The Ergonomics of

Driving
BY DR/ KHALED ALSAYANI
There are four good reasons why we should expect the high prevalence of back
pain which we encounter in drivers:
 (i) Drivers may spend considerable periods of time in a fixed posture with
relatively little opportunity for fidgeting.
 (ii) The driving position may be less satisfactory than other sedentary working
positions-particularly with respect to the degree of spinal flexion required.
 (iii) The driver's back is exposed to vibration and impact, and to dynamic
stresses during acceleration, deceleration and cornering.
 (iv) Driving may also involve long periods of intense concentration and may be
psychologically stressful (at least for some people
 Driving Statistics

• On average men drive 71 • One study analysis for

kms, women drive 55 the possible reasons
kmseach day related to reporting of low
back pain found:
– Long-term vibration
• Studies have found exposure from driving
significant associations among the HIGHEST risk
between driving and factor for neck, back and
back problems. low back problems.
 Problems with Frequent Driving

• Neck, back and shoulder pain

• Cramps, pressure points & poor circulation
in the legs & buttocks
• Immediately after driving – increased
chance of low back injury from lifting
• Long-term potential for degeneration of
spinal discs and disc herniation
What Activities Increase Risk?
ACTIVITY RISK
Driving 30 km or more Two to four times risk of back
a day pain
Truck Driving Four times risk of disc
ruptures
Car Driving Two times risk of disc ruptures

Increased Vibration Increased tension, fatigue,

pain
Driving a bus Back pain risk increased

OHS Canada, Oct., 2000

 Who is at Risk?
• Truck drivers / Ambulance Drivers
• Heavy equipment operators
• Bus drivers
• Forklift operators
• Farmers
• Delivery and courier service workers
• Taxi / Limousine Drivers
• Travelling sales workers
 Back & Neck Injuries

• Two main hazards

– Sitting for long periods of time
– Whole-body vibration
 SITTING Hazards
• An AKWARD posture
• A STATIC posture
• A WORKING position
• Hard on DISCS & LIGAMENTS of the
back
• Restricts BLOOD CIRCULATION through
the muscles = fatigue
Posture and Lumbar Load
 Long Term Sitting

• Sitting is a static posture

– BUT not void of muscle
contraction
• BUT, only some muscles
NOT all – therefore, some
muscles work constantly,
while others do nothing!!
Backrests (Lumbar Supports)

• Sitting flattens lumbar curve

– Changes biomechanics of
spine
– Increased forces on discs
– Increased length of ligaments
– Increased muscle tension

• Need support for curvature

Whiplash Injury

 Whiplash injury occurs in a rear end collision-typically when a stationary

vehicle is "shunted" from behind, taking the driver unawares. The impact is
transmitted (through the back of the seat) to the driver's trunk and shoulders,
which accelerate forward. The inertia of the head causes an initial forceful
hyperextension of the neck-which is followed by a flexion phase as the head is
catapulted forward.
 t is in the initial hyperextension phase that the principal injuries
characteristically occur:
 these may include disc lesions, damage to the anterior longitudinal ligament
of the spine, various vertebral fractures and muscular injuries (particularly of
the sternomastoid).
 There are sometimes signs of concussion, due to movements of the brain in
the cranial cavity.
 Whole-Body Vibration
• Transmitted through the back & buttocks when sitting
• Every object has a ‘resonant frequency’ (RF) 3-5 Hz –
vibration from the road is often in the body’s RF range;
this increases the risk of injury
• Long-Term exposure:
– Disc displacement
– Degenerative spinal changes
– Lumbar scoliosis
– Intervertebral disc disease
– Herniated discs
– Disorders of gastrointestinal system
 Reducing Effects of Vibration
• Reduce transmission
– Improve vehicle suspension
– Maintain equipment properly
– Proper engineering of seating
– Use of materials that generate LESS vibration
• Decrease amount
– Reduce speed of travel
– Increase rest/recovery time between exposure
– Alternate tasks to minimize vibration exposure
 Reduce – cont….
• Modify the seat and control positions
– Back rest support
– Reduce forward/sideways leaning of trunk
• Eliminate awkward postures
– Difficulty seeing displays or reaching
• Reduce or isolate from the vibration
source
– Seated – spring or cushion (as an isolator)
Manual Handling
 Selecting a Vehicle
• Does it match requirements for the body size of the
driver(s) & any physical limitations
• Do the layout & ergonomic features of the vehicle meet
your needs?
• How much time per day does the driver use the vehicle
and what distance do they drive per year?
• Does it have features that assist in the kind of work the
driver does – eg. Easy to load trunk (salesperson)
 Ideal Car/Cab Design

