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SASTECH 47 Volume 8, Issue 2, September 2009

Interior Design of Long Haul Truck Cabin for Improved Ergonomics and Comforts

Kishor Powar1, Sukanta Majumdar2, Prakash Unakal3

1 - M. Sc. [Engg.] Student, 2 - Assistant Professor, Product Design Centre, 3 - Professor and Head, Department of Design, M.S. Ramaiah School of Advanced Studies, Bangalore 560 054

Abstract

The project was to design of a truck cabin for improved ergonomics and comfort for driver in Indian driving condition. The focus was kept on the psychological and behavioral pattern of Indian drivers along with the Ergonomic issues. Driver’s comfort is not even a factor in existing Indian trucks. Driving a truck in Indian condition such as the condition of roads and other factors are not up to the standard. Driving throughout the day in such conditions leads to physical and psychological deterioration of drivers. This may even lead to accidents. So it was important to design the interior of a cabin of a truck considering ergonomics, comfort and aesthetics for existing driving conditions in India. There is a wide scope for new modern style interior design of truck cabin for Indian market.

Gemba study and product survey were done to understand the problems of existing market. It was concluded from these studies that the cabin of the truck is like the interior of a home. There was a need to include various types of accessories to the dashboard for comfortable and enjoyable driving, a proper storage system of water and cooking stove as well as a foldable bedding system for two persons. PDS was generated after understanding the needs of drivers those were converted into technical voice through QFD. Concepts were generated according to PDS. Concepts were represented by hand sketch and Photoshop tool. The final concept was selected based on the present trend and the requirements of driver. The detail design of interior of the truck cabin was made by using CAD tool i.e. CATIA V5 R16. Digital model for the final concept was rendered using Hypershot 1.5 software with all the detailing of the cabin interior parts. Scaled mock-up model for the same was made for visual inspection.

Finally the design was analysed by RULA analysis method using “Human Activity Analysis” module of CATIA V5 R16 software was done to confirm the positions and dimensions of all the features in the truck cabin.

Key Words: Interior Design of Truck Cabin, Ergonomic Study of Driver Seat, New Modern Style 1. INTRODUCTION

Automobile styling has had an important impact on the world-wide economy during the past century and millions of additional vehicles have been sold because of it. Much research has not been done in automobile interior design in comparison to fine art or other commercial or industrial arts. However, automobile design affects the journey of millions of passengers to a greater degree, ergonomically, economically and culturally than many of the other subjects. The task of the design team is usually split into three major aspects: exterior design, interior design, and color & trim design.

A long haul truck (figure 1) is designed to haul for long distances and is equipped with an ample cab hosting from a simple bed to almost a full house amenities like bed, toilet, TV, audio system, air-conditioning and kitchen etc.

Fig. 1 Long haul truck Interior equipments in long haul truck generally include dashboard, passive safety, shifter for selecting gear ratios and ancillary. It also includes ancillary equipment such as stereos, air conditioning, phones, global

positioning systems, cup holders, refrigerator, console boxes etc. 2. PROJECT METHODOLOGY

Fig. 2 Project methodology flowchart

In this project of truck cabin interior design, market study, literature survey and user study were done to understand the existing problems of the users, market segments and demand in the present market. Silent observation method, informal interview techniques, participatory approach, questionnaire survey were done to collect the data about problems of the users of trucks.

One full scale ergonomic model of the interior of cabin was constructed to conduct the survey in ergonomics. Also one of the existing interior of cabin of a truck was selected for benchmarking. In this case, TATA Novus was selected as the benchmarked product


for cabin interior design. Product Design Specification was set after a detail study of literature and analysis of problems.

Many concepts were created with detail design according to the design criteria and one of them was selected for final simulation of human activity analysis, digital and physical mock-up model. The total process is documented in figure 2.

3. LITERATURE REVIEW

In the new millennium, demand of trucks and

freight transport will be manifold due to economic growth and infrastructural development in India. Improved transport efficiency and low costs will derive the criteria like safety, ergonomics and environmental properties in design of cabin interior of truck.

Fig. 3 S-Curve for trucks

It is clear from the s-curve (figure 3) that only after 1980’s major focus in design of truck was shifted to environmental issues, ergonomic issues and comfort of driver.

