26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 1 EXAMPLES OF EVALUATIONS > Aim of the systems/services  improved traffic safety and fluency under poor weather and road conditions > Aims of the evaluation  impacts on driver behaviour -> safety  development of the system/service

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 2 Evaluation of a traffic information system Imple- mentation Driver -perception -comprehension knowledge -acceptance Driver -perception -comprehension knowledge -acceptance Driver behaviour -speed -headways Driver behaviour -speed -headways Traffic Safety Traffic Safety Reliability observations Process ev. Driver interviews Behaviour observation Statistics Data collection DEVELOPMENTIMPACTS

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 3 Four studies > Study 1: Road weather report > Study 2: Slippery road condition signs > Study 3: Weather controlled speed limits and warnings: motorway > Study 4: Weather controlled speed limits and warnings: single-carriageway

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 4  Purpose For each Study:  main results  implications

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 5 Study 1: Road weather report Purpose > Regional classification  normal-poor-warning > Evaluation  drivers opinions/acceptance  service providers opinions, development ideas, co-operation  reliability of service

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 6 Study 1: Road weather report Main results > Service was well known 87% (content by 54%) > potential effects on behaviour  time reserved, 63%  driving behaviour, 71%  choice of departure time, 51%  time to change winter tyres, 53% > reliability, subjective estimate: 90% correctly > 6 peak days - variable success in predictions > co-operation improved

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 7 Study 1: Road weather report Implications > Modifications to the service  terminology  more details in information, more descriptions  need to general information of the service  lowered threshold to warnings  longer forecasts  more consistency > Decision to develop for pedestrians

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 8 Study 2: Slippery road condition signs Purpose > To warn about local slipperiness > Evaluation  effects on driver behaviour (speed, headways, potential other effects)  driver opinions and reported potential effects  operator opinions

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 9 Study 2: Slippery road condition sign Main results > Slippery road condition sign  decrease of mean speed on slippery roads 1-2 km/h  not effective on all sites in the experiment > Minimum headway recommendation sign  decrease of mean speed 1 km/h  decrease of proportion of short headways (less than 1.5 sec), -34% > Several other effects on reported driver behaviour  refocusing attention, testing the slipperiness, more careful passing

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 10 Study 2: Slippery road condition sign Implications > Slippery road condition signs improved traffic safety by decreasing mean speed, increasing driving distances. > Most of the reported effects are assessed positive in terms of safety > Automatic data collection (RWS, CCTV) is important for the manual control > Flashing messages not recommended? > The minimum headway sign is suggested to develop further > Careful use of the slippery road condition sign at specific sites is recommended

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 11 Study 3: Weather controlled speed limits and warnings: motorway Purpose > Local speed management and warning system  traffic safety > Evaluation  effects on driver behaviour  driver acceptance  system reliability

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 12 Study 3: Weather controlled speed limits and warnings: motorway Main results VMSEffects Mean speedSt.dev. 100 km/h  80 km/h– 3.4 km/h– 3.4 km/h - slipperiness difficult to detect– 5.4 km/h 100 km/h  80 km/h+slipp.– 1.7 km/h– 120 km/h  100 km/h– 5.1 km/h– 2.1 km/h

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 13 Study 4: Weather controlled speed limits and warnings: single-carriageway Purpose > Variable speed limits and local warnings  traffic safety and fluency > Evaluation  effects on driver behaviour  driver acceptance  system reliability

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 14 Study 4: Weather controlled speed limits and warnings: single-carriageway Main results VMSEffects Mean speedShort HWs 80 km/h+slipp.– 2.5 km/h– 25% 80 km/h+ 1 km/h– 10% 100 km/h(poor+ 7.3 km/h) (normal+ 5.4 km/h+ 31)% good+ 3.9 km/h

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 15 MotorwaySingle-carriageway (1995)(1998) recall/speed limit 88–94% 95% speed limits approved81%61–81% recall/warning sign66%73% recall/text message34%47% system necessary 95%96% control principles93%70% - dynamic control-56% Studies 3 and 4: Weather controlled speed limits and warnings Driver interviews

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 16 MotorwaySingle-carriageway (1995)(1998) ‘Correct’ speed limits under poor/normal 72%76% and 60% conditions Studies 3 and 4: Weather controlled speed limits and warnings Reliability

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 17 Study 3: Weather controlled speed limits and warnings: motorway Implications > Variable speed limits improved traffic safety by decreasing mean speed and standard deviation of speed > Slippery road sign decreased mean speed but did not affect standard deviation of speed > In winter the system was most effective when the slipperiness was not easily detectable > The system proved to be effective also in summer > Drives accepted the system > The results encouraged to continue the development of the system (control principles, single-carriageway )

26 Sep 2000Communities and Infrastructure – Pirkko Rämä# 18 Study 4: Weather controlled speed limits and warnings: single-carriageway Implications > The system improved fluency by increasing mean speed under good conditions in winter > The use of variable speed limits calls for a sophisticated control system. Inadequate use of speed limits reduce traffic safety by increasing mean speed excessively. > Traffic safety was improved in adverse road conditions by decreasing mean speed and the proportion of short headways between vehicles. More use of the lowest limit. > Drivers accept the variable speed limits and rely on the system > More information of the control principles to drivers