Advanced Vehicle Systems
The following sections provide key statistics for a number of the collision protection technologies of interest. These statistics give an indication of the effectiveness of each technology. It should be noted that other pieces of research are available which do not appear in this synthesis, therefore the figures presented here are not definitive.
- It is also worth noting that the UK car fleet takes around 12–15 years to turn over, and this can be noticeably longer for heavy vehicles. So it will take several years for measures being implemented now to be sufficiently widespread in the marketplace to noticeably affect casualty numbers.
Adaptive Cruise Control (ACC)
- A research study looked at the effectiveness of ACC and how it reduces the number of crashes on highly congested highways. The results were simulation-based and found that with current market penetration, ACC does little to prevent collisions, and in some cases will create more accidents.
- It was found that the ACC worked best when it had a more responsive operation (i.e. the data was sensed at higher frequency) and when the maximum deceleration rate was greater. It was found that a high reduction in collision risk was only achieved when ACC market penetration was increased to 30%.
(Li et al., 2017)
Advanced Adaptive Front Light System (AAFLS)
- During a Traffic Accident Causation in Europe (TRACE) study, AAFLS had an estimated effectiveness for serious injuries saved of 0.6 per cent.
(Atalar et al, 2012)
Anti-lock Braking Systems
- A meta-analysis of research studies which combined and contrasted results shows that ABS give a relatively small, but statistically significant reduction in the number of RTIs, when all levels of severity and types of RTIs are taken together. The analysis also showed that there were statistically significant increases in rollover, single-vehicle RTIs and RTIs with fixed objects when ABS is fitted. There were statistically significant decreases in RTIs with pedestrians/ cyclists/ animals and RTIs involving turning vehicles. ABS brakes do not appear to have any effect on rear-end RTIs.
Autonomous Emergency Braking Systems
- Substantial difficulties have been encountered in trying to define the benefits of an AEBS in terms of casualty reduction. These are related to fundamental limitations in terms of the detail available in RTI databases and the reconstruction methods used to determine RTI causation.
(Grover et al, 2008)
However, in Germany a figure has been reached to indicate the benefits that AEBS can afford:
- AEBSs are expected to save a total of 9,000 severe and 53,000 slight injuries, corresponding to 10 per cent and 14 per cent of total severe and slight injuries in Germany respectively.
(Atalar et al, 2012)
- When comparing vehicles of the same make and model, one group with AEB and one group without, it has been seen that there is a 43% reduction in rear-end striking crashes and a 45% reduction in rear-end crash involvements with injuries. When the AEB was coupled with FCW, the reduction rates are seen to increase to 50% and 56% respectively.
- If all vehicles in the US market were equipped with AEB and FCW, then almost 1 million rear end crashes, and 400,000 associated injuries could have been prevented in 2014
(Cicchino for IIHS, 2017)
- A study found a 38% overall reduction in rear-end crashes for vehicles fitted with AEB, when compared to a comparison sample of similar vehicles.
- There was no statistical evidence to suggest a difference in effect between urban (<60km/h) and rural (>60km/h) speed zones.
(Fildes et al., 2015)
Brake Assist Systems
- An evaluation of German RTI data (from 2002) and driver simulator studies have led to the estimation by ECORYS (as part of an EU project) that BAS could avoid 4 per cent of fatal RTIs in Europe.In 2005, 5 per cent of vehicles in the EU were equipped with BAS. Although this is expected to rise to 20 per cent by 2025.
(Broughton et al, 2009)
- BAS is now compulsory for all new vehicles in the EU, established by Regulation (EC) 78/2009 to enhance protection for pedestrians.
- A study into the effect of BAS on pedestrian safety has shown that although the implementation of BAS was unlikely to avoid a collision with pedestrians, in most cases the collision would result in less severe pedestrian injuries.
- In a small number of cases, the lower collision speed would actually increase head injury severity, this due to the anthropometrics of the pedestrian and head landing position of the pedestrian (e.g. A-pillar).
