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1 INTRODUCTION

In 2013, the value of waste and recycling equipment

by European producers is estimated at just over $ 1

billion [3]. Alternative fuel garbage trucks are

increasingly used across Europe as fleets seek to

replace older diesel trucks with hybrid vehicles and

cleaner burning CNG and biomethane vehicles. The

share of CNG / biomethane trucks in new orders has

been increasing in the last few years and is expected to

continue to increase. Common reasons to choose

alternative fuel vehicles are fuel efficiency, lower CO2

and particulate emissions, and quieter operation.

However, one aspect of the discussion of the

requirements to be considered for a garbage truck is

the suitability of the driveline to the operating

conditions. This is especially important in large cities,

where driving conditions are very difficult and

strongly affect the driving parameters of trucks. The

analysis presented in the article is based on data from

heavy garbage trucks operated in Warsaw. It gives the

argument that it is necessary to work on an efficient

way to power the garbage truck (special drive system

of the garbage truck) or change the entire system of

collecting waste from cities and specialized areas,

such as ports. The importance of organizing waste

transport, but also means of transport, is described in

[1]. The author estimated and presented the values of

the global warming potential (GWF), which express

the potential contribution to global warming as a

result of collection, transport and shipment of 1 ton of

wet waste. GWFs ranged from 9.4 to 368 kg CO2

equivalent (kg CO2 equivalent) per tonne of waste,

depending on collection method, capacity and choice

Garbage Truck Operation in an Urban Area

P. Olszowiec

Kazimierz Pułaski University of Technology and Humanities in Radom, Radom, Poland

ABSTRACT: Optimizing energy consumption, as well as the need to reduce greenhouse gas emissions, should

be taken into account when building city trucks, especially heavy trucks for waste collection. The driveline is

particularly important. Currently, there is a choice of possible driveline systems for a truck, but the

conventional internal combustion engine is still the dominant solution. The article describes the driving

characteristics of a city truck, in particular the operation of an internal combustion engine in such a truck. On

the basis of data collected from several garbage trucks equipped with a compression ignition engine and

compression ignition engines powered by CNG, an analysis of the load structure and engine rotational speed

was presented. These vehicles operate in urban conditions and perform specific tasks. The data shows how

ineffective the operation of an internal combustion engine is when operating a truck in a large city and in

specific areas, e.g. a port. The reason is the very low load at low engine speed which dominates the performance

characteristics of the truck. The analysis provides arguments that there is a need to change the way they are

powered trucks, there is a need to replace the powertrain based on an internal combustion engine with a more

efficient one.

http://www.transnav.eu

the International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 15

Number 4

December 2021

DOI: 10.12716/1001.15.04.25

912

of transport equipment, and distance to be traveled. It

is also an argument to analyze and work on efficient

and environmentally friendly transport. Now it is still

based on the IC engine. Despite some proposition of

propulsion systems, such as hybrid or electric drive,

the internal combustion engine is still the main source

of power for such a truck, so the analysis of its

functionality and efficiency, especially in the urban

and specialist area, is crucial.

2 SPECIFIC FUEL CONSUMPTION AND VEHICLE

TASKS

The specific fuel consumption of IC engine strongly

depends on load and engine speed. Minimum specific

fuel consumption will typically be seen at or near full-

load and at relatively low engine speeds. As engine

speed increases, the engine becomes less efficient due

to the rapid rate of friction increase. At low speeds,

the specific fuel consumption will again increase

because of increased heat transfer losses. This

phenomenon is more pronounced in diesel engines, in

which the air-to-fuel ratio drops with the increased

torque. This results in increased flame temperatures

during combustion and minimum specific fuel

consumption typically occurring between rated and

peak torque speeds. As load is reduced at any speed,

the specific fuel consumption again increases. This is

due to a combination of increased pumping work and

the fact that friction losses stay relatively constant

while the brake output is dropping (Fig. 1a). The

specific fuel consumption increases more rapidly as

load is reduced with the spark-ignition engine than

with the diesel (Fig. 1b). This is due to the increased

pumping work associated with the throttled intake on

the spark-ignition engine [1].

Figure 1. Typical operating map, showing lines of specific

fuel consumption for: a) diesel engine; b) spark ignition

engine

The relationship between specific fuel

consumption and engine overall efficiency is

described by the formula:





qe - specific fuel consumption [g/kWh]

Wu – fuel calorific value [kJ/kg] or [kJ/m

]

The maximum overall engine efficiency of

contemporary IC engine reaches 43-45% (especially CI

engine) but as it was described it is the only one point

of minimum specific fuel consumption from engine

operating map. Variety of loads and engine speeds

makes the engine far less efficient. The art of vehicle

design also includes an appropriate fitting of the size

and power of IC engine to the vehicle tasks.

Sometimes it is very difficult to chose the right engine

characteristic to ensure vehicle functionality and

minimize the fuel consumption, especially specific

fuel consumption. The good example of this is typical

heavy garbage truck operates in urban conditions. A

vehicle for urban transport should ensure low

operating costs but primarily must comply with

restrictions on emissions and noise. The process of

garbage collection creates specific requirements. At

the start the truck is empty and its load increases

during the collection process. The dump of the

garbage is often connected with the drive on a slope,

miry road.