4. MARKET RESEARCH

To design the interior of a truck cabin for Indian

markets it is necessary to benchmark the trucks available in the Indian market.

Fig. 4 Tata Novus truck interior TATA Novus truck (figure 4) comes with

unbeatable features those make the interior of the cabin most pleasing and provide ample driver comfort. The TATA Novus Tipper appreciates that driver comfort is

foremost, especially with the long hours of driving involved. With these and other features for comfort, ergonomics, safety and drive assisting, the TATA Novus sets new benchmarks on the Indian roads.

Fig. 5 Volvo truck interior

Volvo Truck cabin interior (figure 5) was designed to create a work environment with optimum function, space and comfort, based on the results of several studies among drivers and haulers. Besides space, comfort and smart storage solutions, it gives the driver a bright, attractive environment, which can make driver’s work easier and more efficient.

Fig. 6 Avia Ashok Leyland truck interior

Fig. 7 Mercedes truck interior Ashok Leyland, the flagship firm of Hinduja

Group plans to bring out Avia D series trucks (figure 6) to India by 2010-11. Currently, the D-line series are marketed in Czech Republic, Hungary, the UK, Ireland and Spain from the head quarter of Avia Ashok Leyland Motors in Prague. The acquisition of Avia by Ashok Leyland Motors in 2006 is expected to have a good quality product in Indian market. It is the first Indian


company to have a truck manufacturing unit in Europe. Survey conducted by Ashok Leyland showed that customers want both safety and comfort while covering long distances which made them design these trucks.

The relaxed working environment and comfort make this cabin of Mercedes truck (figure 7) ideal for long-distance haulage. Standard-fitted comfort suspension seat, multifunction steering wheel, air conditioning and spring-core mattress, A level floor throughout, ample room to move around and generous stowage compartments and shelves, ideal also for two-person crews. 5. USER STUDY

Silent observation method, informal interview techniques, participatory approach, questionnaire survey were done to collect the data about problems of the users of trucks in Indian context. Photography was done to grab the different activities of the driver and the assistance within the truck cabin. The activities of driver and cleaner were observed. Some of the common activities were documented. After documenting different activities of driver, inferences were made that some extra facilities must be designed with some refined design of existing facilities in the existing cabin of the truck to assist the driver for comfortable driving for long hours. Areas such as driving area, water storage, sleeping arrangement, cooking, storage space for cooking utensils, switch panels, mobile charging, dial indicators, storage space to keep belonging etc. were addressed in this project. The observation made was as follows: No water storage facility is provided in any truck cabin in Indian Market. This was a commonly observed problem in almost every truck. Generally water is stored by the driver using cans, barrels, utensils etc. Even Volvo truck does not have any provision for water storage.

Enough space is provided for sleeping purposes in the truck. Sleeping arrangements in most of the cabins are in good condition; but in some cases, the arrangement is made for only one person, where as there are more than one person travel in all these trucks.

There is an essential need of safe arrangement of cooking in the cabin, because many of the drivers use to cook by their own and they have their own arrangement for cooking inside the cabin, which is not safe (figure 8). They use kerosene oil stove for cooking purposes within the cabin. Over all it costs less in comparison to buy food from any shop. And also they do not have proper storage area to keep those cooking utensils. Mostly they keep those cooking utensils under the bed.

Fig. 8 Cooking activity inside the cabin It was observed that, most of the drivers use

wooden stand below the accelerator, clutch pedals, which give enough support to their feet while driving

and also protect their feet from heated floor. It provides comfort while driving for a long distance.

In many cases, switches are placed in awkward positions; sometimes they are away from reach of the drivers when in sitting position. Drivers have to stretch their hands when they want to operate those switches.

Most of the drivers use mobile phones. But there is no mobile charging facility inside the cabins. The drivers use to make their own arrangements for charging purposes of mobile phones. No mobile phone holder is provided on the dashboard of any truck; so the drivers place their mobile phone at any place in the cab or they keep it in hanging position.