(Badea-Romero et al, 2013)
- It is likely that a significant number of new cars now employ a collaborative system which uses both BAS and AEB. BAS has been mandatory on all new vehicles in the EU since 2014, and with Euro NCAP testing for AEB systems since 2016, less expensive vehicles are now adopting AEB as standard (such as the 2017 Seat Ibiza).(Euro NCAP, 2015)
(EU Commission, 2009)
Daylight Running Lights
- There is evidence to suggest that operating DRL would result in a net casualty reduction in the region of 5 per cent. This was calculated using a meta-analysis of a large body of research related to DRL. These research studies used one of three estimators of effect; the accident rate ratio (ARR), the odds ratio (OR) or the ratio of odds ratio (ROR).
(Broughton et al, 2009)
- Two meta-analyses of the effects of daytime running lights on cars show that the measure contributes substantially to reducing road RTIs. The first study, which examined daytime RTIs involving more than one party, found a reduction in the number of RTIs of around 13 per cent with the use of daytime lights, and a reduction of between 8 per cent and 15 per cent as a result of introducing mandatory laws on daytime use.
- The number of pedestrians and cyclists hit by cars was reduced by 15 per cent and 10 per cent, respectively.
- Another study found a reduction of slightly over 12 per cent in daytime RTIs involving more than one party, a 20 per cent decrease in injured victims and a 25 per cent reduction in deaths in such RTIs.
- A study of data over four years from nine American states concluded that, on average, cars fitted with automatic daytime running lights were involved in 3.2 per cent fewer multiple RTIs than vehicles without.
- A cost–benefit analysis of providing automatic light switches on cars for daytime running lamps using standard low-beam headlights found that the benefits outweighed the costs by a factor of 4.4.
- Motorized two-wheeler users have expressed concerns that daytime running lights on cars could reduce the visibility of motorcyclists. While there is no empirical evidence to indicate this is the case, researchers have suggested that if such an effect did exist, it would be offset by the benefit to motorcyclists of increased car visibility.
(Peden et al, 2004)
Electronic Stability Control
Despite widespread use of ESC, quantifying its effectiveness in terms of RTI rates has proved challenging.
- Often the basic approach used to assess the effectiveness of ESC has been to compare the RTI-involvement rates of cars with and without ESC.
- Assessing the actual effectiveness of such primary safety features in reducing the number of casualties in RTIs can be very difficult. Probably the main reason for this difficulty is that if a primary safety feature is fully effective then there would be no RTIs of the relevant type and therefore, no data for comparison. However, alternative methods use existing accident data to attempt to predict the effectiveness of technologies before they reach the market.
(Broughton et al, 2010)
In 2007 Frampton and Thomas conducted an analysis of RTI data which used a case-control methodology.
- An analysis of RTIs involving 10,475 vehicles with ESC and 41,656 vehicles without ESC in GB showed that:
- Serious RTIs were 11 per cent lower compared to non ESC cars; and,
- Fatalities were 25 per cent lower compared to non ESC cars.
- The potential savings in RTI costs for a 100 per cent take up of ESC amounts to some £959 million by preventing some 7,800 RTIs.
- ESC appears to offer additional benefit in adverse road conditions.
- ESC was particularly effective for skidding and overturning RTIs - typically where a driver enters a bend too quickly and attempts to steer.
- Compared to non-ESC cars, 27 per cent fewer ESC vehicles were involved in all single vehicle RTIs compared to 7 per cent for multi and single vehicle RTIs taken together. Unfortunately case numbers did not allow a reliable assessment of ESC contribution to the reduction in serious single vehicle RTIs.
- Overall, ESC has shown worthwhile reductions in both RTI frequency and cost across a wide variety of RTI situations.
(Frampton and Thomas, 2007)
In a study conducted by Broughton et al (2010), ESC was found to reduce the overall RTI-involvement rate by about one fifth, although the effect was less for serious RTIs and not significant for fatal RTIs.
The effects varied widely among car models, and analyses failed to yield satisfactory results for several models because of the low number of cars of these models that had ESC fitted as standard.
(Broughton et al, 2010)
During this study cars with ESC and cars without ESC were compared.