3 HEAVY GARBAGE TRUCK IN THE URBAN

ENVIRONMENT

The refuse collection industry faces various issues that

determine the choice of type of heavy garbage truck

and its powertrain. Heavy-duty engine strict

emissions standards impose the use of EURO 6

engines. Despite of mentioned in the introduction

alternatives of engine fuelling, in practice there is very

limited choice. Typical IC engine for three axles urban

garbage truck is 280 - 340 HP (maximum torque 1400

– 1800 Nm) engine. One could choose EURO 6

compression ignition engine fuelled with diesel oil or

alternatively it’s possible to use spark ignition engine

fuelled with CNG or far less frequently biomethane to

power the truck. The choice of CNG seems to be

attractive from the point of view of a cost of the fuel

but limited millage between refueling and the volume

of the tanks is a drawback. Engine and vehicle

manufacturers are pursuing different compliance

strategies that will affect fuel efficiency and emission

differently but still there is impossible to fit the engine

characteristic to the conditions which impose urban

environment and the character of the task. The truck

has a lot of stops and starts, and its ride consist of

acceleration, deceleration and limited stretches of the

road where the truck moves with low, constant speed.

Additionally during the stay and loading of the

garbage the engine provides power to the body

equipment by the use of power take off. This issue

was discussed, among others, in the extensive

material Characterization of Municipal Solid Waste

Collection Operations by Megan K. Jaunich. The

influence of numbers of starts and stops of the heavy

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truck equipped with IC engine on a fuel consumption

was examined and described illustrates Fig. 2.

Figure 2. The influence of number of stops per 1 km on

heavy truck fuel consumption

Even that the levels of fuel consumption are now

lower than in year 2000 when the tests presented in

Fig 2 were carried out its results show the

phenomenon which strongly influences contemporary

urban garbage trucks equipped with IC engines. A lot

of stops of the trucks are caused not only by the points

of collecting wastes but also by traffic, especially by

traffic lights.

4 THE WORK DATA OF SELECTED URBAN

TRUCKS

The data taken from the heavy garbage trucks

operating in Warsaw includes the structure of trucks

speed as well as the structure engine load and speed

which is the most interesting from the point of view of

efficient way of its run.

The data are divided into two groups of trucks

equipped with:

1. CI engine fuelled with standard diesel oil,

2. SI engine fuelled with CNG.

4.1 Garbage truck speed in urban area

The structure of trucks speed is presented in the Fig.

3. but Fig. 4 presents the average garbage truck speed

calculated for 10 trucks which was calculated

according to the formula 1:

(vx m )



(1)

where:

n – number of the truck,

vxav – the average share of truck speed in the chosen

range (eg. 0-10 km/h) in the whole range of average

truck speed [%],

vxi – the share of single truck speed in the chosen

range (eg. 0-10 km/h) in the whole range of single

truck speed [%],

mi – examined single truck millage [km],

Figure 3. Garbage truck speed structure

a) the truck equipped with CI engine

b) the truck equipped with SI engine

4.2 The garbage truck IC engine speed and load in urban

environment

Figure 4. The load and engine speed structure for single

examined truck (for average truck)

a) the truck equipped with CI engine

b) the truck equipped with SI engine

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5 CONCLUSIONS

Heavy garbage trucks that work in urban conditions

perform specific tasks. The data shows how inefficient

the operation of an internal combustion engine is

when a truck is operated in a large city. The reason is

the very low load at low engine speed which

dominates the performance characteristics of the

truck. Figure X1 shows areas on operational maps that

are very ineffective. The area corresponds to the

operating points of the analyzed trucks. Heavy

garbage trucks that work in urban conditions and in

closed areas such as ports perform specific tasks. The

data shows how inefficient the operation of an

internal combustion engine is when a truck is

operated in a large city. The reason is the very low

load at low engine speed which dominates the

performance characteristics of the truck. Figure X1

shows areas on operational maps that are very

ineffective. The area corresponds to the operating

points of the analyzed trucks.

The analysis provides arguments that there is a

need to change the method of powering such a truck,

especially since there is a need to replace the

powertrain based on an internal combustion engine

with a more efficient one. A good solution is to use

two motors. The hybrid driveline appears to be

effective because of the two engines (internal

combustion engine and electric motor) that can be

used separately and together when a truck needs

maximum power.

Figure 5. X1 Schematic engine map with inefficient engine

run area

For a garbage company, the most important thing

is the cost of buying a truck and the cost of

maintaining it. The data presented in the article are an

argument for a thorough analysis of the costs of a

truck with only an internal combustion engine and a

hybrid truck.

REFERENCES

1. Eisted, R., Larsen, A.W., Christensen, T.H.: Collection,

transfer and transport of waste: accounting of

greenhouse gases and global warming contribution.

Waste Manag Res. 27, 8, 738–745 (2009).

https://doi.org/10.1177/0734242X09347796.

2. Hoag, K., Dondlinger, B.: Vehicular Engine Design.

Springer-Verlag, Wien (2016).

https://doi.org/10.1007/978-3-7091-1859-7.

3. Refuse Truck Body Manufacturing in Europe,:

SpecialtyTransportation.net. (2014).