Article
citation information:
Blatnický, M., Dižo, J., Lovska, A. Proposal of
a methodology of criterial assessment of technical indicators for the purpose
of selecting an optimal semi-trailer tractor for the needs of a transport
company. Scientific Journal of Silesian
University of Technology. Series Transport. 2025, 127, 5-21. ISSN: 0209-3324. DOI:
https://doi.org/10.20858/sjsutst.2025.127.1
Miroslav BLATNICKÝ[1],
Ján DIŽO[2],
Alyona LOVSKA[3]
PROPOSAL OF A
METHODOLOGY OF CRITERIAL ASSESSMENT OF TECHNICAL INDICATORS FOR THE PURPOSE OF
SELECTING AN OPTIMAL SEMI-TRAILER TRACTOR FOR THE NEEDS
OF A TRANSPORT
COMPANY
Summary. The goal of this work
is to describe the current state of road freight transport from the point of
view of the entrepreneur and the owner of semi-trailer tractors within the
Slovak Republic. The article contains a brief description of freight transport
works and points out the individual aspects of doing business in this sphere in
Slovakia. In the next one, an original criterion evaluation program is created
in the MS Excel application for semi-trailer tractors. In this program, an
owner, a future owner, or a driver of a tractor can compare any number of
tractors. Subsequently, based on the point evaluation, the program determines,
which tractor in the comparison has more points and, therefore, it is more
suitable for business activity. A sample comparison will be made on two
tractors (Swedish and German brands) operated by a commercial transport
company. The parameters of the tractors given, checked and calculated by the
manufacturer are implemented in the criterion evaluation program. In the
criterion evaluation, a tractor of one brand scored more points and therefore
won. All knowledge, results, and conclusions found in the work are discussed
with the management of a commercial transport company and its drivers. Based on
the findings and results achieved, it can be concluded that the criterion
evaluation program is extremely suitable for the application of any tractor,
any brand, and thus the condition of the repeatability of the experiments is
guaranteed. Based on these aspects, all the objectives of the work were
fulfilled, and thus the result of the research is suitable as a decision-making
aid for the purchase of a tractor for the future owner.
Keywords: tractor trailer, criterion evaluation, transport company, calculation
1. INTRODUCTION
Transport is a sector of the national economy
that facilitates the movement of goods and individuals, thereby enhancing the
quality of life and promoting the growth of the enterprise. Transport can be
characterized as a deliberate movement activity carried out by means of
transport, which consists in moving people or things in time and in the space.
After the Second World War, a new field of science, namely logistics, began to
deal with this area. The content of logistics is complex planning, management,
and control of activities that make up logistics chains. Transport is the main
component of these logistic chains. The main task of transport is to ensure the
movement of material within the transfer processes using transport means and
transport routes. In transport, the relocation process is made up of mutually
technological joints, work operations, and processes, with the help of which
the relocation of people or things is carried out. The relocation process can
subsequently be referred to as the operation of transport [1-3].
Transport differs from other branches of the
national economy. In principle, inland, road, and rail transport are possible
to transport large amounts of goods. Therefore, means of road and, rail
transport are still developed, tested and evaluated. While the rail transport
needs new designs of many types of wagons [4,5], truck and semitrailer tractor
designs are under investigation and modernized [6,7]. Ride comfort for drivers
(often also for a passenger – a second driver) one of the most important factors
when a semi-trailer tractor is selected. Other factors are the buying costs,
operational costs, needs for maintenance, and others. Although rail transport
offers some advantages, such as low running resistance, drag, rolling
resistance [8,9], road transport provides goods delivering just-in-time, door
to door and others. Road transport tries to adapt for operation some similar
technologies, such as electric powertrains [10-12] and others; diesel
combustion engines are still widely used as a source of energy for semi-trailer
tractors. These differences need to be considered when making decisions in the
transport business. If some of these differences are exaggerated or, on the
contrary, simplified, this can have a negative impact on repair services, or on
the economic results of the given company or entity focusing on road transport.