- Studies implicitly assume that cars with and without ESC are driven in similar circumstances, for similar mileages and with similar drivers, so that any differences in their RTI-involvement can be interpreted as the effects of ESC. However, analyses of STATS19 RTI data demonstrate that the driver profiles of the two groups of car may well differ in terms of age and sex.
(Broughton et al, 2010)
In a study conducted by Hoye (2011), several studies regarding the effectiveness of ESC were compared and analysed. The study found:
- ESC prevents about 40% of all crashes involving loss of control.
- All fatal crashes are reduced by around 40%; less severe crashes are unchanged when all types of crashes are regarded together.
- Fatal crashes in which rollover is the first harmful event are reduced by 70%, rollover crashes of all severities are reduced by 50%.
- Run-off-road crashes are reduced by about 40%, and single vehicle crashes are reduced by about 25%.
- Results are likely to be overestimated, especially with non-fatal crashes.
Forward Collision Warning (FCW)
- When comparing similar vehicles in collisions between 2010 and 2014, it was found that the vehicles which were equipped with FCW had a reduced involvement in rear end collisions by 27%.
- FCW also related to a 20% reduction in rear end collisions involving injures in instances where a collision couldn’t be avoided.
- In 2014, nearly 1 million rear end crashes, and 400,000 injuries could have been avoided if all vehicles had a combination of FCW and AEB.
(Cicchino for IIHS, 2017)
High Beam Assist
- An SAE paper researched the implications of high beam assist and what effects it could have on roads in the USA.
- It was found that the application of high beam assist on vehicles could reduce the number of night time vehicle crashes by 6.7%. This is through providing better visibility for the driver operating the vehicle, and producing less glare for on-coming vehicles.
- A study looked at the effect of ADAS for older drivers when crossing junctions. The main parameter that the study focussed on was the effectiveness of the junction assist.
- The junction assist in this case told the drivers how much time they had between vehicles, as well as telling them whether or not it was safe to cross the junction.
- The results showed that the system affected the driving and decisions made by the drivers. It found that they crossed the junction in a shorter time and at higher speeds, and were often crossing the junction with a critical time until collision time. This is a potential drawback of the system.
(Dotzauer et al, 2013)
Lane Keeping Assistant (LKA)
- During a TRACE study the estimated effectiveness for serious injuries saved was 5.7 per cent when LKA is used; no figures were given for the number of fatalities reduced.
- The system is most effective on rural roads and motorways where vehicles often change lanes at high speed. A LKA is far less effective on urban roads because other vehicles are in close proximity more often.
(Atalar et al, 2012)
- The technical and operational feasibility of such systems has still to be demonstrated. Most existing systems are warning only systems.
- A 2017 study looked at the influence on driving behaviour from a warning from a LDW system. It was found that a more effective recovery manoeuvre was seen when the warning came when there was a warning of partial lane departure, rather than full lane departure warnings.
- It was seen that drivers spent more time out of their driving lane when they received no warning from the system.
- Subjectively, LDW did not reduce mental workload on the driver, and partial lane departure warning was judged more trustworthy than full lane departure.
(Navarro et al, 2017)
- Another study found that LDW/LKA systems were estimated to reduce head-on and single vehicle collisions on Swedish roads by 53%. This reduction corresponded to a reduction of 30% for all head-on and single vehicle collisions.
(Sternlund et al, 2017)
- An Insurance Institute for Highway Safety (IIHS) report found that two-thirds of Honda drivers in the USA had LDW activated, as they found it ‘annoying’ when it would alert them.
Mandatory Intelligent Speed Adaptation (ISA)
- Research indicates that the more the system intervenes the more significant are the benefits. The use of a mandatory ISA system, when combined with a dynamic speed limit regime, has the estimated potential to reduce overall injury RTIs by up to 36 per cent, fatal and serious RTIs by 48 per cent and fatal RTIs by 59 per cent.
- The safety effects that current ISA technology can deliver are already impressive. Research has shown that non-overridable intervening ISA could deliver a 37 per cent reduction in fatal RTIs in the UK.
