134 apostu radu

SEPTEMBER 2012 VOLUME 7 ISSUE 1 JIDEG 33

Abstract: the purpose for this article is to raise awareness among heavy vehicle manufacturers to the

mistakes that are made in design and ergonomics of their produces. Also, it is an accumulation of needs

that the modern long haul driver has.

Keywords: ergonomics, long haulage, trucking.

1. INTRODUCTION

In the field of road transportation, very important

factor amongst heavy duty truck drivers in choosing a

certain vehicle is represented by the comfort that can be

provided for the user. In spite of the general opinion that

one such job presumes a lowered degree of physical

effort, real situations show the contrary. Truck drivers

that are used to work related issues often accuse both

physical and mental fatigue due to long working hours

and an improper seating position or poor ergonomics of

the entire cabin.

Moreover, it is habit for truck drivers to spend their

free time within the cabin, or even sleeping in the

accommodation provided, thus making the choice of the

cabin critical for the good development of their work

day.

Thus, an thorough study of the problem is necessary,

leading to the following study of their habits and most

common situations faced.

2. COMMON PROBLEMS WHEN DRIVING

First order of business that must be taken into

consideration is the size of the cabin itself. So, once a

complete study of the type of transportation that is

needed to be done with said truck, the cabin will be

chosen accordingly, with the right size and fittings. the

range of cabins on the market vary from short cabs, for

day use, fitted with only two seats and generally with a

raised middle section between the two, to local and

national distribution cabins, which are considered day

cabins still, but which have a small bed behind the two

seats for occasional periods of resting, mainly when the

driver has to spend the night on the road, and needs to

sleep somewhere.

The most common type of cabin is the one used for

international transportation, type of job that implies

driving for long periods of time, generally more that 7

working days is the so called night cabin, which are more

generous in inside space, have two full sized beds behind

the driver's seat and, occasionally purpose made areas for

day to day activities.

Fig 1 Types of cabins available

It is for this type of cabins where the first fault in

ergonomics can be found, more specifically in the middle

section of the cabin that is, in most cases, raised and does

not provide a flat, accessible space.

Such mistakes are made because the main focus

in designing a cabin is to have a low ceiling, which

translates into good aerodynamics which, in result, turns

into good fuel economy.

Such structural modifications have a very negative

effect on the possibility that the driver can adjust the

driving position in correlation to the speed of the vehicle,

road conditions, thus resulting in excessive fatigue and

loss of concentration.

A simple solution for the problem in hand would be

raising the level of the entire cabin floor and shaping its

upper side in correlation to the aerodynamics involved.

Also, some modifications are required to the placement

of the two beds that are generally one above another,

more specifically lowering the two to cabin floor height.

Radu APOSTU

FLAWS IN ERGONOMISC FOR HEAVY DUTY TRUCK CABINS

Flaws in ergonomisc for heavy duty truck cabins


Fig 2 Aerodynamic cabin

Another issue that must be taken into consideration

from the ergonomic point of view, is the placement of the

gear lever, which, in general, is placed directly on the

floor of the cabin too far back for the position of the

driver's seat. This situation results in poor accessibility to

the lever and poor operability, correlated with the need of

frequent use may cause muscular akes along with back

injuries to the driver. These happen especially when

tackling rough road surfaces while having very heavy

loads.

Fig 3 Placement of the gear lever

One solution to the problem could be placing the gear

lever on the central console, which will considerably

shorten the size of the lever and the necessary maneuvers

for operating it. Another big plus of this solution would

be the fact that the driver will have sufficient space in

situations when he needs to move around the cabin or

when taking breaks from work related activities.

Whilst moving, when the driver has to be able to be

focused, he must not be distracted by other elements or

components that he must use. Some switches or buttons,

such as the ones for the radio or CB functions, are flawed

from the ergonomists point of view, because, while

operating, they distract the driver from the main focus,

driving. One of the most frequent operations that a truck

driver does while driving, is operating the CB radio

functions of the truck. This command unit is placed

generally above the windshield on the driver's side.

Along with the movement needed to take the microphone

from it's dock, it generally results in distraction of

the driver from the road conditions, a very dangerous

situation if operating a heavy duty tractor truck.

Fig 4 Placement of the CB radio commands

The simple solution would be integrating such

functions into the stereo system and placing the

commands for it on the steering wheel. This will result in

more space in the cabin, because there will be no more

wires going across the windshield. Furthermore, because

the microphone will be installed in the ceiling of the

cabin, the function cab be used even when the driver is in

one of the beds, resting, without him having to leave the

bed.

