Session 12a: Vehicle productivity 2
Minimizing operating costs by specifying trucks based on
operational statistics
Johan Wangdahl, Scania, johan.wangdahl@scania.com
Erik Dahlberg, Scania, erik.dahlberg@scania.com
In the process of specifying a heavy truck optimized for its transportation task, several
choices, balancing between performance and economy, are required. Traditionally, a market
standard vehicle or a copy of the old vehicle specification has been offered to customers. Or
at the best, a set of operational factors are put into an optimization program proposing the
best vehicle specification.
This paper is aiming at presenting and comparing different approaches on specifying heavy
trucks. The actual performance and operating economy is compared for vehicles specified
using three different methods. The first vehicle is based on market standards, the second is
optimized based on operational factors given by the customer while the third is optimized
using detailed operational statistics read out from vehicles in the customer’s actual operation.
Today, a large portion of the European trucks are optimized for operation at 100 % of legal
weight and dimensions, 100 % of the transport time, e.g. 40 tonnes gross train weight (GTW).
In reality, GTW is far below that for a great portion of the transports, i.e. they are volume
limited. Trucks are also driven empty when there is no or small transportation needs on the
return trip. Hence, trucks often use less than full loading capacity. In optimising for the real
need, there is a large saving potential indicating both lighter and more fuel efficient trucks,
e.g. with down-sized engines. By utilising vehicle operational statistics and an optimization
program, trucks specifications better adjusted to the transportation task can be offered to the
costumer.
Operational statistics collected from 157 Scania 4x2 tractors with 420 horsepower Euro 4
engines in European long haulage operation indicate that 20 % of trucks run with over 30
tonnes GTW in less than 20 % of the time. The same statistics also indicate that the cruising
speed is often, but not always, 89 km/h. The actual cruising speed for each operation should
be considered in vehicle specification optimisation.
Specification changes like shifting to smaller engines and lighter chassis may hence decrease
operating costs. However, this must be evaluated together with the possible decrease in
performance, e.g. the possibility to climb hills with inclinations that frequently occur, without
a considerable drop in cruising speed. It is also important to verify that total operating costs
are minimised. One disadvantage with an optimized specification could be that the truck
becomes less competitive in an alternative operation. This indicates that the residual value for
such a truck is lower than for one that is somewhat over-specified, i.e. too heavy and strong
for its actual first life operation. The accumulated savings over the first couple of years must
exceed the drop in residual value.