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Aerodynamic Trailer Skirts

Project Overview: This demonstration project field-tested aerodynamic skirts on trailers to reduce fuel consumption, greenhouse gas (GHG) emissions and criteria air contaminants (CAC).

Organization: Cascades Transport Inc.

Project Timeline: January 2009 to December 2009

Project Results: Performance and financial results are presented showcasing results as observed by Cascades and results on a 'per unit' basis derived from Cascades findings. More information on both the performance and financial results are available in the Detailed Project Results section of this case study.

     Performance
  Fuel Consumption
Reduction (%) 		Fuel Consumption
( L / 100km) 		Annual
Fuel
Savings (L) 		GHG Emission
Reductions

Objective

Actual

Without skirt

With skirt

Per Unit (200,000 km) 5 5.26 40.0 37.9 4,200 11.3 tonnes
Fleet Totals
(11,200,000 km) 		5 5.26 40.0 37.9 188,160 506.2 tonnes
       Financial
  Capital Cost
for Trailer
Skirts 		Annual
Fuel
Savings 		Annual cost
savings 		Project
Payback 		Ongoing
Yearly Profits
Per unit $ 2,505 4,200 L $ 5,670 5 months $ 5,670
Fleet Totals $ 606,294 188,160 L $ 254,016 2.4 years $ 254,016

Project Description

Cascades Transport Inc. is a subsidiary company that provides local, regional and international transportation service for the products manufactured by Cascades Inc. With funding from Transport Canada’s Freight Technology Demonstration Fund, Cascades Transport Inc. began a demonstration project to field-test aerodynamic skirts on trailers to reduce fuel consumption, greenhouse gas (GHG) emissions and criteria air contaminants (CAC).

The objective of the project was to conduct wide-scale testing of aerodynamic skirts. Of the 500 trailers operated by Cascades Transport Inc., 242 were selected for installation of the skirts based on their age and remaining service life as highway trailers.  The skirts were installed mostly on 53- foot, 3-axle trailers but also on 48- and 53-foot, 2-axle trailers. All the trailers were light-aluminum construction and were hauled by the 56 trucks operating from the Kingsey Falls terminal.

All the skirts tested were manufactured by Transtex Composite and measured 15, 18 and 23 feet in length, depending on the trailer type. The skirts were 30 inches in height and had a 15-inch ground clearance, making it possible for trailers to negotiate loading ramps.

Methodology

The fuel consumption for each make and model of truck and its trailer (length, axle configuration and the presence or absence of skirt) for a given trip was tracked. These observations allowed for the capture of data of the various possible configurations and the tracking of fuel consumption and efficiency.

Detailed Project Results

A) Performance Results

The best result, an improvement of 6.69 % in fuel consumption, was achieved with 53-foot, two-axle trailers. An improvement of 4.34 % was observed on 53-foot, three-axle trailers and a 4.99 % improvement was observed on 48-foot, two-axle trailers. The overall fleet improvement recorded by Cascades does not correspond to an average of these improvements but is rather a function of the use made of each of these trailers. Therefore, the overall fleet efficiency improvement recorded was 5.26 % and this led to annual fuel savings of 188,160 L, which translates to 506.2 tonnes of GHG emission reductions.

Other noted advantages were:

  • The skirts did not accumulate snow and ice in winter conditions.
  • There was no appreciable increase in maintenance required by the installation of the skirts.
  • The skirts reduced splashing, thereby improving visibility for other vehicles (as observed by Cascades’ drivers).

B) Financial Results

The 5.26% average improvement in fuel reduction equates to an annual saving of 188,160 L of diesel fuel based on an annual total travel distance of 200,000 km per tractor and a baseline fuel consumption of 40 L/100km. Based on a price of diesel at $1.35 per litre, the annual cost saving was $254,016.

The payback period was calculated to be 2.4 years for Cascades’ investment, based on Cascades’ active fleet for this project and driving patterns. With a an active fleet of 56 tractors and 500 trailers for this project, a large portion of Cascades’ trailers are idle at any given time, and with 242 trailers equipped with skirts, a large portion of this sub-group is also idle at any given time – at least 186. This operational characteristic increases the length of the payback period.

Using Cascades observations and results, a payback period was also calculated for a single piece of equipment used 100% of the time. For this case, the payback is considerably shorter, taking only 5 months to recuperate the investment. Tables 1 and 2 show the figures used to arrive to these conclusions.

         Table 1 - Fuel Consumption Reduction
  Total distance
travelled 		Fuel
consumption 		Fuel consumption
Reduction 		Annual fuel
reduction
Per Unit 200,000 km 40 L / 100km 5.26 % (37.9 L/100km) 4200 L
Fleet Total 11,200,000 km 40 L / 100km 5.26 % (37.9 L/100km) 188,160 L*

* 188,160 L was obtained by calculating the fuel savings resulting from the use of trailers with skirt 80% of the time and trailers without skirt for the remaining 20% of the time.

       Table 2 – Fuel Savings and Payback
  Annual Fuel
Reduction 		Annual Fuel Cost
Savings (based on $1.35 /L) 		Capital cost for 242
pairs of skirts 		Payback
period
Per Unit 4,200 L $ 5,670 $ 2,505 5 months
Fleet Total 188,160 L $ 254,016 $ 606,294 2.4 years

Conclusion

As a result of this demonstration project, Cascades Transport Inc. now orders all new 2- and 3-axle trailers equipped with skirts.

Several other transportation companies have inquired about the performance of the skirts and
Cascade Transport Inc. has provided the following recommendations:

  • Obtain top management support by demonstrating payback potential;
  • Designate a project manager supported by a multidisciplinary team including mechanics, managers and dispatchers;
  • Determine which trailers would most benefit from the skirts and when they should be installed;
  • Establish fuel consumption prior to installation so that improvement can be measured; and
  • Maintain high quality control during installation to minimize corrective maintenance later.
Date modified:
2012-02-16