Abstract
This study investigated the effects of local and
frequently updated information about adverse weather and
road conditions on driver behaviour. The information was
transmitted by several types of variable message signs
(VMS). Two evaluations investigated the effects of VMS
systems involving an individual sign or two signs; two
other evaluations focused on more extensive VMS systems
involving several signs, and two evaluations studied the
effects of the sign technology. The slippery road
condition sign and minimum headway sign decreased the
mean speed of cars travelling in free-flow traffic by 1-2
km/h. The minimum headway sign also decreased the
proportion of short headways. In addition, drivers'
reports suggested that these variable message signs have
other effects on driver behaviour, such as the refocusing
of attention to seek cues on potential hazards, testing
the slipperiness of the road, and more careful passing
behaviour. Lowering the speed limit from 100 km/h to 80
km/h on a weather-controlled road decreased the mean
speed by an average of 3.4 km/h in winter. The system
proved most effective when adverse weather and road
conditions were not easy to detect. The system also
decreased the standard deviation of speed. Most drivers
accepted lowered speed limits and found variable speed
limits useful. Variable speed limit signs using
fibre-optic technology were found to be more effective
than electromechanical signs. However, effective signs
may divert the driver's attention from adjacent fixed
signing. The slippery road condition sign is recommended
for careful use at critical spots, whereas a system
including variable speed limits is recommended for
somewhat longer road sections. The use of fibre-optic
signs is recommended for weather-controlled applications.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 2 Nov 2001 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-5871-5 |
Electronic ISBNs | 951-38-5872-3 |
Publication status | Published - 2001 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- traffic signs
- speed limit
- variable message signs
- VMS
- cold weather
- driver behavior
- road condition
- slippery
- evaluation
- information systems
- winter
- road surface
- ice
- traffic safety