists’ speed? Input Data: Time stamped, speed bin data, before and during deployment on , lane separated, classified data, collected on the same days of the week Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Create Driver Type Speed Bins Statistical Test Results Hypothesis: Motorists reduce speed during ASE deployment. Franz

  7. Speed Distribution Stability Some data collection locations show variability in the daily distribution of speeds. For these locations, more data needs to be collected. Franz

  8. Results: Does ASE reduce motorists’ speed? (Before Data: Middle Lane, During Data: Left Lane) 64.8 mph 67.3mph 55.1 mph 54.5 mph 37.8 mph 42.5mph Statistical test results: No significant differences Franz

  9. Results: Does ASE reduce motorists’ speed? 69.1 mph 68.8mph 60.2 mph 59.7 mph 50.9 mph 50.2mph Indicates a significant change in motorist percentage Statistical test results: Reduction in aggressive motorists during ASE deployment Franz

  10. Results: Does ASE reduce motorists’ speed? 79.0 mph 79.9mph 69.6 mph 69.4 mph 58.9 mph 56.0 mph Statistical test results: Reduction in normal motorists during ASE deployment Franz

  11. Summary: Does ASE reduce motorists’ speed? No significant changes at I695 @ Charles St. (before data: middle lane, during data: left lane) Reduction in aggressive motorists at I95/ETL during ASE deployment Reduction in normal motorists at I95 @ ICC during ASE deployment Franz

  12. 2. Does ASE affect motorists’ spatial speeding behavior? Input Data: Time stamped, speed binned, lane separated , classified data, upstream, at, downstream, and far downstream of ASE Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Create Driver Type Speed Bins Statistical Test Results Hypothesis: Motorists will slow down as they approach ASE, then speed back up downstream. Franz

  13. Results: Does ASE affect driver’s spatial speeding behavior? (At ASE: Before Data: Middle Lane, During Data: Left Lane) Middle Lane Left Lane Statistical test results: During deployment the speeding pattern is generally more stable, and upstream aggressive driving is reduced Franz

  14. Results: Does ASE affect driver’s spatial speeding behavior? (At ASE: Before Data: Middle Lane, During Data: Left Lane) 64.2 mph 64.8 mph 67.5 mph 65.7 mph 55.1 mph 54.5 mph 55.0 mph 55.5mph 37.8 mph 42.5 mph 42.0mph 30.6 mph Middle Lane Middle Lane Left Lane Left Lane Statistical test results: During deployment, downstream aggressive driving is reduced Franz

  15. Results: Does ASE affect driver’s spatial speeding behavior? 69.0 mph 68.7 mph 68.8 mph 69.1 mph 59.9 mph 59.7 mph 59.9 mph 60.2 mph 48.5 mph 50.2mph 47.2 mph 50.9 mph Statistical test results: During deployment, aggressive driving is reduced while approaching ASE and speeding pattern becomes stable Franz

  16. Results: Does ASE affect driver’s spatial speeding behavior? 68.8 mph 68.9 mph 69.1 mph 69.1 mph 59.7 mph 59.6 mph 60.2 mph 60.1 mph 50.2 mph 50.3mph 50.8 mph 50.9 mph Statistical test results: No significant differences, speeding pattern is stable before and during ASE deployment Franz

  17. Results: Does ASE affect driver’s spatial speeding behavior? 79.2 mph 79.0 mph 79.2mph 79.9mph 69.6 mph 69.4 mph 69.6 mph 69.7 mph 53.1 mph 56.0mph 59.2 mph 58.9 mph Statistical test results: During deployment the speeding pattern is generally more stable Franz

  18. Results: Does ASE affect driver’s spatial speeding behavior? 79.0 mph 79.9mph 81.6mph 79.4mph 69.4 mph 69.5 mph 69.6 mph 70.2 mph 56.0 mph 58.9 mph 57.2 mph 59.6 mph Statistical test results: During deployment the speeding pattern is generally more stable Franz