These improvements that can be made with minimal

costs to the production of one new vehicle are the most

important ones that can make a difference for the driver

while driving.



3. COMMON PROBLEMS WHILE IDLING

Taking into consideration the periods when the

vehicle is stationary, there are some elements that need

improvements and that will result in lower risks of

injuries and improved comfort.

Fig 5 Resting areas

It is a very well known fact that a well rested driver is

more prudent while driving and is the main focus point

when attempting to achieve good fuel milage. This

means that one of the most important areas for resting

will be the bedding area.

Fig 6 Ergonomic resting area

Nevertheless, manufacturers fail to come up with

efficient solutions for placing and operating the two beds,

that, most of times, are placed one above another and

have folding mechanisms. While for the lower bed big

improvements can not be made, the upper bunk is

generally hard to reach and to get into or out of. The bed

is generally placed at a height of over 1,3 meters and

does not have any system of ladder. A cheap solution,

along with the ease of implementation, would be placing

folding steps into the lateral wall of the cabin, or on the

central console. The space between the door and where

the beds start would be more than enough to

accommodate such steps. As for the central console, the

material of which is built is easily strong enough to

support most drivers. Another very elegant solution

would be making a mechanism to fold the upper part of

the driver's and the passenger's seat to fold and create a

surface that could help with access into the bedding area.

Such simple solutions could greatly reduce injuries that

happen when trying to get into or out of beds and

especially when the driver has not an athletic posture or

necessary skills.

Fig 7 Access to bedding area

Turning the focus on the resting area, several flaws

in design can be found as well. While sleeping, in cold

external weather, the driver needs to stay warm. This is

done with the help of a night heater that generally can be

operated from the dashboard. As a result, the driver has

no control when in bed. The simple solution could be

fitting the cabin with a system that can maintain a steady

temperature, set previously by the user. This way, once

the driver has chosen the right climate for the interior of

the truck, he can rest without having to adjust according

to outside temperature's variations.



Another problem while in bed for the driver is

operating the stereo system of the truck. It is a

pleasurable way of spending one's free time, and drivers

often fall asleep in their beds with the stereo turned on.

The most simple solution to this problem would be fitting

the cabin with a remote control for all de functions such

as radio, navigation or illumination.

Another area where the heavy duty truck driver has to

operate is in the close proximity of the truck, where they

must be able to reach storage spaces for tools and

auxiliaries.

They have to do daily checks to the tires, semi-trailer,

body of the truck, oil or couple semi-trailers.

Fig 8 Acces to storage spaces

In some cases, these storage spaces are placed

between the steps made for accessing the cabin. These

steps are made from steel and are very deep into the body

of the cabin. This results in very small angles for

accessing she storage spaces. The ideal solution for this

problem could be placing storage spaces far back in the

southern body of the truck, as access panels that can be

operated both from outside the cabin and from the inside.

A mandatory requirement for these storage spaces would

be to never exceed the average driver's shoulder's height

of 1,5 meters.

4. CONCLUSIONS AND DISCUSSIONS

Different Positions of a manikin inside the cabin

are shown in the picture below:

Fig. 9 Manikin sitting positions

The figure 9 [1] shows the driver in sitting position

while driving. The manikin, that was chosen for the

analysis is of 50th percentile. The data those were

considered are of drivers anthropometric data.The upper

berd can be folded at that time and thus four people can

sit in the cabin including driver. The figure 10 [3] shows

the sleeping position of the people in the cabin.

Arrangement for sleeping is made for two people. There

are two beds, lower bed and upper bed. The upper bed is

hold by chain hanging from the top.

Fig 10 Manikin sleeping position

REFERENCES

[1] Dalela, S. (1999). Text Book of Work Study and

Ergonomics. University of Roorkee, Roorkee. 5th

Edition.

[2] Hedge, A. (2000). RULA Assessment worksheet.

Cornell University. Ithaca, NY.

[3] Bots, H., Buffinga, J. (2000). Design Patterns in

Automotive Design: A Behavioral Study. Technical

Report IDE 350.

Author:

Radu Apostu Master student at the Faculty of Aerospace

Engineering, Descriptive Geometry and Engineering Graphics

Department, Bucharest. Email: [email protected]

134 apostu radu

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