Road transport, as well as road vehicle transport, can be defined according to
three basic areas of technical foundations: transport means, transport routes,
and transport equipment, while these three areas are directly involved in the
transport process, and transport means are a specific factor of this type of
transport process. It is because they ensure passenger and freight transport
itself. The basic characteristic of these transport means is their ability to
move. This characteristic distinguishes them from other elements of the
technical foundations of road transport, which e.g., enable or simplify the
relocation process. These are conditioning functions or operations in the design
of buildings or individual devices. For example, these are buildings in which
operations related to transport or equipment enabling cargo handling are
provided.
In its early days, road freight transport was at
a disadvantage compared to railway transport. With the increasing density of
land roads, this ratio mutually developed in favor of
road freight transport. In the past, freight transport was mainly characterized
by the transport of non-expensive and rare items. Mainly construction material
(soil for construction) was transported. However, road freight transport is
currently involved in the transport of food, pharmaceutical, and agricultural
products, the supply of shops, and the transport of semifinished products.
Trucks are the most powerful machines on the road carrying various types of
cargo, from small packages to fuel. The term "utility vehicles"
covers a large group of machines that can be met on and off the roads.
Of course, there are many ways to start a
transport company, and each company may have a different procedure. Operating
companies must have valid necessary licenses, permits and various requirements
of a legislative nature [13-16]. Hence, the operation of a transport company
requires many permits and licenses. The carrier must respect both national
legal regulations and European Union regulations, which are superior to
national law [17-20]. According to the law, it is necessary that the vehicle is
approved for the specified type of transport. The vehicle must meet various
conditions, mainly related to its technical capability, and the technical
condition has been verified at technical control and emission control stations.
All vehicles must be registered in the country for the purposes of obtaining a
traffic license. Nowadays, an entrepreneur has to ensure and comply with many
factors in order to be able to officially operate a transport company, such as:
·
Professional competence: this requirement must be met
by the transport manager, who can be the entrepreneur himself or a person
"connected" with this company. Thus, he must prove a relationship
with the holder of the certificate of professional competence;
·
Technical base: it is a place or space where parking
and possible maintenance of vehicles can be carried out. Of course, space
requirements depend on the number of vehicles and the amount of company
equipment. The approximate area determined for one vehicle is of 60 m2;
·
Transport regulations: it is a document and at the
same time a directive that defines and guides the rules on freight transport;
·
Ownership of vehicles: if an entrepreneur wants to
carry out an activity, he must prove that he is the owner of vehicles. This is
demonstrated through purchase, rental or leasing contracts [21-23].
All the above knowledge indicates that it is
necessary to make the right decision for the purchase of a vehicle, which will
suit the given company the most due to its characteristics. It is for this
purpose that the criteria selection methodology was developed, which arose from
the cooperation of the academic environment with the commercial transport
company Kastrans, Ltd.
2. EXAMINED
TRACTORS
Two
real tractors were selected for a creation of the methodology for the criteria
assessment. There were tractors of Swedish and German producers. The transport
company as well as its employees have already experience with these tractors in
the form of active contact, and drivers really drive them. Figure 1 shows an illustration of the compared tractors.
Fig. 1. An illustration
of evaluated tractors of the Swedish (left) and German (right) producers
2.1. A
description of the Swedish tractor
It
is a two-axle tractor from the Swedish commercial vehicle producer, which
belongs to the German automotive concern. These tractors are among the more
premium lorries on the market compared to the competition. They excel in the
quality of processing, driving characteristics, fuel consumption and
operational reliability. These will be the most important factors in the
evaluation criterion in comparison with the competition. In our case, it is a
tractor model manufactured in 2021, and it had 70,000 kilometers
at the time of evaluation. It is equipped with the largest and most spacious
two-bed flat-floor cabin, which is intended mainly for long-distance transport
and which should provide the driver with sufficient comfort while driving as
well as while resting. The engine has a power of 335 kW (450 HP). It is a
13-liter (13,000 cm3) low-speed turbocharged diesel internal
combustion engine. The internal combustion engine meets the emission standard
EURO 6 NEW [24].
