At motorway speeds, a large share of the energy consumed by a tractor-trailer combination goes into overcoming air resistance. Aerodynamic equipment developed for box (curtainsider/van) trailers has been known for years; the real question is how much of that gain can be retained on cylindrical-bodied tankers.
What Do the Scientific Findings Say?
A Cambridge-based research team measured the effect of semi-trailer modifications on heavy goods vehicle fuel consumption using real driving data, reporting that combinations of side skirts, rear treatments and gap closure can reach the seven percent band in total. Another North American study examined how tankers and similar non-box trailers are actually used in the field, demonstrating the need for a dedicated catalogue of aerodynamic devices for this segment.
Where the Gains Come From on a Tanker
- Side skirts that tidy up the underbody: the single largest gain item
- Integrating the filling pipe, valve cabinet and pump equipment into the body with fairings
- Minimising the gap between the tractor and the tanker
- Streamlining the rear equipment and marking area for cleaner airflow
Although the cylindrical cross-section starts out as a more favourable form than a box body, the complex equipment underneath and behind the tanker generates turbulence. When these zones are enclosed with sound engineering, a saving of five to seven percent is a realistic target; on a vehicle covering a hundred thousand kilometres a year, that means thousands of litres of fuel.
References
- Madhusudhanan, A. K., Na, X., Boies, A. & Cebon, D. (2021). Effects of semi-trailer modifications on HGV fuel consumption. Transportation Research Part D: Transport and Environment, 92, 102717. DOI: 10.1016/j.trd.2021.102717
- Durbin, T. D., Johnson, K. C., Jung, H. & Miller, J. W. (2021). Characterizing non-box trailer activity and aerodynamic devices for greenhouse gas emissions reductions. Transportation Research Part D: Transport and Environment, 98, 102763. DOI: 10.1016/j.trd.2021.102763