Traffic Counter Comparison on 2 Lane Roadways Rubber Tube Temporary Counter Sites Vs Wire Loop Permanent Counter Sites
Rubber Tube Traffic Counter Gamma Type Counter from TimeMark Cost approximately $1000/device Discounts for quantity purchases. TimeMark Incorportated (800) FAX (503)
Rubber Tube Count Average Weekday Count Installed for 1-3 days (Tuesday-Thursday) to determine average weekday traffic. Average weekday traffic then adjusted to average yearly daily traffic by seasonal adjustment factors. Two tubes allow counter to determine direction, speed, and classify of traffic.
Wire Loop Traffic Counter Unicorn Type from Diamond Traffic Products Four wire loop option buried in asphalt Diamond Traffic Products PO Box Alder Street Oakridge Oregon (541) FAX (541)
Typical Permanent Site Cost $28,000 for 4 sites with software included. Constructed by tribal construction department with aid of electrician to set meter base and connect to local power grid.
Traffic Counter Loop Layout Four Loops allow counter to determine lane volumes, speed and length of vehicle.
Type Counter Layouts Studied Double Lane Rubber Tubes (two tubes 16’ spacing crossing entire road. IE both lanes) Single Lane Rubber Tubes (two tubes 16’ spacing each lane. IE anchored in center of road with PK type nails) Wire Loop Counter Sites (4 Detectors – 2 each Lane 16’ spacing between loops in lanes )
Typical Study Site Three Rubber Tube Counters and One Wire Loop Counter Important to note what tube is plugged in to the A/B axle port.
Study Site on Route 53
Good ?? Data Route 3 Rubber tubes cover both lanes of traffic. Axle A 94% used Axle B 88% used 3455 ADT
Bad Data (High Error Percent) Route 53 Rubber tubes cover both lanes of traffic. Axle A 69% used Axle B 88% used 4828 ADT
Percent Accepted Signals 2-Lane Tube Type Counters Rt 75 Rt 3 Rt 53
Route 75 Comparison 12/16/2004 Northbound Lane ADT50%85%CarsTrucksBig 2-lane lane Wire1089 Southbound Lane ADT50%85%CarsTrucksBig 2-lane lane Wire1076 Total Lanes ADT50%85%CarsTrucksBig 2-lane lane Wire
Route 3 Comparison Note Speed of Wire Counter ??? Also short vehicle length ??? 12/16/2004 Northbound Lane ADT50%85%CarsTrucksBig 2-lane lane Wire1608 Southbound Lane ADT50%85%CarsTrucksBig 2-lane lane Wire1825 Total Lanes ADT50%85%CarsTrucksBig 2-lane lane Wire
Wire Loop Traffic Counter Layout Note: 16 foot loop spacing, not 10 foot Corrected 1/6/05
Typical Speed Distribution (Good Day) Northbound Speed Distribution (Uphill) Southbound Speed Distribution (Downhill)
Typical Speed Distribution (Bad Day) Northbound Speed Distribution (Uphill) Note: Loss of contact of one 4:00 am due to poor electrical connection. Repaired on 1/6/05. One Loop (two wires) were not crimped to connector in cabinet by contractor. Southbound Speed Distribution (Downhill)
Route 53 Comparison Note: Low Counts on 2-lane rubber tube setup also high 85% speed on Southbound 2-lane setup 12/16/2004 Northbound Lane ADT50%85%CarsTrucksBig 2-lane lane Wire2768 Southbound Lane ADT50%85%CarsTrucksBig 2-lane lane Wire2851 Total Lanes ADT50%85%CarsTrucksBig 2-lane lane Wire
Note: Many counts in the +55 mph class due to echo of signal in tube? and/or high traffic volume and high % error signals for one tube. This is the one site that used “D” type tubing for counter. This tubing may be the cause of the high speeds and high error %.
2 Lane Study Site on Route 53 Red car (southbound) high 85% speed, Pickup truck (northbound) data better. Traffic counter located in left ditch nearest to red car.
Errors Found in First Year of Operation of Permanent Wire Loop Counter Sites Loose connections between wire loops and counter. This produced low ADT counts on random days. Programmed wrong spacing between loops in lane. This produced bad speed and length data all the time. High axle signal error percentage in high volume site with tubes installed across both lanes of traffic. This produced bad speed records for one lane and low ADT counts all the time for one direction (southbound lane). Wire Loop CounterRubber Tube Counter
End of Presentation Thank You