Using GPS to Track Pole Truck Turning Movements

Presented by:

John Wolf, PE

Senior Designer

ODOT, Region 1 Preliminary Design

&

Ron Singh, PLS

Chief of Surveys/Geometronics Manager

ODOT, Technical Services

The Problem

• Intersection at Bennett Road & US 30– High volume, multilane highway– 3 Crashes in 2008 involving passenger cars and log

trucks– 2 injuries and 1 fatality resulted

• Permitting issue regarding overhang on long loads– Maximum Overhang was dependant on wheelbase

and trailer type– Overhang was measured from rear axle

• Pole trucks need access to pole yard

Bennett Road

Conflict Point

Bennett Road

Accidents at Bennett Road

Accidents at Bennett Road

The Challenges

• Timing was critical– Motor Carrier issued a pilot car requirement on log trucks with

large overhang, effective 9/12/08, for over 260 permit holders

• Variable vehicle configurations (What should be analyzed?)

• Pivoting trailer bunks influence log sweep path• Turning movement software limitations?• The need to applying the turning movements to multiple

situations– Multiple intersection configurations– Freeway ramp terminals– Multilane Roads

Unique Elements of A Pole Truck

Adjustable Stinger Hitch and Compensator

Front Bunk/Pivot Point

Rear Bunk/Pivot Point

Large OverhangLong Wheelbase

Extendable Stinger

12’6” Total Length

5’6” Available Adjustment

Compensator

Vehicle #2

13’

12’

AutoTURN v5.1

• AutoTURN is a CAD-based program that simulates low speed turning maneuvers for highway vehicles

– Vehicle inputs• Default vehicle configurations• User defined vehicle configurations• Inputs include number of axles, axle spacing, tractor/trailer

length, and distance to pintle hitch– Limitations

• AutoTURN v5.1 does not account for adjustable length “stinger” pintle hitch

• Turning accuracy for this type of tractor/trailer uncertain

AutoTURN Inputs

Default truck templates

Modified pole truck templates

AutoTURN Outputs

Course of Action

• Collected data from ODOT Motor Carrier on common pole truck configurations

• Research other turning simulator software• ODOT Maintenance staff coordinated field

testing of two pole trucks using GPS tracking data

Note: ODOT Motor Carrier Division also collected data on accident history of pole trucks on Oregon highways and neighboring states log truck permitting requirements

OREGON STATE FAIRGROUNDS – TEST SITE

The Survey Approach

Truck Turning Sequence

Test Vehicle #2

Ribbons Spaced at 5’ Intervals From Rear Bunk

5’ 5’5’5’5’

12’ Between Cones

12’ Between Cones

Cones Offset 2’ from Path for Driver’s Side Front Tire

GPS Devices

After Data Collection

• Create vehicle configurations to replicate field test

• Run AutoTURN analysis

• Compare results

• Run sensitivity analysis of sweep path based on overhang length

• Report Results to Motor Carrier and the Trucking Industry

No Scale

RAW GPS DATA COLLECTED

Comparison of Field Tests to AutoTURN – Vehicle #1

Comparison of Field Tests to AutoTURN – Vehicle #2

General Findings of Field Test and Analysis

• Sweep path is dependent on vehicle configuration and length of overhang from the rear bunk

• Sweep path is the same for both left and right turns• AutoTURN v 5.1 reasonably predicts pole truck turning

movements for various conditions– Path generated using AutoTURN v 5.1 predicted log sweep

within 2’ for Vehicle #1 and 1’ for Vehicle #2 compared to GPS– AutoTURN's maximum error in the trailer off tracking was

between ½’ and 2’ (2’ occurred as the vehicle exits the curve) – Multiple curves compound the error in the AutoTURN software

Outcomes

• ODOT Motor Carrier changed permitting requirements for overhang, effective 11/24/2008– Length of overhang was limited to 1/3 Wheelbase with

a 25’ maximum for multilane roads– Changed the point which overhang is measured from– Lifted the temporary pilot car restriction for vehicles

meeting these requirements– Requirements are posted at:

http://egov.oregon.gov/ODOT/MCT/• Currently investigating an intersection

improvement project at US 30 and Bennett Road to better accommodate pole trucks

Questions?