The
chassis is made as a steel frame. It is two-axle, where the rear axle is driven
by four wheels. The front axle is sprung with steel leaf springs. The rear axle
is equipped with an air suspension system that provides suspension and height
control of the rear axle. The wheelbase of the tractor is 3,750 mm. The chassis
also includes fuel tanks with two fuel tanks with the total volume over 1,000 liters of diesel.
The
tractor engine is developed according to the characteristic philosophy of the
producer as a low-speed one. It is suitable for burning 100% HVO fuel, and it
meets the Euro 6 emission standard. Emissions control is ensured only by means
of the SCR system, while the leading Twin-SCR system is available. It ensures
double dosing of AdBlue, and it has a number of advantages, whether the impact
on the environment or engine performance. The unit uses a double camshaft
system to improve gas exchange. This solution contributes to the improvement of
lubrication, cooling, and performance of the turbocharger. The gearbox is an
automatic 12-speed. The differential (a rear axle) is equipped with a lock. The
constant transmission ratio of a distribution box is 2.59. The advantage of
transmission system is, that the operating fluid (oil) is filtered by an oil
cleaner (filter). This ensures more thorough maintenance and thus a potentially
longer service lifecycle [24].
The
service brakes are classical disc brakes on both axles. The brake system is
equipped with the Auto-hold function, which represents a support system for
starting uphill. In the system, it is possible to set ESP and ABS for a
semi-trailer with this function. The parking brake system is electropneumatic,
and it is applied only on the rear axle. The tractor also includes two
additional brakes, a retarder and an engine brake. Their operation can be
controlled automatically or manually by a control switch under the steering
wheel. The main additional brake in the tested tractor is the retarder, which
is 5-position. It is able to provide a braking torque of 4,100 Nm at a speed of
the Cardan shaft as low as 600 rpm.
The
flat floor cabin is among the largest, most comfortable and, in terms of
interior quality, also the best finished. This type of cabin is suitable for
traveling long distances and for a long stay of the driver away from home.
Also, thanks to its interior spaciousness, it is also suitable for comfortable
travel with two drivers. Depending on the equipment, the cabin can reach
different levels of equipment. The specific model has superior interior and
exterior equipment. The interior of the model has wide beds, advanced
infotainment, comfortable air-suspended seats that are heated, and the driver's
seat is also ventilated. There is also independent air conditioning.
The
exterior is also equipped above the standard compared to the basic models. The
air suspension of the cabin, consisting of four bellows, has a very good effect
on driving comfort. The biggest advantage is the LED lighting, which consists
of main headlights, fog lights, daytime running lights, and four powerful
auxiliary lights.
For
the purpose of this research, this Swedish tractor is marked as “SW” tractor.
2.2. A
description of the German tractor
It
is a very popular and well-selling model from the German car manufacturer,
which is owned by a competing German concern to the concern mentioned above.
The tested model has been produced from 1998 to the present. The newest model
generation is available for the presented research, where this vehicle will be
compared with the Swedish tractor described above. This German tractor has many
fans, mainly due to its spaciousness and good ergonomic layout of the cabin
components. Mainly because of this, many drivers prefer it. The producer stands
out for its extensive service network, thanks to which it can promptly respond
to possible vehicle breakdowns practically anywhere, and this is one of the
main reasons why entrepreneurs choose lorries of this brand.
The
compared tractor is from 2019, and to this day, it is still the current and
latest model in the offer of this brand. At the time of the criterion
evaluation, the mileage was 180,000 kilometers. It is
a fifth generation of the tractor with a power of 352 kW (480 HP) and
supercharged by a turbocharger. The transmission of power and torque to the
wheels is handled by a 12-speed automatic transmission. The engine meets the
strictest Euro 6 emission standard [25].
The
tractor does not differ in any particular way compared to the Swedish tractor
described above. It also consists of a steel frame and two axles. The rear with
four wheels is driven from it. The wheelbase is 3,700 mm. The suspension
concept is also very similar, i.e., the front axle is sprung by leaf springs
and the rear by a pair of air bellows. The total volume of two tanks is 1,300 liters. Due to these oversized tanks, the side covers of
the tanks (aerodynamical accessories) cannot be installed, which would improve
the aerodynamics and thus also the vehicle's consumption slightly.
