THE SCIENCE BEHIND THE SEAT–Kiel Group
SEATING works to improve fuel efficiency
By Jürgen Mill
The virtues of fuel efficiency
Although the use of public transportation is saving over 4 billion gallons of fuel annually that would otherwise end up in the gas tanks of private vehicles, the combined fuel consumption of motorcoaches in North America alone is enough to fill up almost all of the 110 floors of the Willis Tower to its 390 million-gallon capacity. The volatile cost of fuels, combined with rising operational costs, is enough to make operators explore more fuel-efficient options for their fleets. Additionally, state, federal and local mandates for reduced carbon emissions and better air quality push for an ever increasing fuel efficiency in today’s vehicles.
Reducing vehicle weight is one of the most effective ways to save on fuel costs, and the EPA estimates that for every 100 pounds taken off a vehicle, its fuel economy increases by 1-2 percent. Less weight can also mean less wear and tear on the vehicle’s axles and breaks, for example, and therefore a longer service life.
Science diet for seats
An empty 45-foot coach weighs about 50,000 pounds (passengers plus baggage may add another 30 percent) but it is extremely challenging or almost impossible for bus builders to alter their tried-and-proven technology to shed off pounds. More likely, it is the seat manufacturer who can bring value into the equation by offering a lightweight seat that fulfills every safety requirement while satisfying customer expectations for exceptional comfort and great design. After all, every pound shaved off one seat quickly adds up if multiplied 50 or 55 times.
Over the last 15 years, Kiel seats have lost about 30 percent of their weight and the company continues to invest much of its R&D into the advancement of lighter materials. Kiel’s ESOS for example (a versatile model for city buses) weighs only 26 pounds per double seat, and despite its luxurious looks, the popular coach seat Avance 2050 weighs only 60 pounds (per double seat with aluminum rails). Compared to an average 75-pound double seat, the 15-pound difference reduces the overall bus weight by over 400 pounds per 55-seat set.
Saving weight and saving lives
A great way to bridge the dichotomy of comfort vs. safety (and to satisfy the strict North American requirements for material strength) is to implement high-grade materials and engineering concepts that absorb energy (e.g., from an impact) more intelligently by entering a carefully calculated state of controlled plasticity.
Metals like high-alloy steel and a special engineered aluminum are crucial for a successful lightweight design, as they can be processed into thinner sheets (which saves weight) while maintaining their excellent plasticity characteristics (which saves lives). The goal of “intelligent absorption design” is always to integrate metals that do not break like a brittle piece of Wasa bread but rather like a piece of chewed bubble gum that has the capability to deform without compromising structure.
What is good for fuel efficiency, it turns out, is equally good for the safety of passengers.
The future of fuel-efficient seat design
The research of new materials and their usefulness as lightweight design material is an exciting field for engineers and one with considerable depth. The automobile industry has started working with metal foams that weigh only a fraction of traditional metal sheets. In addition to being true lightweight wonders, they also exhibit phenomenal material strengths and safety features as tiny air bubbles sandwiched between the outer sheets act as “mini-airbags.” While their application in the bus and rail industry is still a bit further into the future, it is never too soon to start thinking about new ways to implement these metals into an even lighter seat design.
Jürgen Mill is senior VP of engineering and R&D at the global headquarters of the Kiel Group. Kiel is a trendsetting seat provider to transit systems around the world including seating solutions fort buses and trains on the local, regional and intercity level. Visit www.kielna.com