Vehicle Safety Systems

11-12 September 2009SECC and Glasgow Science Centre

The UKRO authorises the use of the educational information contained within this document,

however reference must be given to UKRO with the use of the UKRO logo

www.ukro.org

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1. Introduction

The aim of this document is to provide current (2009) information in relation tomodern day car safety systems, and the difficulties such systems pose for the UK’sProfessional Rescuers. We will consider the influences of:

Primary Safety Systems - systems that are being included to avoid the vehiclebeing in a crash.

Secondary Safety Systems - systems that aim to reduce the impact of a crashupon its occupants.

The information contained within this handout is being made available through theUKRO and its partnership organisations. Should you wish to receive furtherinformation please contact Dick Dawson who is part of the UKRO EducationCommittee (ddawson@ukro.org)

2. Why Do Safety Systems Exist?

In the UK there are 2,700 deaths, and 30,000 serious injuries associated with car collisions, reported each year. Although these figures are a stark reminder ofthe dangers which face the average car user, there are number of more powerfulinfluences which dictate what systems are manufactured into the modern vehicles.

• Consumers demand safer vehicles for themselves and their families, and it istheir sales pattern that dictates the success of manufacturers

• Manufacturers gain additional marketing value, by introducing systems to beatcompetitors and win additional consumers.

• Governments legislate not only for responsible driving e.g. penalties for drink driving and drug abuse, speeding etc, but stipulate a requirement forbasic safety systems e.g. seat belts, in an effort to reduce the burden of cost on society associated with casualties involved with car collisions.

• Premium loadings on vehicle insurance by large insurance bodies in relation tocost of damage/injuries by vehicle type e.g. 85% claims relating to personal injury are for Whiplash injuries.

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3. Primary Safety Systems

Technology that helps to avoid/prevent a crash from occurring

New technologies now coming forward will have a significant effect on the way thepublic view crash safety — with cars being able to avoid or mitigate (reduce) thelikelihood of a crash occurring in the first place. Primary systems focus purely onthe need to prevent the vehicle when mobile from being involved in a collision:

a. Electronic Stability Control (ESC)b. Adaptive Cruise Controlc. Lane Departure Warningsd. Driver Alert Systemse. Night Vision with Pedestrian Detectionf. Low Speed Avoidance Systems

Electronic Stability Control

Over 3,000 young drivers aged under 25 are killed or seriously injured on UK roadsannually. One of the biggest accident types for young drivers is single vehicleaccidents involving loss of control. ESC a system designed to apply braking toindividual wheels aims to help prevent a skid or spin.

New and young drivers most commonly drive small cars that are cheaper to buyand to insure. Small cars are less safe because of their size. Small cars are alsoless likely to have ESC fitted as standard, which is a vital safety feature. A first caris often second hand, which makes it even more difficult for young drivers tochoose a car fitted with ESC. Yet these young drivers are most likely to be involvedin the type of loss of control crashes where ESC could help to prevent the crash.

Young people drive poorly equipped cars.

Research centre, Thatcham have undertaken on behalf of the UK insurancecompanies an assessment of vehicles being produced for the UK’s roads. Thesefitment ratings show there are only 5 supermini models with ESC fitted asstandard. These are the Mini Hatch, Mini Clubman, Peugeot 1007, Smart For Two,and the Suzuki Splash. From the 47 supermini models rated, these represent only11% and only a very small choice for the buyer.

Department for Transport research data has shown that vehicles equipped withESC are 25% less likely to be involved in a serious or fatal crash. Currently, ESC isfitted as standard on only 53% of new cars on sale in the UK today. The systemcosts on average £425 to fit as an option, but the cost of the components is wellunder £100, so why don't all vehicle manufacturers fit it as standard? New

regulations will see that all vehicles manufactured from 2010 onwards will have tobe equipped with a system for ESC.

It is estimated that such systems will reduce the number of serious crashes andcontributes to improved road safety by:

• 380 fewer fatalities in the UK annually• 1,100 fewer serious injuries• 7,800 fewer crashes overall.

Adaptive Cruise Control

Adaptive Cruise Control is a system that links the common cruise control systemwith a 77 GHz radar fitted at the front of the vehicle. Essentially a comfort feature,ACC allows the driver to pre-set a speed in changing traffic conditions, with thevehicle autonomously. This system maintains a safe distance between itself andthe vehicle it is following,whatever the speed of theprevailing traffic. The latestgeneration of these systemshave full stop/gofunctionality, your carcoming to a complete stopwhen its path is blocked.The car will then start moving again once traffic conditions allow, thus alwaysmaintain a safe distance.

This system can also incorporate the Collision Mitigation Braking System which willwarn the driver visually and audibly that a potential collision is imminent. in somecases, the system will apply up to 70% of available braking power in an attempt toavoid or mitigate the crash. Many systems will pre-charge seat belts, airbags andbrake systems to obtain optimum performance in the event of a collision. The ACCsystems are not a set and forget system, in so far as they do rely on the driver topre-set the controls for speed preferred and to monitor the vehicle at all times.