The
Mercedes-Benz tractor engine is designed as an inline engine. It has a
noticeably smaller volume in comparison with the Swedish tractor and the same
number of cylinders, i.e., 6 (-). The engine of the German tractor includes an
EGR valve. In winter operation, it is an advantage that it has automatic active
screens (lamellas) of the radiator, which close and open according to the
engine temperature, thus ensuring a quick warm-up to operating temperature.
However, this system is also not perfect, and the slats tend to get stuck in
bad weather, especially when it snows. This malfunction is then reported to the
driver quite often on the on-board computer.
The
gearbox is an automatic 12-speed one. It includes a single disc clutch. It is
possible to drive on the pre-programmed Economy/Normal/Power driving programs.
The differential (rear axle) is also equipped with a lock. The differential is
provided with active lubrication and its constant transmission ratio is of
2.412. The German tractor is equipped just by one additional brake, and it is
an engine brake. This is a big disadvantage of this particular model because
the engine brake cannot provide as much power as the retarder. For its
effectiveness, it needs to have increased revolutions, and this means that the
automatic transmission must unnecessarily downshift by several gears at once
when braking. This variant is much less gentle on the engine itself, as it
works on the principle of closing the exhaust valves, which leads to greater
requirements for lubrication of individual components. It also has a negative
impact on driving comfort, either through sound effects or uneven or choppy
driving. The engine brake has a power of 410 kW and is therefore classified as
a high-performance engine brake. Service brakes are classic disc brakes,
controlled by air on both axles [25].
The
cabin of the tested model is a flat
floor cabin. It is not among the largest in terms of vertical dimensions. The
interior of the compared tractor cabin looks very modern and, in this respect,
it is very difficult to find competition. Classic exterior mirrors have been
replaced by a camera system, which consists of external side cameras and an
internal pair of large displays on which the image from the cameras is
projected. Moreover, the classic instrument panel was replaced by a pair of
tablets that have premium graphics, excellent readability and easy handling.
Further, the steering wheel contains capacitive surfaces and touch control
surfaces, on the basis of which communication between the driver and the system
is very fast, intuitive and simple.
As
for the interior architecture itself, the German tractor is in the opinion of
the company's drivers more practical and more suitable for resting while
standing due to a break or overall stay away from home. The dashboard is
simple, so the crew feels more spacious. The exterior is equipped with basic
lighting technology, consisting of main xenon headlights and halogen fog lamps.
The suspension of the cabin includes four air bellows.
For
this research, this German tractor is marked as “GR” tractor.
3. EVALUATION
OF TESTED TRACTORS FROM THE DRIVERS’ POINT OF VIEW
Semi-trailers
tractors, mainly when they are used for long-haul transportation, should meet
strict requirements. These requirements relate to more factors. From a driver
and a passenger (a second driver point of view), comfort is one of the most
important [26-28]. Comfort in a cabin of a tractor is influenced mainly by
vibration and oscillation caused by driving on road irregularities [29,30] and
by thermal conditions in it [31].
The
SW tractors of the Kastrans, Ltd. Company are rated
by its drivers as superior and premium tractor with high equipment. From the
exterior side, drivers like the design of the car itself, its exterior lighting
technology and, of course, details such as the side tank covers, tank holders
and all fenders painted in the color of the tractor.
Such accessories are missing from most tractors, and that is why this
particular tractor looks very premium and unusual on the road, and drivers like
that.
According
to the drivers, the interior itself has a luxurious impression. Comfortable
leather seats, which are equipped with heating and ventilation, have a very
good effect on driving comfort, which is only increased by the very size type
cabin. It is the drivers who had the opportunity to try both SW and GR tractors
that see the biggest difference in driving comfort. The SW tractor is
incomparably quieter and more refined. Just the fact that the SW tractor is
equipped with a retarder additional brake compared to the GR tractor makes
every deceleration quieter, gentler and, as quoted, "less kicked and
jerky".