  19. Summary: Does ASE affect driver’s spatial speeding behavior? ASE makes the spatial speeding behavior of motorists generally more stable, thus making the work zones safer At I695 @ Charles St., aggressive drivers seemed to be effected upstream and downstream of the ASE location At I95/ETL, aggressive are effected while approaching the ASE location At I95 @ ICC, the speeding pattern becomes more stable Franz

  20. 3. Does ASE make work zones safer by reducing speed variation? Input Data: Time stamped, speed bin data, before and during deployment, upstream, at ASE, downstream, and far downstream on same days of week Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Calculate average frequency in each bin Compute 10 mph pace Compare before vs during Hypothesis: ASE reduces speed variation as well as the mean, and 85 percentile speed. Franz

  21. Results: Does ASE make work zones safer? Franz

  22. Summary: Does ASE make work zones safer? • I695 @ Charles St.: • Decrease percentage of motorist in 10 mph pace • Increase in mean speed • Increase in 85 percentile speed • Increase in aggressive motorists and in aggressive motorists’ speed • I95/ETL: • Increase percentage of motorist in 10 mph pace • Decrease in mean speed • Decrease in 85 percentile speed • Decrease in aggressive motorists and in aggressive motorists’ speed • I95 @ ICC: • Slight decrease in mean speed • Other parameters show little change Franz

  23. 4. Is there a residual effect on drivers speeding behavior after removal of ASE (Halo effect)? Input Data: Time stamped, speed binned, lane separated , classified data, during and after ASE deployment Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Create Driver Type Speed Bins Statistical Test Results Hypothesis: Motorists will return to pre-ASE speeding behaviors when ASE is removed. Franz

  24. 5. Do drivers learn where ASE takes place and adjust speeding behavior accordingly? Input Data: Time stamped, speed bin data, and LPR data Up, At ASE, downstream, and far downstream For 2-3 consecutive weeks during deployment Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Create Driver Type Speed Bins Statistical Test Results Hypothesis: Regular road users learn where ASE takes place and adjust speeding behavior accordingly. Franz

  25. 6. Does the installment of ASE signs effect drivers speeding behavior? Input Data: Time stamped, speed bin data, Upstream, at ASE, downstream, before and during sign installment Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Create Driver Type Speed Bins Statistical Test Results • Hypothesis: ASE warning signs will not reduce motorists’ speed. Franz

  26. 7. Is there a time lag in the effect of ASE on regular road users? Input Data: Time stamped, speed bin data, Upstream, at ASE, downstream and far downstream, for 4 weeks during ASE deployment pair with LPR data Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Create Driver Type Speed Bins Statistical Test Results • Hypothesis: After 3 weeks (delivery of citations), a reduction in aggressive drivers is expected. Franz

  27. 8. Does moving the location of the ASE vehicle from day to day have an effect on drivers’ speeding behavior? Input Data: Time stamped, speed bin data, Upstream, at ASE, downstream, and far downstream for 3 weeks during ASE deployment Define AM, PM and Off Peak Periods Check for Speed Distribution Stability Create Driver Type Speed Bins Statistical Test Results • Hypothesis: Moving the ASE vehicle will reduce speeds through the work zone, and reduce the learning of regular motorist Franz

  28. Conclusions • I695 @ Charles St.: • ASE did not reduce speeds at ASE • ASE did reduce speeds up and downstream • Did not reduce speed variation • Need complete lane coverage, and data collection on same days of week • I95/ETL: • Reduction aggressive drivers at ASE • Reduction in speed variation and mean speed • Need data collection on same days of week for more conclusive results • I95 @ ICC: • Reduction in mean speed • More stable speeds though work zone • Need data collection on same days of week for more conclusive results • Stage 2 is expected to give more definitive results and more in depth spatial analysis Franz

  29. Questions/Comments Mark Franz Email: mfranz1@umd.edu Phone: 301-405-2638 Franz

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