Flexible, cost efficient bus trailers adapt to passenger demand

The cost, environmental and other benefits of the bus trailer concept are obvious. Used in several areas of Germany, as well as Austria, Switzerland, and Luxembourg, vehicle sizes can be adapted to passenger demand

The 1062 Ruebenacker group, a public transport provider in the Black Forest region of Germany, is one of more than 20 bus operators in the country that have deployed bus trailers, also referred to as bus trains. The company owns 81 buses and transports nearly six million passengers a year in the Black Forest region, a very hilly, almost mountainous, landscape in the southwest of the country.

Like most bus operators the world over, Ruebenacker faced the problem of massively differing passenger demand not just by time of day, but also by season. Take pupil transport, for instance: in peak hours, large-capacity articulated buses, also referred to as bendy buses, or even additional relief buses are needed while, during the rest of the day, low passenger demand could be served by much smaller and more economical buses.

To solve this problem, in 2006, the Ruebenacker group introduced bus trailers to achieve flexible capacity that could be adaptable to be substantially more cost-effective and efficient. The concept is simple: depending on passenger volume a trailer is attached to the bus. In rush hours, for instance for pupil transport, the capacity of a bus is nearly doubled. During the non-busy periods, including weekends or holidays, only the towing bus is required to meet demand. As a result, no additional weight is carried, fuel costs are lower, and no relief buses or extra drivers are necessary.

Two types

Ruebenacker now operates a fleet of two types of bus trailer – the Midi Train and the Maxi Train, manufactured by German company Göppel Bus. The midi train uses a 9.1m MAN Nutzfahrzeuge low-floor bus, with an 8.3m trailer, for a total length of 19m (62.3ft). Bus capacity of 85 persons is increased by 77 for a total passenger capacity of 162, including standing capacity, when the trailer is attached.

Project:

Use of bus trailers by Ruebenacker group, Germany

Cost:

Approx 65% of comparable seating capacity bus

Benefits:

• Savings of US$375,000 a year

• Higher service life

• Reduced maintenance

• Longer service life

• Fuel cost reductions

• Reduced CO₂

• No additional weight carried

• Fewer relief buses and drivers required Meanwhile, the maxi train uses a 12m 267 MAN low-floor bus with an 11m 1061 Göppel trailer to produce a bus of 23m (75.5ft) total length with a passenger capacity of 200, including standing capacity. The trailers are made of stainless steel and designed for speeds of up to 85km/h (50mph). When a trailer is attached to the towing bus, flexible barrier tapes are pulled into position to prevent people from passing between the bus and the trailer, while CCTV cameras enable the driver to monitor the gap and the interior of the trailer.

What the company has also found is that user and resident acceptance and perception of the bus trailer combination in the narrow streets of towns is higher than for articulated buses. Due to two steered axles, the curve radius of the trailers does not differ from single buses. Interestingly, passengers highlight the silent comfort of the trailers without engine noise.

Cost benefits

In 2010, Ruebenacker calculated the cost benefits of using the modular concept for the fleet of seven bus trailers it deployed. In general, the system provides high flexibility, has minimised both maintenance and operational costs, and provided a positive environmental impact.

Because the company can now do without some of the 18m articulated buses it was previously using as relief buses, and also the cost savings in maintenance, plus personnel costs for three drivers, Ruebenacker is saving €275,000 a year (approx US$375,000).

Moreover, in terms of reductions of fuel consumption, the company calculated these based on mixed operation in solo and with trailer configuration and compared the result to the use of articulated buses. For the midi train the company achieved an improvement of 14.79 litres of diesel per 100km, while the figure for the maxi train was 12.03 litres of diesel/100km. Associated CO₂ reductions amount to 39kg CO₂ per 100 km for the midi train and 32 kg CO₂ per 100km for the maxi train respectively.