üstra Hannover reorders Allison-equipped hybrid articulated buses

üstra Hannoversche Verkehrsbetriebe AG (üstra) has taken delivery of nine additional Solaris Urbino 18-metre articulated buses equipped with the Allison H 50 EP™ hybrid system. The fleet first tested the Urbino hybrid bus in 2008 and delivery of ten hybrid buses followed in September 2011. Driven by environmental policy in the region of Hannover and Üstra, the decision was taken to continue the focus on hybrid technology and a recent tender resulted in Solaris providing nine additional articulated buses with the Allison hybrid system.

Hubert Nawa, responsible for vehicle engineering and bus workshops for city buses at üstra, explains why it was an easy decision: “The buses, especially the Allison H 50 EP™ hybrid systems, are reliable. In addition, they are fuel efficient, accelerate quickly after a stop and slow down smoothly via the hybrid unit. Of particular note is the quiet operation; we get very positive feedback from passengers and residents.”

The new three-axle, 18-metre articulated buses will replace older vehicles. Satisfying demand as local passenger numbers increase, articulated buses are very popular in Hannover. The buses were delivered in early October, awaiting inaugural runs planned for October 27, 2013 as part of a hybrid bus festival in Hannover.

The buses will primarily be used on lines 127, 125 and 123, where there are short distances between stops, low average speeds and a high concentration of passengers. During stop and go runs, the benefits of these hybrid buses – reduced fuel consumption, emissions and noise pollution as well as recovered braking energy – are most significant. The 11 existing hybrid buses have already been operating on routes with similar conditions. Since September 2011, these buses have accumulated about 1.3 million kilometres (808,000 miles) in regular service, transporting nearly 10.5 million passengers.

Unique Allison hybrid technology

The Allison H 50 EP™ system features a unique two-mode parallel hybrid architecture which blends torque delivered by two electric 75 kW generators with torque generated by a 181 kW (246 hp) Cummins ISB6.7 250H diesel engine. The electric motors contribute substantially to bus launch, relying less on the diesel engine to produce power and torque. High-capacity batteries save the energy released during braking to reuse during accelerations, making the most efficient use of available energy. This offers an important advantage for üstra’s fleet of buses which covered more than 12 million kilometers (7.5 million miles) in 2012.