Drivers
who drive the GR tractor like the equipment elements that they would not find
in other tractor units. However, they have certain reservations about it. From
the outside, the car looks modern and aerodynamic. The absence of physical
rearview mirrors only confirms the modern design. However, in terms of design,
the drivers lack the side covers of the tanks, which would complete the overall
design. Of course, they would welcome additional light meters in addition to
the main and fog lights. But their absence is not something that is necessary
for them to drive. According to the drivers, the interior of this tractor is
the biggest advantage. It is well organized and practical. However, long-time
truck drivers are having trouble getting used to the new electronic rearview
mirror system. They would rather go back to classic physical rearview mirrors.
They consider the displays to be poorly readable, unnatural, and the image is
distorted according to them, especially reversing and tight handling are distorted
in the displays.
Driving
the GR tractor is pleasant, drivers like the high seating position and the ease
of use of the on-board computer. When driving on an imperfect road, the
Mercedes gives a "dug and jumpy impression", especially when the load
is unevenly distributed in a semi-trailer. They consider driving in the SW
tractor to be more comfortable and quieter.
4. PROPOSAL OF
THE METHODOLOGY
The
proposed methodology will be suitable for large companies, local private
entrepreneurs, or drivers themselves, who need a system to compare competing
tractors and choose the one that will be more suitable for the buyer according
to the given parameters.
This
system or the method will also be suitable for various publications, where it
will be necessary to compare semi-trailer tractors with each other and draw
different conclusions regarding the properties of the given tractors.
Subsequently, it will be possible to compare them between all existing
mass-produced models. The first step for creating a criterion evaluation system
will be the most fundamental selection of parameters that we will examine and
compare. Therefore, it was decided to divide the given parameters into several
categories as follows:
1.
Features of operational characteristics.
2.
Features of a utility and comfort characteristics.
Among
the operational characteristics of the tractors, the following will be taken
into account:
· Engine power in kW,
· Engine torque in Nm,
· Fuel consumption in l∙100
km-1,
· Distances to service for the
given tractor,
· Service price.
The utility characteristics
of the tractor will include:
· Chassis, cabin and seat
suspension,
· Lighting technology,
· Cabin size,
· Cabin equipment,
· Design and driving comfort.
The
second step of creating a comparison methodology is to assign the given
parameters their importance and express it numerically. This means, more
important parameters will be assigned more weight. Numerical evaluation
of operational characteristics:
· Power of the combustion engine in
kW → 100 points (with the chosen optimal value of 700 kW).
· Torque of the combustion engine
in Nm → 100 points (optimal value 4000 Nm).
· Fuel consumption in l.100 km-1
→ 200 points (optimal value of 15 l∙100 km-1).
· Distance to service for the given
vehicle → 50 points (optimal value up to 5 km).
· Price of the service → 50
points (optimal value up to €2400∙year-1).
· Numerical evaluation of utility
and comfort characteristics.
· Suspension of the chassis, cabin
and seats → 100 points.
· Lighting technique → 100
points.
· Cabin size → 150 points.
· Cabin equipment → 100
points.
· Design and driving comfort
→ 50 points.
If
we consider the sum of the first category, which is equal to 500 points, and
the sum of the second category, which is also 500 points, then the sum of the
maximum achievable points per tractor can be 1,000. This means that a
semi-trailer tractor, which would theoretically be rated 1,000 points is the
optimal choice for its purchase without the negatives present. The description
of the justification for the selection of individual parameters is as follows:
· The power of the combustion unit
- just like the torque of the drive unit, has a fundamental influence on the
driving dynamics of the vehicle.
· The torque of the combustion
engine - with this parameter, dynamic properties are primarily influenced, such
as the acceleration of the vehicle and its speed, especially at the maximum
load of the tractor with a fully loaded semi-trailer. This parameter can be
evaluated in such a way that the higher the torque, the better the dynamics of
the tractor.