• Adjustable seat back incline (100o)

• Changeable seat bottom depth
• Adjustable seat height
• Adjustable seat bottom incline
• Seat cushion with firm (dense) foam
• Adjustable lumbar support
• Adjustable bilateral arm rests
• Adjustable head restraint
 Car Seat Design – cont…

• Seat shock adsorbers to dampen

frequencies between 1 – 20 hz.
• Linear front-back seat travel to allow
differently sized drivers to reach the
pedals
• Seat back damped to reduce rebounding
of the torso in rear-end impacts
 Car features: Seat Base
• Adequate leg length
– Ensure thighs are adequately supported
A
• Picture A – too short
• Picture B – too long

• Adequate height adjustment

• Feet can operate pedals without
stretching
• All controls are easily reached
• All display instruments can be B
seen
• Good all round vision
 Car features: Back Rest
• Ensure the height of the back rest reaches the shoulders
and does not obstruct ‘rearward vision’

• Ensure the back rest width is enough to

support the shoulders
Car features: Steering Wheel
• Adjustable steering wheel – in/out, up/down and
tilt
• Power steering
• Centrally positioned and not ‘off-set’ to prevent
rotation of the spine
• Ensure steering wheel does not obstruct the
display panel
 Steps to Injury Prevention

• Learn how to get in and out of vehicle

• Use a good sitting posture – use lumbar support
• Tilt the backrest to 110 degrees from you legs to reduce
disc pressure
• If possible, tilt the seat a notch or two back and forth
every 20-30 minutes – alters the direction of vibration
• Adjust the steering wheel – ensure you can press the
pedals without moving your low back off the back of seat
• Avoid slouching
• If possible, change positions while driving
 Steps to Injury Prevention

• Adjust your headrest

• Adjust your armrests
• Check your hand position on the steering wheel
• Try to take regular rest/stretch breaks. Only 5 minutes
will suffice
• Avoid lifting immediately after driving – give yourself on
or two minutes to stretch and rest before lifting
 Working from your vehicle

• Working from a vehicle can entail use of a

laptop, general paperwork, mobile use or
manual handling. This could involve:
– Static and awkward postures
– Twisting and leaning to one side
– Leaning forward
– Slouching
Best location for a computer
• A & B – poor body
postures &
increased muscle
strain
– Increased muscle
fatigue
– Increased risk of
low back pain
– Increased risk of
shoulder MSDs
Devices for laptop use
Human Factors & Driving

• Speeding
• Fatigue
• Distracted Driving
 Speeding

• Safety features can be breached once

drivers pass certain speed thresholds
– Antilock braking systems (ABS)
– Brake assist
– Electronic brake-force distribution (EBFD)
– Electronic stability control (ESC)
• Fatigue can be experienced for a variety of
reasons:
– Inadequate sleep
– Alcohol / medications
– Prolonged hours driving
– Time of day
• At risk for ‘nodding off’ at the wheel
• Slower reaction times
• Reduced overall attention
• Slower decision-making
• Delayed information processing
• Fatigued drivers not very good at gauging their
own fatigue level
• Car safety features become ineffective
(similar to speeding)
 Distracted Driving
 Fatal collisions where distraction is cited as
cause have risen by 17% in Canada from 302
deaths to 352 from years 2006-2010
 Studies estimate that distracted driving accounts
for 30-80% of collisions – cellphone use
 Distracted Driving (CAA)
• Cell phones are the most common distraction
• Texting – 23 times more likey to be involved in a
crash or near crash event compared with non-
distracted drivers
• 84% of distracting-driving-related fatalities in US
were tied to the general classification of careless
or inattentiveness
• 80% of collisions and 65% of near crashed have
some form of driver inattention as contributing
factors
 Distracted Driving (CAA)

• Distracted drivers are 3 times more likey to

be in a crash than attentive drivers
• Driver distraction is a factor in about 4
million MVA in North America
 Cell Phone Use

• Bluetooth
• Hands-free car kit