There is no proper place to keep their daily belongings inside the cabin. They are placed anywhere within the cab. Instrument panel and other display systems in the driver’s field of vision are sometimes obstructed by the steering wheel. Dial indicators are not positioned properly. Both dry and wet cloths are hanged over a rope as there is no proper place to keep them. 6. PROBLEM DEFINITION

Driver’s comfort is not considered as a deciding factor in design of Indian trucks. Driving condition in India such as roads and other factors are not good. Driving throughout the day in such conditions leads to frustration in drivers which may lead to accidents. So it is important to design cabin interiors considering ergonomics, comfort and aesthetics for drivers in Indian driving conditions.

6.1 User Feedback Analysis Process • 91 trucks of different make and from different

parts of country were considered. • 91 truck drivers from north, south and west zone

respectively were interviewed. • There were total 20 questions in the form of

questionnaire given to those drivers. • The feedback results were divided into North,

West and South zone of India. • Feedback from each zone was separately analyzed

for conclusions. • Feedback results were used to plot bar charts to

clarify the situations.

Fig. 9 QFD results 6.2 Quality Function Deployment

The QFD was done to convert the voice of

customer into technical voice. Results of the QFD


process done is as shown in figure 9 below. Result shows the priority of the technical voice.

7. PRODUCT DESIGN SPECIFICATIONS

Product design specifications were decided according to the collected data (figure 10).

Fig. 10 Product design specification

8. ERGONOMIC STUDY Ergonomic aspects were considered to decide the

dimensions of every part of cabin design for cognitive and physical activities for truck drivers (figure 11 & Table 1). 8.1 Defining Work Zones In order to do define workspace a full scale physical model was made. The purpose of modeling was as follow. • To get clear idea to locate the features in the cabin. • To define the work zones according to the usage of

features. • To make use of anthropometric dimensions while

designing the interior of truck. • To modify the dimensions if it is not correct. • To get realistic feeling from user point of view.

The purpose of arranging tools or features around the cabin was to minimize the distance of reach for the driver at the time of driving. The work space was divided into three zones shown in figure 12, for the above purposes as:

Primary work zone - The distance from elbow to hand. This zone includes things those one touches on a daily basis.

Fig. 11 Various human postures Secondary work zone - Within arms reach. This

zone is used to position those items those one uses frequently, but not all the time.

Reference zone - Outside of arms reach. This zone is use for least used items.

After setting the work zones, it was clearly known which feature come in primary zone, secondary zone and reference zone. Features such as steering, switches, gear, mobile etc. which are used by the driver


frequently come in the primary zone. Other features such as AC control, audio system, cup holder, etc. come in secondary zone.

Remaining features which are not used regularly comes in reference zone.

Table 1 Indian anthropometric dimension

Sl. No Parameters Percentile Design

Method 5th 50th 95th A Normal Sitting 757 819 893 ED B Eye 678 738 805 AD C Lower Lumber 72 101 156 AD D Mid Shoulder 510 576 634 AD E Elbow Rest 158 213 270 AdD F Knee 472 519 567 ED

G Vertical upward arm reach from mid shoulder

623 701 774 D

H Popliteal 380 425 471 AdD

I Buttock to Popliteal length 399 455 512 AdD

J Vertical upward area reach from seat surface

1199 1315 1414 D

K Vertical upward arm reach from floor

1611 1713 1821 D

L Buttock to leg length 640 719 779 AD

M

Buttock to extended leg comfortable length

758 923 1086 D

N Bi-deltoid 379 426 482 ED O Waist 216 259 317 ED P Span 1549 1684 1829 D

Q Upper position length 469 629 799 D

R Mid position length 749 849 939 D

S Lower position length 419 599 769 D

T Upper position length stretched 839 1099 1399 D

U Mid position length stretched 1069 1349 1619 D

V Lower position length stretched 879 1129 1439 D

W Grip inside diameter, maximum

42 49 56 AD

X Hand breadth with thumb 86 99 111 AD

Y Hand breadth without thumb 72 81 90 AD

Z Hand length 163 180 198 AD AD - Average Design ED – Extreme Design AdD - Adjustable Design D - Design for 5th Percentile 9. CONCEPT GENERATION

Concepts were generated by observing and collecting data of truck interior style since late 1980’s. Interiors of other vehicles were also considered. Shape, texture, fabric, color etc. were the major areas while generating the concepts. Each feature was separately designed and finally all were merged together (figure 13, 14, 15, 16, 17& 18).

