# 5.5 Fuel Consumption

NTMCalc allows for real operational fuel consumption data and general default data. The default fuel consumption figures are suggested to be applied in calculations for normal European traffic for respective vehicle type and road type, when more situation specific data is not available. The data is extracted from HBEFA and processed by NTM  and represents average values for a large number of road types within each road category. If actual fuel consumption data is available these can be used in NTMCalc.

Fuel consumption values

The fuel consumption data given above is connected to the type of road used by the truck. A typical truck transport between two adresses will of course use a number of different road types along the route. The distribution of the total distance between the three categories Motorway, Rural, Urban can be obtained by analysing a GIS based route planning system. If no data is availabe, national statistics could be used as an approximation, see exampel for Sweden in table below The true distribution is dependent uppon transport length and types of roads available along the route.

Geographical impact

The fuel consumption data given above is connected to the type of road used by the truck. A typical truck transport between two adresses will of course use a number of different road types along the route. The distribution of the total distance between the three categories Motorway, Rural, Urban can be obtained by analysing a GIS based route planning system. If no data is availabe, national statistics could be used as an approximation, see exampel for Sweden in table below The true distribution is dependent uppon transport length and types of roads available along the route.

21%51.7%22.3%

Distribution of HGV traffic activity on different road categories, data for Sweden 2004.Source: ARTEMIS (2008)

Another geofraphical aspect with an impact on fuel consumption is local topography which is included through the road gradient. Data is taken from HBFA and processed in NTMCalc.

Fuel consumption variations due to capacity utilisation

The fuel consumption increases with heavier load. The increase is due to increased rolling resistance and dynamic weight. The increase can be approximated to be linear why the following formula for FC at different loads can be used below equation below.

Fuel consumption as a function of load capacity utilisation

NOTE: The load capacity utilisation (LCU) can be calculated with different units and definitions of cargo, e.g. dimensional weight or volume compensated weight. For the fuel consumption calculation above, the real physical weight of the cargo must be used since the larger dynamic mass and higher rolling resistance connected with the weight of the cargo is the cause of the increase in fuel consumption. The use of volume compensated weight will lead to an overestimation of the fuel consumption.

Fuel consumption variations due to speed variations

It is of interest to investigate the fuel savings from speed changes around the maximum speed 80 or 90 km/h. However, relevant information on this issue could not be obtained from the HBEFA model. NTM will continue to search for reliable data on this issue. The following ‘rule of thumb’ is presented by a Swedish haulier and is valid for the larger truck+trailer combination (max 60 tonne).

Increase from 70 to 80 km/h adds 4 litre extra fuel per 100 km

Increase from 80 to 90 km/h adds 6 litre extra fuel per 100 km

Fuel consumption variations at idle

The fuel consumption for the different vehicle classes at idle is not available as an output from the ARTEMIS model. A number of sources from the internet has been reviewed and it is clear that the consumption is strongly dependent on factors such as engine size, engine idle speed and the power consumption of the vehicle equipment such as climate systems for the cargo hold and the driver cabin, hydraulic and electrical systems for cargo handling e.g. pumps, cranes, lifts etc. The values below should only be viewed as illustrations to the magnitude of the fuel consumption that can be found for idling truck engines.

Fuel consumption from idling truck engines, illustrative examples