Fuel Consumption Reduction Experienced by Two PROMOTE-CHAUFFEUR Trucks in Electronic Towbar Operation

6-9 November 2000

Summary Information

This study measured the fuel consumption benefits of an electronic towbar system designed to electronically couple two heavy-duty trucks without using a mechanical towbar. The electronic system made it possible for a trailing truck to autonomously follow a lead truck at spacing distances from 6 to 16 meters. The driver of the trailing truck was relieved from routine work loads such as lane keeping, speed control, and distance adaptation.

Simulations and field trials were conducted to evaluate the fuel consumption benefits derived from slipstream effects. Prior to field trials the author gave theoretical estimates of fuel consumption based on drag forces of simple geometric shapes.


The simulation results indicated a 40 ton trailing vehicle traveling at 80 km/h would reduce fuel consumption by 17 percent if 10 meter spacing was maintained.

The accuracy of the simulation results was limited by complexities in the aerodynamic drag coefficients.


The field trials were conducted using two heavy-duty ACTROS Daimler-Chrysler trucks equipped with an electronic towbar system developed by the European research project PROMOTE CHAUFFEUR. The lead truck was driven manually and the trailing truck was completely operated by an in-vehicle controller that automatically maintained following distances and position.

The electronic towbar system consisted of a vehicle to vehicle controller (VVC), a towbar vehicle controller (TVC), and an image processing system (IPS). A special pattern of infrared lights was attached to the back of the lead truck to enable the IPS on the trailing truck to gauge distance and position.

The experiments were conducted on a 12 kilometer (km) oval test track in Papenburg, Germany. Fuel consumption was measured from a series of test runs using various spacing distances (5 to 16 meters), and two different constant velocities (80 km/h and 60 km/h). The wind conditions were estimated to be similar for each test run. The lead truck had an empty trailer and weighed 14.5 tons, and the trailing truck was loaded and weighed 28 tons. Each test run was conducted with each truck travelling individually, and then again with both trucks traveling as a platoon. The fuel consumption was measured for each test run.

The trailing truck experienced a considerable fuel savings in the whole range of spacing distances for both velocities. The reduction increased with decreased spacing distance and a constant value (plateau) was reached for distances less than 10 meters. Overall, the reduction in fuel consumption ranged from 15 to 21 percent at 80 km/h, and 10 to 17 percent at 60 km/h. There was a 3 percent fuel consumption error factor at 80 km/h, and a 4.4 percent fuel consumption error factor at 60 km/h.

The lead vehicle also experienced a reduction in fuel consumption. At 80 km/h and 10 meter spacing, the lead vehicle decreased fuel consumption by 7 percent.

The author noted the results in this study were limited to an application of electronic towbar operations for two heavy-duty ACTROS trucks under ideal track conditions in Papenburg, Germany. The application of these results to normal traffic conditions would require further experimentation on public highways using different loads.

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Fuel Consumption Reduction Experienced by Two PROMOTE-CHAUFFEUR Trucks in Electronic Towbar Operation

Author: Bonnet C., and Fritz

Published By: Paper presented at the 7th World Congress Conference on ITS. Turin, Italy

Source Date: 6-9 November 2000


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Benefit ID: 2001-00217