| 1. |
- Dean, Morgan E., et al.
(författare)
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Assessing the applicability of impact speed injury risk curves based on US data to defining safe speeds in the US and Sweden
- 2023
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Ingår i: Accident Analysis and Prevention. - 0001-4575. ; 190
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Tidskriftsartikel (refereegranskat)abstract
- Vision Zero is an approach to road safety that aims to eliminate all traffic-induced fatalities and lifelong injuries. To reach this goal, a multi-faceted safe system approach must be implemented to anticipate and minimize the risk associated with human mistakes. One aspect of a safe system is choosing speed limits that keep occupants within human biomechanical limits in a crash scenario. The objective of this study was to relate impact speed and maximum delta-v to risk of passenger vehicle (passenger cars and light trucks and vans) occupants sustaining a moderate to fatal injury (MAIS2+F) in three crash modes: head-on vehicle-vehicle, frontal vehicle–barrier, and front-to-side vehicle-vehicle crashes. Data was extracted from the Crash Investigation Sampling System, and logistic regression was used to construct the injury prediction models. Impact speed was a statistically significant predictor in head-on crashes, but was not a statistically significant predictor in vehicle-barrier or front–to–side crashes. Maximum delta-v was a statistically significant predictor in all three crash modes. A head-on impact speed of 62 km/h yielded 50% (±27%) risk of moderate to fatal injury for occupants at least 65 years old. A head-on impact speed of 82 km/h yielded 50% (±31%) risk of moderate to fatal injury for occupants younger than 65 years. Compared to the impact speeds, the maximum delta-v values yielding the same level of risk were lower within the head-on crash population. A head-on delta-v of 40 km/h yielded 50% (±21%) risk of moderate to fatal injury for occupants at least 65 years old. A head-on delta-v of 65 km/h yielded 50% (±33%) risk of moderate to fatal injury for occupants younger than 65 years. A maximum delta–v value of approximately 30 km/h yielded 50% (±42%) risk of MAIS2+F injury for passenger car occupants in vehicle-vehicle front-to-side crashes. A maximum delta–v value of approximately 44 km/h yielded 50% (±24%) risk of MAIS2+F injury for light truck and van occupants, respectively, in vehicle-vehicle front-to-side crashes.
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| 2. |
- Lübbe, Nils, 1982, et al.
(författare)
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Injury risk curves to guide safe speed limits on Swedish roads using German crash data supplemented with estimated non-injury crashes
- 2024
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Ingår i: Accident Analysis and Prevention. - 0001-4575. ; 202
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Tidskriftsartikel (refereegranskat)abstract
- Vision Zero postulates that no one should be killed or seriously injured in road traffic; therefore, it is necessary to define evidence-based speed limits to mitigate impact severity. The overall aims to guide the definition of safe speeds limits by establishing relations between impact speed and the risk of at-least-moderate (MAIS2+) and at-least-severe (MAIS3+) injuries for car occupants in frontal and side crashes in Sweden. As Swedish in-depth data are unavailable, the first objective was to assess the applicability of German In-depth Accident Study (GIDAS) data to Sweden. The second was to create unconditional injury risk curves (risk of injury given involvement in any crash), rather than risk curves conditional on the GIDAS sampling criterion of suspected-injury crashes. Thirdly, we compared the unconditional and conditional risk curves to quantify the practical implications of this methodological choice. Finally, we provide an example to demonstrate how injury risk curves facilitate the definition of safe, evidence-based speed limits in Sweden. Characteristics important for the injury outcome were similar between GIDAS and Swedish data; therefore, the injury risk curves using German GIDAS data are applicable to Sweden. The regression models yielded the following results for unconditional injury risk curves: 10 % MAIS2+ at 25 km/h impact speed for frontal head-on crashes, 20 km/h for frontal car-to-object crashes, 55 km/h in far-side crashes, and 45 km/h in near-side crashes. A 10 % MAIS3+ risk was reached between 70 and 75 km/h for all crash types. Conditional injury risk curves gave substantially different results; the 10 % MAIS3+ risk in near-side crashes was 140 km/h, twice the unconditional value. For example, if a 10 % MAIS3+ risk was acceptable, treating remaining uncertainty conservatively, assuming compliance with speed limits and that Automated Emergency Braking takes 20 km/h of the travel speed before impact in longitudinal traffic, the safe speed limit for car occupants on most Swedish roads would be 80 km/h and 60 km/h in intersections.
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| 3. |
- Rizzi, Matteo, 1979, et al.