· Fuel consumption - it is one of
the most important parameters that should be considered when buying any
vehicle, not only a semi-trailer tractor. The main thing is that today's trend
is the constant increase in the price of fuel, fuel consumption most significantly
affects the cost of operation.
· Distance to the service for the
given vehicle – this factor, as well as other factors, affects the purchase of
a tractor. The driving force is how companies carry out their business
activities, and thereby generate turnover and subsequent profit. Usually, there
is little time to service the cars because the tractors are almost always on
the road with their drivers. Thus, the proximity of the service greatly
facilitates the logistics, the time required, and the costs of the company.
· Service price – each producer of
tractors has a different set length and range of service intervals, and this
directly affects the service price. The criterion evaluation considers the
price of the service for one year of use, or 150,000 km. In this particular
case, there is a paid service contract on the vehicles, which includes
all service operations associated with the vehicle, and thus the price of the
service contract for 12 months will be taken into account.
· Suspension of the chassis, cabin,
and seats - a very important factor regarding the crew's driving comfort and
directly affects it.
· Lighting technology – external
lighting is considered, which the driver uses especially at night and thus
directly influences driving safety from several points of view, such as e.g.,
exhaustion, predictability, and also driving comfort.
· Cabin size, cabin equipment,
design and driving comfort - the bigger the cabin, the bigger the equipment and
the more "premium" the tractor owner chooses, the less problem he
will have to secure the crew, i.e., the driver to the vehicle. Nowadays, there
is a problem with the shortage of truck drivers. That is why this aspect can be
a decisive parameter in how to get a driver.
5. AN
APPLICATION OF THE PROPOSED METHODOLOGY
The
values of individual determined parameters are implemented in two different
tables. Subsequently, evaluation points are assigned to both evaluated tractors
for each parameter separately. A tractor that achieves better results in an
individual parameter receives a greater number of evaluation points. The
evaluation results are implemented in comparison tables. After the subsequent
summing up of all the evaluation points of the individual categories, a more
suitable tractor is determined.
Tab. 1
Quantification of operational parameters of evaluated tractors
|
Features of operational characteristics |
Engine power [kW] |
Engine torque [Nm] |
Fuel consumption [l∙100 km-1] |
Service distance [km] |
Service price [€ per year] |
|
SW tractor |
335.6 |
2550 |
22.4 |
37 |
3480 |
|
GR tractor |
350 |
2500 |
21.6 |
9.8 |
3948 |
Each
parameter is compared with the parameter that was chosen as optimal (rated with
the full number of points, or 100% of the possible rating). Individual
tractors, which will be evaluated with points in the criterion evaluation, will
be more or less close to the ideal evaluation based on the created formulas for
individual parameters. These will be shown as examples in the following points.
They also serve as a guide in the case of implementing other tractors that
someone would be interested in comparing according to this system. Sample
calculations will be shown on the parameters of the compared SW tractor. The
power value was determined by the tractor manufacturer, and then a calculation
was made (1):
(1)
where X
= specified number of points; 700 = ideal parameter value with which the value
of a specific tractor is compared; 100 = the maximum possible number of
points that can be achieved.
The
torque value was determined by the tractor producer and then the calculation
(2) was made:
(2)
where
X = specified number of points; 4000 = ideal parameter value with which
the value of a specific tractor is compared; 100 = the maximum possible
number of points that can be achieved.
The
consumption values of the compared tractors were actually measured on the same
route starting at Address: Tehelná 2, 03601 Martin,
Slovakia and ending at Remusweg 8, 33729 Bielefeld,
Germany (Figure 2), with the same semi-trailer and with a load of the same
weight of 9,000 kg. This route combines urban, non-urban and highway traffic in
approximately the same weather conditions. Therefore, the result of this consumption
test is real, which is carried out in real conditions with one driver and the
same driving style, and thus relatively accurate. When someone wants to compare
other tractors and does not have the opportunity to experimentally determine
the fuel consumption, it is recommended to apply the data from the tractor
producer. To assign points depending on consumption, a calculation (3) was made
as follows:
(3)
where X
= specified number of points; 15 = ideal parameter value with which the value
of a specific tractor is compared; 200 = the maximum possible number of
points that can be achieved.