- In other EU countries, up to 50 per cent of traffic deaths could be avoided if all cars were equipped with supportive ISA.
(Goodwin et al, 2006)
Overtaking is a complicated process where the driver must concentrate on many aspects. Drivers will need to control their interaction with the vehicle they wish to overtake and estimate the time needed to overtake safely. Simulator studies can help to identify whether overtaking behaviour changes when a mandatory ISA system is active.
- The results of a recent simulator study indicated that drivers are less inclined to initiate an overtaking manoeuvre when the mandatory ISA is active and this was particularly so when the overtaking opportunity was short.
- In addition to this, when ISA was activated drivers were more likely to have to abandon an overtaking, presumably due to running out of road.
- The quality of the overtaking manoeuvre was also affected when mandatory ISA was active, with drivers pulling out and cutting back in more sharply.
- In contrast, when driving with a voluntary ISA, overtaking behaviour remained mostly unchanged: drivers disengaged the function in approximately 70 per cent of overtaking scenarios.
- The results of this study suggest that mandatory ISA could affect the safety of overtaking manoeuvres unless coupled with an adaptation period or other driver support functions that support safe overtaking.
(Jamson et al, 2012)
Rear Cross Traffic alert
- The National Highway Traffic Safety Administration (NHTSA) released a report about Not-in-Traffic injuries and fatalities. The report details collisions on private roads, car parks and drive ways.
- In 2011, there were 189 recorded fatalities and around 12,000 recorded injuries from reversing vehicles in the USA.
Only USA data is accessible. In the UK, crash statistics are built up from the STATS 19 database, which doesn’t include car parks which are classified as private land.
Two Wheeled Motor Vehicle braking systems
- Simulations were run to establish the effects that MAEB could have had on real world, motorcycle accidents. The research found that there were some positive effects from the MAEB application. It was seen that there was 10% reduction in impact speed when MAEB was applied, in certain crash situations. The results shed light on the feasibility of MAEB in different speed ranges.
(Savino et al, 2014)
Vulnerable Road Users protection
- Simulations were run to test the extent to which an AEB system is capable of identifying a cyclist or pedestrian, and the success with which it can avoid a collision.
- Scenarios with a pedestrian emerging at small time to collision from behind an obstacle prove the most difficult to mitigate with current technology, and will very likely never be avoidable for all vehicle speeds due to physical limitations.
- Scenarios with an unobstructed person walking will very likely be treatable for a wide speed range of next generation AEB systems.
(Seiniger et al, 2013)
Gaps in the research
It is well known that primary safety systems are not currently widespread. This means that there is a lack of real life data related to the effectiveness of such technologies. There also seems to be no standard way of evaluating effectiveness.
In-vehicle data recorders (“black boxes”) offer a good potential source of RTI data for understanding the performance of active technologies both in RTIs and when RTIs are successfully avoided.
In addition to RTI data it is also desirable to understand system exposure on the road in terms of, for example, number of systems in use, distance driven and type of road. This data is needed before accurate accident risks with and without the fitment of a technology can be calculated. Further work is needed to establish such exposure data and in a form that is compatible with the relevant RTI data.
Most vehicles are fitted with multiple systems, for example ESC, AEBs and airbags. A significant challenge is to isolate the effectiveness of individual systems when working alongside other systems in the same RTI in the same vehicle. The majority, if not all, of the studies presented in this synthesis do not address effectiveness in multiple systems. Similar systems can be significantly different across a range of manufacturers. For example, an ESC system in one vehicle may have a different control algorithm from an ESC system fitted to another. This represents a further challenge for the analysis of effectiveness of systems because it is not easy for the investigator to identify or understand different algorithms. It is important to be able to study performance at that level of detail in order to identify effectiveness and needs for future development.
The monitoring of driver behaviour in response to new technologies is also important and more studies which determine whether technology has a positive or negative impact on behaviour are required.
- Date Added: 03 Apr 2012, 08:19 AM
- Last Update: 21 Aug 2017, 12:43 PM