(författare)
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Motorcycle crashes into road barriers: The role of stability and different types of barriers for injury outcome
- 2012
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Ingår i: 2012 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, Dublin:12 September through14 September 2012. ; , s. 328-341
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Konferensbidrag (refereegranskat)abstract
- This research focused on motorcycle crashes into road barriers and addressed two research questions: the first to assess if injury risk for motorcyclists is affected by collisions with different types of barriers, and the second, to examine if injury outcome in these crashes can be affected by being in an upright position during the collision. Police-reported motorcycle crashes into road barriers in Sweden between 2003 and 2010 were analyzed across different barrier types, using the Fatal-Serious-Injury Ratio (FSI). In addition, 55 in-depth interviews with Swedish motorcyclists who had crashed into road barriers were included to measure threat-to-life and medical disability. The analysis of police records showed no statistically significant difference between the FSI-ratios for wire rope barriers, Kohlswa-beam and W-beam barriers, although these FSI-ratios were generally very high. The small number of in-depth case findings, however, showed that injury severity was lower in crashes in which the motorcyclists were in an upright position during the collision. The proportion of subjects with ISS 16+ was 24% lower in those crashes compared to those who slid into the barrier. In addition, AIS 2+ and AIS 3+ injuries were 22% and 12% lower, respectively. The mean Risk for Permanent Medical Impairment 10% (RPMI) was 51% lower, and leg injuries were more common although these results were not statistically significant. While the implementation of Anti-lock Brakes on motorcycles may improve stability during critical situations, further development of integrated leg protectors might still be needed.
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| 4. |
- Sternlund, Simon, 1983
(författare)
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The effectiveness of centerline rumble strips (CLRS) on two-lane carriageways in Sweden on injury accident risk for cars equipped with electronic stability control (ESC) and cars without ESC
- 2019
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 20:8, s. 880-885
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Electronic Stability Control (ESC) and Lane Departure Warning (LDW) are in-vehicle safety systems that complement each other. While the implementation of on-board lane support systems in traffic is still limited and the majority of the traffic volume is made up by ESC-equipped cars, the effectiveness of centerline rumble strips (CLRS) for ESC-equipped cars need to be quantified. The aim of the present study is to estimate the effectiveness of CLRS on two-lane carriageways in Sweden, on injury accident risk for cars equipped with ESC and cars without ESC. Methods: Police reported injury crashes during 2011-2016 were extracted from the Swedish Traffic Accident Data Acquisition (STRADA) database and merged with the National Road Database (NVDB) containing information regarding road design and road use parameters. The analysis includes crashes on two-lane carriageways in Sweden with a width of at least seven meters in dry and wet road conditions, that is, road surface not covered by ice or snow. The crashes involved a total of 7,490 cars with injured drivers, where 39% of the cars were equipped with ESC. The effectiveness estimates were calculated for injured drivers in ESC-equipped cars in crashes involving drift out of lane to the left, and posted speed limits of 80 and 90 km/h. The analysis was carried out by applying the induced exposure approach in which rates of cars involved in crashes sensitive and non-sensitive to CLRS were compared at sites with and without CLRS. In order to substantiate the evidence for causality, case and control rates of car model year and Seat Belt Reminder (SBR) fitment, driver age, driver gender, traffic volume, road width, speed limit and road surface condition were compared. Results: For ESC-equipped cars, the analysis showed a reduction in CLRS-sensitive crashes by 40% (19-56%, confidence interval [CI] 95%) where CLRS had been implemented, and a reduction by 29% (11-44%, CI 95%) for cars without ESC-equipment. Conclusions: Contemporary effectiveness estimates may have important implications for the short and medium-term national road safety management. CLRS remains an important countermeasure to consider for reducing the number of real-world injury crashes. From a systematic safety perspective, it is important to accentuate that CLRS and ESC essentially address different crash scenarios. Still, both CLRS and ESC have the potential to avoid crashes involving unintentional lane drifting resulting in loss of control. When the CLRS alerts a driver of unintentional lane drifting, the ESC can be essential in supporting the driver to safely veer back into the lane without loss of control. However, further analysis on the combined safety benefit of ESC and CLRS is required.
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| 5. |
- Sternlund, Simon, 1983, et al.
