Lehigh and Northampton Transportation Authority officials considered acquiring diesel-electric hybrid buses in earnest in 2007 and 2008, when crude-oil prices topped $100 per barrel, pushing the cost of diesel fuel for the agency's buses from $2.15 to $3.15 per gallon in a year's time.
Fuel prices later eased, but LANTA's interest in hybrid buses, which also emit fewer air pollutants, remained on the inside track. When federal stimulus money became available, LANTA leaped at the chance and secured $3 million to buy buses that use electric motors to supplement their fossil-fuel engines, much like the Toyota Prius and other hybrid cars.
The hybrid buses, which took to the road in July, look and behave much like regular diesel-only transit buses. "Beautiful," concluded 15-year veteran driver John Cox when asked how the hybrids drive. "It's like driving a Cadillac … I love it," Cox said, wheeling the 35-passenger hybrid made by Gillig Corp. in Hayward, Calif., out of the Allentown Transit Center terminal in Allentown recently.
Though it took some time to get used to the slightly different braking characteristics of the hybrids, Cox said it's actually a little easier driving them compared with pure diesel buses. In both types of vehicle, drivers experience a braking effect when they ease off the gas, but the effect is amplified with the hybrids, Cox said, allowing drivers to apply less brake-pedal pressure.
Gillig Vice President Joe Policarpio said the hybrids boost fuel mileage by 25 percent to 30 percent on average, depending on the type of driving that prevails. As with the Prius, the gain is greater in stop-and-go city driving than in highway applications, he said.
LANTA's figures from July and August show that 2006 model diesel-only 35-foot buses made by Gillig averaged 3.85 miles per gallon, while 35-foot 2010 hybrids managed 5.56 miles per gallon, a 44 percent boost. The comparable 40-foot hybrids did even better, bumping the average from 3.36 to 5.47 miles per gallon, a soaring 62.7 percent increase. A portion of those gains might be attributable to the older age of the diesel-only buses, but the percentages are significant, easily exceeding Policarpio's estimate.
Policarpio said the vehicles also offer reduced air-pollution and greenhouse-gas emissions because they use smaller, cleaner-burning diesel engines and the electric motors bear the brunt of the most strenuous load — getting the heavy vehicles moving from a dead stop. The hybrids take advantage of a kind of "sweet spot," allowing the fossil-fuel engine to do more of the easier work once the vehicle is moving at 30 mph or more. "It's really great technology for a transit bus," he said.
Unlike the Prius, which operates initially on the electric motor alone, the Gillig's diesel engine always runs, and the computer system continually shifts the load between the two power sources in the most efficient manner, Policarpio said.
From the passenger's point of view, the hybrids are nearly identical in outward appearance and on-board experience. Policarpio said they're a touch quieter, and Cox's hybrid seemed so. The ride seemed a bit smoother, with less engine vibration. "It's a good bus, real good," said passenger Charles Rodgers of Orefield, who like other riders endorsed the idea of saving fuel.
What puts hybrids out of reach for some transit agencies is cost. Though prices can vary depending on specified equipment, LANTA paid $526,000 for each of its three 35-foot hybrids and $531,000 apiece for two 40-footers, blowing the average $350,000 sticker off the window of comparable diesel-only transit buses.
LANTA's had no major problems with its five hybrids thus far, and based on this limited experience, Executive Director Armando Greco said the agency hopes to acquire more of them, though it will depend on finances.
"Our vision is to replace the whole [80-bus] fleet with hybrid vehicles and the next generations [of bus technology] as we move forward," Greco said, "but that will depend on the availability of the money" required.
It's unlikely that stimulus money such as that used for the first five hybrids will be available in the years ahead, but if the hybrids hold up, their purchase could prove financially sound, regardless of the funding source. Using even anticipated longer-term fuel savings averaging 30 percent to 40 percent, LANTA figures it will take eight to nine years to recoup the extra cost of the hybrids, depending on fuel prices.
The buses are expected to last 12 years or more, Greco said, adding, "On a cost basis, I believe it will work out."