^SmartWay
     Transport Partnership
     U.S. ENVIRONMENTAL PROTECTION AGENCY
                              A Glance at
           Clean  Freight Strategies
 Improved  Aerodynamics
   Using a streamlined profile tractor with aerodynamic devices will reduce fuel costs by over $800 per year and
   eliminate over five metric tons of greenhouse gas emissions compared to a classic profile tractor.
  What is the challenge?
  Aerodynamic  drag  (wind resistance) accounts for
  most truck  energy losses at highway  speeds.
  Reducing drag improves fuel efficiency. The longer
  the drive and  the higher the speed, the greater the
  potential efficiency benefits. Manufacturers made
  significant progress over the past two decades in
  reducing the  drag  coefficient (a measure of wind
  resistance) of a typical freight truck from about 0.8 to
  about 0.65 - an improvement of nearly 20 percent.
  Additional efforts to improve aerodynamics could
  result in a further 20 percent reduction in the drag
  coefficient. This could have a significant impact on
  fuel  economy. For example, cutting drag by 25
  percent could  raise fuel economy up to 15 percent at
  highway speed.

  What is the solution?
  A number of options exist to improve aerodynamics
  and improve fuel efficiency.

  Tractor Aerodynamics
  Truck  tractor  aerodynamic options  include roof
  fairings (an integrated air deflector mounted on the
  top of the cab), cab extenders (known as gap seals,
  which reduce the gap between  the tractor and the
  trailer), side fairings, and a front bumper air dam (to
  reduce  air   flow  beneath  the  truck).   Truck
  manufacturers offer aerodynamic models that include
  a streamlined front profile, sloped hood, and  a full
  package of add-on devices. These tractor  models
  can improve fuel economy by up to 15 percent, when
  compared to  similar models without aerodynamic
  devices. For a typical combination truck, improving
  aerodynamics by 15 percent would cut annual fuel
  use by up to 2,430 gallons and save up to $3,644 in
  fuel costs.

  Trailer Aerodynamics
  Traileraerodynamicscan be improved minimizing the
  gap between the tractor and the trailer, to reduce air
  turbulence. Specifying  wheelbase  and  fifth-wheel
  settings that position the trailer as close to the rear of
  the tractor as possible can reduce tractor-trailer gap.
  Reducing trailer  gap  from  45  to 25 inches could
  improve fuel economy as much as 2 percent. Another
  innovative trailer option  is to use side skirts. These
  panels hang down from the bottom of a trailer to
  enclose the open space between the rear wheels of

U.S. Environmental Protection Agency • Office of Transpor
     the  tractor  and the rear wheels of the trailer.
     According to the manufacturers, trailer side skirts can
     improve fuel economy by up to 5 percent. Cargo
     "profile" is also important. On flatbed trailers, reduce
     drag  by arranging cargo as low and smooth as
     possible. Secure  loose  tarpaulins and close the
     curtains on empty curtain-sided trailers to improve
     fuel economy by up to 2.5 percent and 4.5 percent,
     respectively.

     Single Unit Truck Aerodynamics
     Many new  single-unit truck models incorporate a
     sloped hood and a more streamlined front profile as
     a standard feature in order to reduce drag. Rounded
     air deflector bubbles can be added to single-unit
     trucks with van-style  bodies to  reduce  drag;
     manufacturers claim fuel economy benefits of 5 to 10
     percent. This would yield annual fuel savings of 82 to
     165 gallons, saving $124 to $247 in fuel costs. Single
     unit trucks with higher annual mileage could realize
     even larger benefits.


     The results are in ...
     Using a streamlined profile tractor with aerodynamic
     devices  (roof  fairing, cab extenders,  and   side
     fairings) can reduce  fuel costs by over  $800 and
     eliminate over 5 metric tons of carbon dioxide per
     year compared to a classic profile tractor. When
     installed on  van trailers,  aerodynamic  devices can
     produce comparable fuel and emission reductions.
     Some aerodynamic options are standard on many
     trucks,  like  a  streamlined hood. Others may be
     purchased and installed for an additional cost. The
     initial expense of these  options  is often  quickly
     recouped through fuel savings.


     Next  steps
     Trucking firms should specify aerodynamic options
     when purchasing a new truck and consider adding
     aerodynamic devices to existing trucks. In  most
     cases, the cost to purchase the devices is  soon
     recovered in fuel savings. For  more information on
     aerodynamic devices, contact yourlocal truckdealer,
     truck equipment vendor, or trucking association.
February 2004. EPA420-F-04-012. • For more Information,, visit: www.epa.gov/smartway

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