(författare)
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The effectiveness of lane departure warning systems—A reduction in real-world passenger car injury crashes
- 2017
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 18:2, s. 225-229
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of this study was to estimate the safety benefits of in vehicle lane departure warning (LDW) and lane keeping aid (LKA) systems in reducing relevant real-world passenger car injury crashes. Methods: The study used an induced exposure method, where LDW/LKA-sensitive and nonsensitive crashes were compared for Volvo passenger cars equipped with and without LDW/LKA systems. These crashes were matched by car make, model, model year, and technical equipment; that is, low-speed autonomous emergency braking (AEB) called City Safety (CS). The data were extracted from the Swedish Traffic Accident Data Acquisition database (STRADA) and consisted of 1,853 driver injury crashes that involved 146 LDW-equipped cars, 11 LKA-equipped cars, and 1,696 cars without LDW/LKA systems. Results: The analysis showed a positive effect of the LDW/LKA systems in reducing lane departure crashes. The LDW/LKA systems were estimated to reduce head-on and single-vehicle injury crashes on Swedish roads with speed limits between 70 and 120 km/h and with dry or wet road surfaces (i.e., not covered by ice or snow) by 53% with a lower limit of 11% (95% confidence interval [CI]). This reduction corresponded to a reduction of 30% with a lower limit of 6% (95% CI) for all head-on and single-vehicle driver injury crashes (including all speed limits and all road surface conditions). Conclusions: LDW/LKA systems were estimated to lower the driver injury risk in crash types that the systems are designed to prevent; that is, head-on and single-vehicle crashes. Though these are important findings, they were based on a small data set. Therefore, further research is desirable to evaluate the effectiveness of LDW/LKA systems under real-world conditions and to differentiate the effectiveness between technical solutions (i.e., LDW and LKA) proposed by different manufacturers.
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| 6. |
- Sternlund, Simon, 1983
(författare)
-
The Safety Potential and Effectiveness of Lane Departure Warning Systems in Passenger Cars
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the road transport system, crashes due to lane departure account for a large proportion of the most severe crashes that passenger car occupants are exposed to. While Electronic Stability Control (ESC) effectively prevents lane departure due to loss of control, lane departure due to unintentional drifting has not been addressed to the same extent. This thesis is based on two papers aimed at increasing the knowledge of the safety potential and effectiveness of lane keeping support. Paper 1 aims to identify and characterise lane departure crashes and identify the safety potential of lateral support systems such as Lane Departure Warning (LDW) by using real-world in-depth data of fatal crashes in Sweden. Single car, head-on and overtaking crashes involving lane departure without prior loss of control were categorised into intentional lane change, evasive manoeuvre or unintentional drift out of lane. The latter category accounted for half (51/100) of the single vehicle and head-on crashes and LDW systems have the potential to prevent a majority (33 to 38) of these crashes. Paper 2 aims to estimate the effectiveness of LDW in real-world passenger car injury crashes, extracted from the Swedish Traffic Accident Data Acquisition (STRADA). The induced exposure method and information of each individual car’s equipment were used. LDW halved the risk of being in a head-on or single passenger car driver injury crash where the posted speed limits were 70 km/h and above and where the road surface was not covered by ice or snow. This thesis shows results in line with other research considering the safety potential and effectiveness of lane keeping support. While related research used risk measure exposure such as insured vehicle days or vehicle miles travelled to estimate effectiveness of LDW, Paper 2 used induced exposure where the exposure is made up by non-sensitive crashes. The induced exposure method has advantages of incorporating possible changes in driver behaviour and usage rates in real-world traffic. Despite applying two very different methods of analysis, the two papers synthesised in this thesis show results that corroborate each other. In conclusion, LDW is part of a system where detectable lane markings provided by road authorities and vehicles technology have to work together and shows significant traffic safety benefits under certain conditions. As both components are dependent on each other to create safety, this makes safety the responsibility of both road authorities and the car industry. Lane keeping support systems, such as LDW, is one of the most important safety features in the foreseeable future, where the share of unintentional drifting crashes could be expected to increase due to ESC addressing loss of control. Therefore, different organisations and road safety stakeholders should promote the fitment of LDW systems in new cars and speed up the implementation in traffic.
