TCC and STC project helps increase intersection safety for MODOT
TEMPE, AZ - 01/10/2013 - Missouri DOT (MODOT) recognized a problem
intersection at Pink Hill Road and Missouri Hwy H in Oak Grove, MO.
Driving northbound on Hwy H the roadway climbs from a low area up a hill to
the intersection. Because of the grade of the hill, vehicles wishing to
cross Hwy H or turn onto it from Pink Hill cannot see easily see the
approaching cars on Hwy H thus creating a traffic hazard for motorists on
Previously the intersection had a continuous four-way flasher on a span wire
across the intersection. While this provided a warning to motorists, it was
not interactive. MODOT approached Traffic Control Corporation (TCC)
regarding the design of a sensor based system for improving the beacon
operation for vehicles crossing or turning from Pink Hill Rd as well as
vehicles traveling northbound on Hwy H.
The location proved challenging in that there was AC power available at some
points but not at all of the points where beacons were needed. STC worked
with TCC, an Econolite distributor, and MODOT to come up with a solution for
the intersection. The new configuration included a three point approach.
The main control point is an AC powered point, serves as the system master,
includes video detection and an AC flasher circuit for one direction of
travel on Pink Hill. Nearby the second point is a solar powered slave
flashing beacon facing the opposite direction of traffic on Pink Hill. The
third point, located in advance on northbound Hwy H, is both a flashing
beacon system and a detector station, is solar powered and serves as an
intersection advance flasher.
TCC and MODOT chose to employ an Autoscope video detection system at the
Pink Hill Rd stop bars to detect when traffic was present. STC furnished a
custom AC powered master system for the intersection based on the Solar
Ped-X control package normally used for crosswalks. The enclosure
included a two-channel Autoscope video detection system, an Autoscope camera
power/signal interface board and a color flat screen monitor as well as
connection for AC power and distribution within the enclosure.
The STC equipment included a Solar Ped-X control circuit with a NEMA flasher
module to drive a beacon at the intersection. When a vehicle is detected
at either stop bar a call is input to the Solar Ped-X controls. When the
control logic responds to the call, a run time value is transmitted to the
intersection advance flasher to warn motorists heading northbound that
vehicles are present at the Pink Hill crossing.
The intersection advance unit employs an RTMS G4 sensor to detect vehicles
traveling northbound on Hwy H. When a detection occurs a pending call is
generated in the local Solar Ped-X control and detected by the master unit
at Pink Hill. When the call is serviced, the flashers at Pink Hill begin
flashing to warn motorist of approaching vehicles on Hwy H. The Solar Ped-X
system includes retriggerable timers so additional vehicle detections add to
the run time value.
The Solar Ped-X control package allows for two-way communications between
points via FHSS radio link. This combined with the solar power package
allowed the system to be installed more affordably and more timely than an
all AC system.
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