Fig. 2. The
route of measuring fuel consumption of tractors
The
Kastrans, Ltd. Company headquarters is in the Slovak
village of Žabokreky. The nearest authorized service
from this address is 9.8 km away for the GR tractor. The nearest authorized
service for the SW tractor is 37 km far from the transport company
headquarters. For the possible implementation of other tractors, it is recommended
to use Map Explorer to find out the exact distances of the authorized services
of individual brands. To assign points depending on the distance to the
service, a calculation (4) was made as following:
(4)
where X
= specified number of points; 5 = ideal parameter value with which the value of
a specific tractor is compared; 50 = the maximum possible number of points
that can be achieved. The Kastrans, Ltd. Company has
full-service contracts paid for the vehicles, which they pay with a monthly
fee. As a result, we can determine with maximum accuracy how much financial
resources have been invested in an individual tractor. A monthly fee of 290
euros is paid for the service contract for the SW tractor, which is 3,480 euros
per year. If the company does not have a paid service contract for the tractor,
we recommend summarizing the service tasks according to the manufacturer's service
plan for one year or according to the number of selected kilometers
and having a price offer made for them in an authorized service.
Tab.
2
Summary of obtained points of the group of operating parameters
and evaluation of the suspension
|
Suspension (max. points) |
Front axle (20) |
Rear axle (20) |
Cabin (20) |
Driver’s seat (20) |
Passenger’s seat (20) |
Total (100) |
|
SW tractor |
0 |
10 |
20 |
20 |
20 |
70 |
|
GR tractor |
0 |
10 |
20 |
20 |
0 |
50 |
|
Features of operational characteristics (max. points) |
Total evaluation (500) |
|||||
|
SW tractor |
286.86 |
|||||
|
GR tractor |
307.29 |
|||||
To
assign points depending on the price of the service, a calculation (5) was
made:
(5)
where X
= specified number of points; 2400 = ideal parameter value with which the value
of a specific tractor is compared; 50 = the maximum possible number of
points that can be achieved. The evaluation of utility and comfort
characteristics consists in the fact that, unlike the evaluation of operational
features, individual categories will have their own items and points will be
assigned to them based on their conditions, or the number of points will be
determined using a mathematical formula, where the values of the SW tractor
will serve as a sample.
The suspension
scoring system consists of the following divisions:
· Front axle: if the front axle is
sprung with air bellows = 20 points, otherwise = 0 points.
· Rear axle: if the rear axle is
equipped with 4 air bellows = 20 points, 2 air bellows = 10 points, other types
of suspension = 0 points.
· Cabin: if the cabin is equipped
with air suspension = 20 points, other types of suspension = 0 points.
· Driver's seat: air suspension =
20 points, hydraulic suspension = 10 points, other types of suspension = 0
points.
· Passenger seat: air suspension =
20 points, hydraulic suspension = 10 points, other types of suspension = 0
points.
The
lighting technology scoring system consists of the following divisions:
· Interior ambient night lighting
if it contains = 10 points, if it does not contain = 0 points.
· Fog lights if included = 20
points, if not included = 0 points.
· Main headlights: LED technology =
50 points, xenon technology = 40 points, halogen technology = 20 points.
· Additional lights: each pair
(row) of additional lights is evaluated with 5 points.
Tab.
3
Evaluation of lighting technology
|
Lightning technology |
Interior
ambient lightning |
Fog
light |
Headlight |
Additional
lights |
Total |
|
SW tractor |
10 |
20 |
50 |
5
+ 5 |
90 |
|
GR tractor |
10 |
20 |
40 |
0 |
70 |
Tab.
4
Meaured cabin geometry and cabin size evaluation
|
Cabin size |
Hight |
Width |
Length |
Cabin size |
Hight |
Width |
Length |
Total |
|
SW tractor |
2300 |
2100 |
2060 |
SW tractor |
23 |
21 |
20.6 |
64.6 |
|
GR tractor |
2040 |
2350 |
2040 |
GR tractor |
20.4 |
23.5 |
20.4 |
64.3 |
(6)
(7)
(8)
Tab.