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| 7. |
- Sternlund, Simon, 1983
(författare)
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The safety potential of enhanced lateral vehicle positioning
- 2021
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 22:2, s. 139-146
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of this study is to estimate the potential safety benefits of Emergency Lane Keeping (ELK) and Autonomous Emergency Steering (AES) systems with precise and reliable lateral positioning. Methods: The material comprised in-depth studies of fatal road crashes in Sweden in 2017. Crashes resulting in passenger car occupant fatality (n = 114) were included; single vehicle (n = 60) and head-on (n = 31), intersection (n = 9), rear-end (n = 5), overtaking (n = 5), animal (n = 1), other (n = 1, U-turn), and train (n = 2). Additionally, fatal collisions between motor vehicles and vulnerable road users (VRUs) were included; pedestrians (n = 36), cyclists/moped users (n = 15), and motorcyclists (n = 17). A case-by-case analysis was conducted to identify crashes potentially prevented by ELK and AES with precise (within 0.1 m accuracy) and reliable lateral positioning. The identified crashes potentially avoided by ELK systems involved unintentional drift-out-of-lane on roads with posted speed limits of ≥70 km/h (43 mph). For comparison, the same material was used to identify the potential safety benefits of the more traditional lane departure warning (LDW) and Lane Keeping Assist (LKA) systems without enhanced lateral positioning. Crashes potentially avoided by LDW/LKA occurred on roads with visible lane markings and without rumble strips on the departure side while ELK with enhanced lateral positioning is not reliant on lane markings. Collisions potentially avoided by AES occurred on roads with sufficient escape zones and road friction. Results: The study shows that ELK systems with enhanced lateral positioning could potentially avoid 33 − 45 (36 − 49%) out of 91 head-on and single car crashes resulting in passenger car occupant fatality, which corresponds to a further 18% (5/28) compared to traditional lane support (LDW/LKA) without enhanced lateral positioning. The improved lane keeping addresses crashes involving absent or nonvisible lane markings that are covered by snow. Furthermore, the study shows that the evasive steering features of AES systems with enhanced lateral positioning could potentially prevent 28 (54%) out of 52 collisions resulting in passenger car occupant fatalities (i.e., head-on, intersection, rear-end, overtaking, and animal collision). Additionally, AES with enhanced lateral positioning could potentially prevent 16 (31%) out of 51 collisions between motor vehicles and vulnerable road users resulting in fatally injured pedestrians, cyclists or moped users. The total potential safety benefits of AES include both lane keeping and evasive steering features including lane escaping. The study identified that the total number of crashes potentially avoided by AES corresponds to 42% out of all crashes resulting in passenger car occupant fatalities (n = 48/114). Conclusions: This is a first attempt to identify and quantify the increase in potential safety benefits, based on the assumption that robust lateral vehicle positioning has been applied to lane keeping as well as lane escaping. In addition to the potentially increased number of prevented crashes compared to traditional lane support, a robust lateral positioning system may have the potential to improve the redundancy in positioning systems. Previous research suggests several techniques to improve lateral vehicle positioning. However, further research is required, including testing for implementation of adequately improved lateral vehicle awareness to establish which techniques are appropriate.
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| 8. |
- Sternlund, Simon, 1983
(författare)
-
The safety potential of lane departure warning systems - A descriptive real-world study of fatal lane departure passenger car crashes in Sweden
- 2017
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 18, s. S18-S23
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Lane departure crashes account for a significant proportion of passenger car occupant fatalities and serious injuries. Utilizing real-world data involving fatal passenger car crashes in Sweden, the characteristics of lane departure crashes were identified and the safety potential of lane departure warning (LDW) systems was quantified.Methods: The material consisted of 104 in-depth studies of fatal passenger car crashes in 2010. The crashes were classified as single-vehicle (n = 48), head-on (n = 52), and overtaking (n = 4) crashes. These crash types were identified as crashes that could have potentially involved lane departure. A case-by-case analysis was carried out and lane departure crashes were identified and characterized using police reports and information collected by crash investigators at the Swedish Transport Administration; for example, inspections and photographs of the crash sites and of the involved vehicles. Lane departure crashes were separated from crashes where loss of control occurred pre-lane departure. Furthermore, loss of control post-lane departures were identified. When studying the pre-stage of lane departure without prior loss of control, crashes were categorized as unintentional drifting, intentional lane change, or evasive maneuver. Using previously published effectiveness information, the potential for LDW systems to prevent crashes was estimated.Results: Of all crashes with passenger car occupant fatalities in Sweden in 2010, 46% (63/138) were found to relate to lane departure without prior loss of control. These crashes accounted for 61% (63/104) of all single-vehicle, head-on, and overtaking crashes. The remaining 41 crashes were due to loss of control pre-lane departure. Unintentional drifting accounted for 81% (51/63) of all lane departure crashes without prior loss of control, which corresponded to 37% (51/138) of all fatal passenger car occupant crashes. LDW systems were found to potentially prevent 33-38 of the 100 fatal head-on and single vehicle crashes. These crashes involved drifting and occurred on roads with visible lane markings, signed posted speed limits 70km/h, and without rumble strips on the corresponding lane departure side. The range of potentially prevented crashes (33-38) is due to the inclusion or exclusion of crashes involving excessive speeding.Conclusions: In this study, approximately half (51/100) of all head-on and single-vehicle crashes were identified as being a consequence of drifting, where LDW systems had the potential to prevent the majority (33-38) of these crashes. The typical lane departure crash without prior loss of control occurred on undivided roads in rural areas with signed posted speed limits 70km/h, where the center and side road markings were visible.