Fig. 12 Work zones

Fig. 13 Concept 1

Fig. 14 Concept 2

Fig. 15 Concept 3


Fig. 16 Concept 4

Fig. 17 Concept 5

Fig. 18 Seat concepts 10. HUMAN ACTIVITY ANALYSIS

Different Positions of a manikin inside the cabin

are shown in the picture below:

Fig. 19 Manikin sitting positions

Fig. 20 Manikin sitting backside The figure 19 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 Indian anthropometric data. Two people can sit in the back side of the cabin as shown in the figure 20. The upper berth can be folded at that time and thus four people can sit in the cabin including driver.

The figure 21 shows the sleeping position of the people in the cabin. Arrangement for sleeping is made for two people. There are two berths, lower berth and upper berth. The upper berth is hold by chain hanging from the top.

Fig. 21 Manikin sleeping position

10.1 Vision Analysis It is important to have clear comfortable vision at

the time of driving. One needs to be able to judge distances, read road signs, look at the rear view mirror and traffic lights. Also one must responds to changes in environment quickly and efficiently.

Fig. 22 Vision window

The figure 22 shows the binocular vision of a truck driver. The middle zone represents the line of sight. It is clear from the analysis that the instrument panel and the


rear view mirror are within the line of sight of driver. So it is concluded that the position of instrument panel and the rear view mirror is correct dimensionally in the design. Instrument panel can be clearly seen through the steering frame in the new design. This indicates that the display system within the driver’s field of vision is not obstructed by the steering wheel. 10.2 Reach Analysis

A reach envelope is a three dimensional surface

that represents all the possible positions of the required features the manikin can reach using only the arm and forearm. The blue color zone in the figure 23 represents the reach envelops of left arm and right arm of the driver.

The figure 23 represents the reach of right hand of driver. The reach envelop indicates that the right hand of driver can reach all the controls on the door and switches on the right side of dash board. The figure 23 represents the reach of left hand of driver. The reach envelop indicates that the left hand of driver can reach all the controls such as AC control panel, audio system, mobile, cup holder, gear etc.

Fig. 23 Right and left hand reach 11. VALIDATION OF FINAL CONCEPT

Design of interior according to the exterior (figure

24) is a good trend in automobile industry. The same idea was followed in this project also.

Fig. 24 Concept truck exterior The figure 25 shows the sectional view of the truck

cabin; this gives clear idea of exterior and interior of truck cabin. The interior matches with the exteriors to create a sense of New Modern Style in design.

Fig. 25 Truck cabin section At the time of designing the interior, the focus was

kept on the positioning of the features, fabrics, colour combination, feature colour based on their functionality.

Fig. 26 Truck interior front side

Fig. 27 Truck interior view Figure 26 & 27 show the interior design of the

cabin of truck. The interior gives a spacious feeling. The dimensions of the cabin were according to Indian standard. Dark blue and yellowish cream colours were chosen for the interior. It creates a high contrast in the composition. The light cream colour adds the softness to the strong masculine effect of dark blue to create the modern look of the interior.


Fig. 28 Truck interior back side At the back of the cabin there are two berths for

sleeping as shown in the figure 28. The upper berth is hold by chain. One water storage tank was installed at the bottom left hand side of lower berth for general usage. At the right hand side there were vertical storage compartments for keeping the belonging of driver. Also there is a first aid box and drinking water can at the right side as shown in figure 27. At the bottom of right hand side there is a compartment to store cooking utensils. Thus all the basic features were provided in this design.

12. CONCLUSION

The interior design of truck cabin gives the feeling of home interior. The New Modern Style was introduced in this interior design with simple straight

line composition and a combination of dark and light colours. Some of the basic facilities were provided in this long haul truck cabin according to the demand of Indian life style of drivers for their comforts.

All the ergonomic consideration were included in design and validated by software analysis.

The future scope of the design can be in the direction of eco-friendly material and sustainable manufacturing.

REFERENCE [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.

[4] Mangus, R., Taylor, D. (2005). Auto Interiors. California Bill‘s. 2nd Edition.

[5] Chakrabarti, D. (1997). Indian Anthropometric dimensions for Ergonomic Design Practice. National Institute of Design, Ahemdabad.

[6] Reed, M. P. (2007). Driver and Passenger Ergonomics. PhD Report. The University of Michigan. Ann Arbor. Michigan.

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