5
Evaluation of cabin equipment, design, comfort
and overall evaluation of utility characteristics
|
Cabin accessories |
Max. points |
SW tractor |
GR tractor |
Design |
Max. points |
SW tractor |
GR tractor |
|
Independent
heating |
20 |
20 |
20 |
Colored front bumper |
5 |
5 |
5 |
|
Independent
air conditioner |
20 |
20 |
0 |
Panels between axles |
Colored = 5 Uncolored = 3 |
0 |
5 |
|
Navigation |
20 |
20 |
20 |
Colored rear mudguards |
5 |
5 |
5 |
|
Adaptive cruise control |
10 |
10 |
10 |
Opinion of two independent drivers |
2.5 + 2.5 |
2 + 2 = 4 |
2.5 + 2 =
4.5 |
|
Seat heating
(driver + passenger) |
5 + 5 |
5 + 5 = 10 |
0 + 0 = 0 |
||||
|
Seat ventilation (driver + passenger) |
5 + 5 |
5 + 5 = 10 |
0 + 0 = 0 |
||||
|
Refrigerator |
10 |
10 |
10 |
|
|
|
|
|
Total |
100 |
95 |
60 |
Total |
20 |
14 |
19.5 |
|
Comfort |
Max. points |
SW tractor |
GR tractor |
Features of a utility characteristics |
Total |
||
|
Driver 1 |
15 |
15 |
10 |
SW tractor |
364.10 |
||
|
Driver 2 |
15 |
13 |
11 |
GR tractor |
263.30 |
||
|
Total |
30 |
28 |
21 |
|
|||
Another
evaluated criterion is the size of the cabin. The height from the center of the floor (between the seats) to the center of the cabin ceiling is measured. The width from the
center of the side window on the driver's side to the
center of the passenger side window is measured.
Further, the length from the center of the front
window to the center of the back wall of the cabin is
measured. The relevant calculations are written by equations (6) for height,
(7) for width and (8) for length. Points for individual parameters are
determined according to tab. 5. Likewise, Table 5 explains the design evaluation.
The evaluation also includes a subjective evaluation of tractors by two
independent drivers, which is also shown in Table 5, which also gives an
overall evaluation of the utility properties. The results of the evaluation are
shown in Table 6.
Tab.
6
The result of the criterion evaluation
|
Total evaluation |
Features of operational
characteristics (500) |
Features of utility
characteristics (500) |
Total (1000) |
|
SW tractor |
286.86 |
367.10 |
653.96 |
|
GR tractor |
307.29 |
279.30 |
586.59 |
6. CONCLUSIONS
The
result of the analysis determined a more suitable tractor for the owner, the
future owner, or the driver. Based on the points obtained in the individual
categories and their subsequent addition, it is determined which of the two
compared tractors is better according to the criterion evaluation. Based on the
data of the research, the SW tractor is more suitable. After consulting with
the drivers of the evaluated tractors and the company's management about the
evaluation results, we concluded that the results are sufficient and that the
criterion evaluation system is professional. This is because the criterion
evaluation was created based on the experience of drivers, owners, and other
responsible individuals in a real transportation company.
Criterion
assessment is created in the Microsoft Excel program. This is a set of
individual tables into which the data are input. Based on these data,
integrated mathematical formulas (equations (1) to (8)) will generate an
individual number of points for a given category and a given tractor. The
resulting values from the tables of the individual features of the tractors
that are evaluated and scored, are calculated based on the integrated links in
the program and generate the final evaluation of the tractors in points. Thus,
it can be said, that the criterion evaluation created in the Microsoft Excel
program is actually a calculation program that, based on the input data,
calculates the required values, either temporary or total. The program is very
easy to use for an ordinary user and the control is intuitive.
Acknowledgement
„Funded
by the EU NextGenerationEU through the Recovery and
Resilience Plan for Slovakia under the project No. 09I03-03-V01-00131.”
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Received 15.01.2025; accepted in revised form 02.04.2025
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