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| 9. |
- Sternlund, Simon, 1983
(författare)
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Traffic Safety Potential and Effectiveness of Lane Keeping Support
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the road transport system, crashes due to lane departure account for a large proportion of the most severe crashes that passenger car occupants are exposed to. While Electronic Stability Control (ESC) effectively prevents lane departure due to loss of control, lane departure due to unintentional drifting has not been addressed to the same extent. This thesis is based on four papers providing knowledge of lane keeping support integrated in vehicles and road infrastructure. More precise, the safety potential and effectiveness of Lane Departure Warning (LDW) was studied as well as the effectiveness of centreline rumble strips (CLRS). Also, the potential safety benefits of Emergency Lane Keeping (ELK) and Autonomous Emergency Steering (AES) with enhanced lateral vehicle positioning were studied. Reviewing real-world in-depth data of 138 fatal crashes in Sweden 2010 and 114 in 2017, the results show that virtually half of the single vehicle and head-on crashes involved unintentional drift-out-of-lane, where LDW, ELK and AES should have had the potential to prevent the majority of these crashes. Estimating the effectiveness of LDW by analysing 1,853 police reported real-world injury crashes during 2007‒2015 extracted from the Swedish Traffic Accident Data Acquisition (STRADA) database and applying the induced exposure method, it was found that LDW halved the risk of being in a head-on or single passenger car injury crash. Posted speed limits were at 70 km/h and above and the road surface had not been covered by ice or snow. Estimating the effectiveness of CLRS by merging STRADA injury crashes during 2011‒2016 involving 7,490 cars with the National Road Database in Sweden (NVDB) and applying the induced exposure method, the results show a reduction in head-on and single car crashes. Crashes involving drift-out-of-lane to the left were reduced by 40% (19‒56%) for ESC-equipped cars, and by 29% (11‒44%) for cars without ESC. It could be confirmed that in-depth data with high detail can provide benefits in evaluating future road safety features. Furthermore, it was found that merging STRADA, NVDB and individual vehicle equipment data has significant methodological benefits in combination with data efficient methods such as the induced exposure approach. LDW provided by the vehicle industry and detectable lane markings provided by road authorities are parts of a system showing significant traffic safety benefits. As both components are dependent on each other, this makes safety the responsibility of both road authorities and the vehicle industry. Not only do LDW and CLRS complement each other, they also complement ESC and are able to avoid critical situations. LDW and CLRS are two of the most important traffic safety features for the foreseeable future, in which the share of unintentional lane drifting crashes is expected to increase. ELK will in the near future be mandatory for new cars, hereby detectable lanes and lateral vehicle position awareness will be even more important. Future research should focus on increasing the synergy between car and infrastructure interventions, holistically and systematically utilising the integrated safety chain.
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| 10. |
- Strandroth, Johan, 1978, et al.
(författare)
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A New Method to Evaluate Future Impact of Vehicle Safety Technology in Sweden
- 2012
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 56, s. 497-509
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Tidskriftsartikel (refereegranskat)abstract
- In the design of a safe road transport system there is a need to better understand the safety challenges lying ahead. One way of doing that is to evaluate safety technology with retrospective analysis of crashes. However, by using retrospective data there is the risk of adapting safety innovations to scenarios irrelevant in the future. Also, challenges arise as safety interventions do not act alone but are rather interacting components in a complex road transport system. The objective of this study was therefore to facilitate the prioritizing of road safety measures by developing and applying a new method to consider possible impact of future vehicle safety technology. The key point was to project the chain of events leading to a crash today into the crashes for a given time in the future. Assumptions on implementation on safety technologies were made and these assumptions were applied on the crashes of today. It was estimated which crashes would be prevented and the residual was analyzed to identify the characteristics of future crashes. The Swedish Transport Administration's in-depth studies of fatal crashes from 2010 involving car passengers (n=156) were used. This study estimated that the number of killed car occupant would be reduced with 53 percent from the year 2010 to 2020. Through this new method, valuable information regarding the characteristic of the future crashes was found. The results of this study showed that it was possible to evaluate future impact of vehicle safety technology if detailed and representative crash data is available.
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