Human factors indicate that too little stimulation can lead to driver inattention, which is a
contributor to crash frequency. Saskatchewan is characterised by long, straight, rural roads
with low driver workload. It is likely that low driver workload may be a factor in preventable
collisions at the junction of Provincial Highway 35 and Provincial Highway 16 (Yellowhead
Highway), which has experienced multiple fatal and injury collisions.
The purpose of this paper is to discuss the implementation and current operation of the radar
activated LED Stop signs at the junction of Provincial Highway 35 and Provincial Highway 16,
which were installed by the Saskatchewan Ministry of Highways and Infrastructure (SMHI) in
2012 to mitigate a trend in right angle collisions. The existing traditional intersection
improvements included illumination, Stop Ahead signs, dual oversize Stop signs equipped with
red flashing beacons, and transverse pavement rumble strips.
Ten years of collision data indicated that the trend in right angle collisions was not affected by
the existing improvements, which were implemented over several years. The sight lines to this
intersection are unobstructed and the Stop signs with red flashing beacons are visible from
vehicles approaching several hundred metres away. When the Stop signs with the continuously
flashing beacons were replaced with the LED Stop signs, the beacons were reinstalled on the
intersection light standards so collision trends could be monitored without changing more than
one aspect of the intersection at a time. The radar-activated lights on the Stop sign operate
differently than continuous beacons in that they are only activated when vehicles approach the
intersection at a speed that suggests they will not be able to comfortably decelerate to stop
safely. Comfortable deceleration distances were calculated with sign mounted radar aimed at
the distance where drivers will have to “slam on brakes” in order to stop at the junction.
The pilot project duration is a minimum two years, after which SMHI hopes to determine
whether the LED Stop signs should be considered as a safety improvement at other locations
throughout the provincial network. The goals of the pilot project are to determine the reliability of
the system components, how much maintenance it requires, the cost to maintain the system,
and to determine the effects of the system on traffic.