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Lane Departure Warnings

This safety system aims tokeep a moving vehicle withinlane marking on the road andhelp protect the occupants ifthe driver is distracted ortired. The system operatesbetween 45-112mph andprovides a continuouswarning beep when the car isabout to cross the roadmarkings.

If there is no response fromthe driver the system takescontrol of the electric powersteering and calculates the optimum steering torque to keep the car in the centreof the lane.

It should be noted that such lane keep assist systems are not there to drive thevehicle, and to prevent abuse of the system it will switch itself off if the drivertakes their hands off the wheel for longer than a few seconds. It is not there toreplace the driver completely. Additionally, the system does not intervene if theindicators are used or if positive steering movements are made.

Driver Alert Systems

With the increasing use ofvehicles on britains roads, andlonger journeys being made,accidents due to driverdrowsiness are a commonoccurance. A number of vehiclesnow incorporate a ‘Driver Alert’system which monitors theactions of the driver and giveswarnings that their physicalcondition may have an adverseeffect on their ability to react toroad situations.

Volvo Driver Alert System

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Some systems use a camera locatednear to the rear view mirror to monitorthe driver, other systems monitor thedriving behaviour for patterns duringthe first few minutes of every journeyand then compares ongoing drivingagainst this pattern. Warnings are activeon systems from 40mph upwards to113mph.

Night Vision with Pedestrian Detection

BMW have recently introduced to a number of their vehicles a safety system toprevent vehicles impacting on pedestrians in the dark. The systems have beentested with other heat signatures such as those from animals in roadside fields etcand has proved very accurate.

It should be noted that suchsystem need not be used inisolation and manufacturers will belooking to package all safetysystems to ensure that the vehiclehas the greatest opportunitiesavailable for crash avoidance.

Low Speed Avoidance System

In an effort to prefent low speed collisions and impacts with pedestrians, a numberof vehicle manufacturers have designed and integrated the autonomousemergency braking system. This system prevents the car from coming into contactwith other objects during low speed travel. This is a represents a major step in thefuture of accident and casualty reduction on UK’s roads.

One system currently on the market is Volvo’s City Safety system. This uniquesystem is designed to chiefly address the most common crash type, the low speed“fender bender”. Typically occurring at speeds below 20mph these accidentsrepresent 75% of all crashes and such a system fitted to all cars could significantlyreduce whiplash injuries and repair costs. This system uses low cost laser radar

Mercedes Attention Assist System

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(LIDAR) mounted behind the windscreen (and so out of harm’s way). It constantlymonitors the road ahead. once an object is within 6 metres, the system calculateswhether the driver is reacting to avoid it. if not, the system will autonomouslyapply up to 50% of the braking power, enough to completely avoid contact at10mph and mitigate the effects of a 20mph crash by 50%. The potential for thereduction of whiplash injuries and damage repair costs is considerable.

4. Secondary Safety Systems

Technology that helps the human occupant survive the forces of aninevitable crash

These system focus purely on the need to protect the occupant in a crash:a. Airbagsb. Seatbelt pre-tensionersc. Anti Whiplash Seatsd. Stronger Occupant Compartmentse. Automatic Collision Notification Systems

Airbags

Driver's airbag

The driver's airbag is integrated in the impact absorber on the steering wheel. Anacceleration detected in the sensor isintegrated and evaluated. The driver'sairbag is fired once the appropriatetriggering thresholds have been exceeded.The actuator receives a firing voltage fromthe airbag control unit or from the relevantsatellite. This releases stored pressure ofthe inert gas from the cartridge whichescapes through the airbag, inflating it.When the airbag inflates, the cover (impactabsorber of driver's airbag, cover ofpassenger airbag, trim of side/head airbags)splits open at the programmed rupturepoint.

The talc from the airbag that is deposited in the passenger compartment is nonhazardous.

Professional rescuers should always consider the use of airbag restaint systems andensure that crews working in the vacinity of airbags adhere to the nationalguidance of 5 - 10 - 15 - 20 rule. This is 5 inches from the side airbag, 10 inchesfrom the drivers airbag, 15 inches from the curtain airbag and 20 inches from thepassenger airbag.

Passenger airbag

The passenger airbag is located in the instrument panel above the glovecompartment on the passenger side. A seat-occupancy detector has beenintegrated for years in order to prevent unnecessary triggering of the passengerairbag in the event of a crash (passenger seat is not occupied).

The front passenger seat is identified as being occupied from a weight of 12 kg bythe sensors in the front passenger seat and through evaluation of the data in theairbag control unit or in the satellite and the system is thereby activated.

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Side airbag

The side airbags are located behind the side trims in the doors and in thebackrests of the driver's and front passenger seats. In the event of a side impact,the transversal acceleration that occurs is measured by appropriate sensors. If thetriggering threshold is exceeded, the airbag control unit or the relevant satellitesfire the side airbags and, if fitted, also the head airbag.

Head Airbag

The ITS (Inflatable Tubular Structure) and AITS (Advanced Inflatable TubularStructure) head airbags are installed along the A-pillar and the roof frame on thedriver's and passenger sides and are fired with the corresponding side airbags.With an additional head airbag at the rear, the airbag is installed along the A-pillar,the roof frame and the C-pillar.

Unlike the other airbags, the ITS head airbag is a tubular system which is securedto the body with belt straps.

The AITS head airbag is a head protection system like the ITS with the advantageof the area protection afforded by a curtain.

When the generator is fired, this increases the diameter of the head airbag,thereby reducing its overall length. With this procedure, the head airbag stretchesbetween the lower end of the A-pillar and the rear attachment to the roof frame.

Unlike front and side airbags, which collapse relatively quickly after inflating, thehead airbag retains the gas volume and thus also offers protection in the event ofthe car rolling over or secondary accidents.

The head airbag can be cut off at the belt straps or cut through safely.

Rear Curtain Airbag

in 2008 the Toyota IQlaunched featuring the firstever rear curtain airbag toprotect the rear occupantsheads in the event of a rearimpact.

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Airbag Disconnection Times - a general guide

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Seatbelt Pre-tensioners

The purpose of seatbelt is to ensure that the occupant of a seat is held in thecorrect position so that in the event of a collision, the risk of persons ‘submarining’is minimised and inertial energies are spread throughout the whole SRS system ina controlled manner i.e. seatbelt restraints, airbag deployments etc. In order tomaintain the seat occupant in the safest position on the seat, seatbelts make useof pre-tensioners, and in recent vehicles employ electronic sensors to measure thespeed and pressures applied upon the seatbelt in the event of an impact. Thisallows a control module on the vehicle to deploy the other safety systems at theappropriate time for the position of the seat occupant, and for the occupant’s bodyto be restrained with a measured force across the seat belt. If the body isrestrained by the belt with excessive force, then the body and its internal organscould suffer an injury. Likewise if the belt force limiter is set too low, the bodycould be thrown forward too quickly against the airbag or surrounding vehiclestructures.

Three types of system are used in the vehicles to reduce belt slack:

Mechanical seatbelt tensioners

The seatbelt tensioners are unlocked mechanically and tighten the seat belts.

Pyrotechnical seatbelt tensioners

The seatbelt tensioners are fired by the airbag control unit or the seat satellites, apyrotechnical unit tightens the seat belt.

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Pyrotechnical anchor-fittingtensioners

The anchor-fitting tensionersare fired by the seat satellites,a pyrotechnical unit tightensthe seat belt.

Anti Whiplash Seats

There is currently considerable research being undertaken by Thatcham ResearchCentre into the effects of seat design and their influences on whiplash injuries.

In an effort to reduce the likelihood of C Spine injuries occuring there are anumber of clever head restraint designs that become active if a rear-end collision isanticipated. Such restraints are now standard in many Mercedes models e.g. C-Class, CLK E-Class, CLS and S-Class.

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Pyrotechnical seatbelt tensioner Pyrotechnical anchor-fitting tensioner

1 Seatbelt tensioner not triggered2 Seatbelt tensioner triggered

Unlike existing active restraints that move forward in reaction to a collision, thesystems such as the Neck Pro system, monitors the vehicle sensors and predictswhen a crash is about to happen. It then releases pre-tensioned springs inside theheadrest, causing the headrest to move forward by 40mm and upwards by 30mmproviding better support for front seated occupants.

Rescuers are likely in the future to come across vehicles with such active headrestarrangements and should consider the risks involved from headrests which havenot yet actuated. Historically where the headrest is used as part of a point ofstability whilst immobilising the C spine with the rescuers hands, such headrestsmay prove an obstacle to utilising existing techniques.

Stronger Occupant Compartments

There are a number of factors that contribute to the continuing development ofvehicle body designs, as are shown in the body development picture above.

Such demands on vehicle manufacturers dictate the materials that need to beconsidered when building a vehicle which has led to a growth in the use ofaluminium and boronated steel materials. Such material usage has greatlyenhanced the strength of occupant compartments but with it come complicationsfor the professional rescuer.

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For further information on the complexities of boronated vehicle construction,reference should be made to the UKRO New Vehicle Technologies Package whichcan be located within the Education section of the UKRO website www.ukro.org.

Advanced Automatic Collision Notification Systems

The advanced automatic collision notification system monitors a vehicles sensorsfor information which may prove useful in the event of a crash. Information fromseat sensors for the number of passengers, airbag deployments, seat beltpretensioner deployments, vehicle orientation, number of rolls, speed of impact,delta velocity, GPS etc are collated and then sent to a communications centre toalert them that the vehicle has been involved in a crash.

One of the first manufacturers to introduce the automatic collision notificationsystem to their vehicles is BMW. Their enhanced ACN sends additional informationfrom the vehicles control units automatically to the BMW assist response centreoperated by ATX Communications. There the data is evaluated and can be passedonto emergency services who would be on route.

As such systems become more commonplace, this will provide the respondingIncident Commander greater time for consideration of the priorities they will befaced with when they arrive on scene. This system will be featured on most 2009and later BMW models, and is featured on models from manufacturers such asFord and Lexus. This represents the next step forward in the rapid and appropriatedeployment of emergency response following a vehicle accident.

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