Truck front end designs
On the 12th of December 2017, the European Commission published a study on enhanced truck front end designs.
In 2014 there were over 3,850 reported road fatalities across the EU 28 countries due to collisions involving heavy goods vehicles (HGVs) of >3.5 tonnes, accounting for 15% of all such fatalities (ERSO, 2016). Passenger car occupants were the most common fatality in collisions involving HGVs, accounting for almost half of all reported road fatalities. Pedestrians and pedal cyclists, when considered together, were the next most common fatality in a HGV collision (~25%), whilst just over 10% of fatalities resulting from HGV collision were HGV occupants themselves.
When compared to car occupants, however, it is evident that both pedestrians and pedal cyclists are at greater risk of more severe injuries during collisions with HGVs. Where the injury severity for casualties involved in collisions with HGVs were reported by the European CARE database, pedestrians were found to have the greatest proportion of killed and seriously injured (KSI) casualties (>40%). Pedal cyclists had the next largest proportion of KSIs (~35%), whilst car occupants had the greatest proportion of slight injuries (>70%). This imbalance in the distribution of injury severities among pedestrians and cyclists, in comparison to car occupants, has led to calls to better protect these vulnerable road users (VRUs) during HGV collisions.
Current traditional European HGV designs primarily employ cab-over-engine tractor unit configurations to maximise the commercial loading space within the current dimensions permitted by Council Directive 96/53/EC. The tightly packaged design promoted by this Directive does not encourage adequate space for suitable crumple zones to protect other road users, whilst its cuboid cab design, coupled with a high driver position, increases the difficulty of detecting VRUs, especially on the nearside (passenger side) of the vehicle.
Directive (EU) 2015/719 (which amends 96/53/EC) provides HGV cab length derogations that allow manufacturers to design extended cabs (or enhanced truck front end designs (TFED)), as long as the additional length is not used to increase load carrying capacities. These derogations are only permitted, however, if the new design improves the safety of the HGV for other road users, driver comfort and the aerodynamic efficiency of the HGV. Through this, the Directive aims to encourage improvements in HGV designs, without the economic disbenefits associated with a reduction in commercial load carrying capacity. Importantly, for this project, these aerodynamic improvements must be supported by an improvement in HGV safety, with this focussing in particular on better VRU detection and mitigating the severity of damage or injuries caused to other road users.
The approach proposed by Directive 2015/719 permits cab length derogations based on requirements to implement a specific cluster of regulated safety measures. The particular safety measures proposed for clustering by the European Commission included regulating improvements to the direct vision, indirect vision, VRU impact protection, front underrun protection and VRU airbag performance of enhanced TFEDs, in addition to considering the effects of primary active safety systems. The effect of clustering these solutions and technologies remains unknown, however, with some solutions potentially complimenting each other to result in a combined package that is more cost-effective than the sum of its component parts and others resulting in overlapping benefits where costs could be incurred more than once for the same potential benefit.
The principal aim of this project was to support the technical requirements for Directive (EU) 2015/719 that enhance vulnerable road user (VRU) and passenger car occupant safety through enhanced truck front end designs (TFEDs); in particular focussing on the cab length derogation opportunities provided through the Directive. The scope of the research included prioritising how VRU and car occupant fatalities and casualties can be prevented, or injuries mitigated, by potential regulatory changes to the requirements for the most cost-effective cluster of the five investigated safety measures.
This project was therefore the first to evaluate the cost-effectiveness of a range of clustered safety measures for improving vulnerable road user (VRU) and car occupant protection via the HGV cab length derogations proposed in Directive (EU) 2015/719. The project performed a state-of-the-art review of exemplar and conceptual technologies relevant to HGVs with enhanced TFEDs. This was followed by a systematic review and critical appraisal of the literature to establish relevant target populations, effectiveness values and costs associated with each safety measure. The effects of clustering both the casualty reducing benefits and production related costs were then calculated for a total of 63 safety measure clusters, with the benefit-cost ratios of each individual safety measure and safety measure cluster ranked in order of cost-effectiveness. This was performed for two different approaches based on two separate fleet penetration models for enhanced TFEDs. These were a “uniform” approach, which assumed equal uptake across all HGV applications and vehicle types, and a “differentiated” approach, which assumed that articulated HGVs in long haulage operations would be the only sector to adopt cab length derogations. Finally, the potential regulatory options available for each individual safety measure were considered alongside the potential benefits and limitations of each option.
The benefit-cost ratios of all individual and clustered safety measures associated with the differentiated approach were found to be considerably lower than their equivalent values for the uniform approach. When considering the uniform approach a total of three individual safety measures were observed to be cost-effective (benefit-cost ratio ranges of >1), whilst a further five safety measure clusters were also found to be cost-effective (Table 1). When considering the differentiated approach, however, only a single safety measure, for front underrun protection (FUP), was observed to be cost-effective. For the uniform approach, the highest ranked cluster was found to be the sensor-based detection system safety measure. This was closely followed up by both a combination of the detection system and FUP safety measures and the FUP safety measure on its own, both of which may prevent a considerably larger proportion of killed or serious injuries.
Despite these significant outcomes, there were several limitations that could potentially affect the applicability and generalisability of these results. Firstly, although this project used, as best it could, an evidence base established on the current state-of-the-art in the research literature, a number of assumptions were made due to the paucity of relevant information. Key assumptions involved simplifying the benefit-cost analysis to discount the temporal trends associated with the HGV fleet, collision landscape and costs over the 10-year analysis period, the simplification of collision underreporting factors for the CARE database, the mapping of target populations between the safety measures in the same cluster, the exclusion of slight injuries, the assumption that all casualties are avoided rather than mitigated and the assumptions made when estimating the effectiveness of each safety measure.
This project further identified the regulatory options available to all safety measures. For each safety measure, all regulatory and standardised testing and assessment protocols underpinning each safety measure were considered to understand the changes needed to ensure the relevance of future regulatory requirements to HGVs with enhanced TFEDs. These concluded that the indirect vision and front underrun protection safety measures would require an update of the existing regulations (Regulations 46 and 93), whilst the remaining measures would require the development of new regulations adapted from the standardised protocols proposed within the HGV Direct Vision Standard (DVS) and Heavy Vehicles Aggressivity Index (HVAI) protocols.
Finally, the areas where further research should be performed to confirm the values used in this project were also identified. As a large proportion of effectiveness values were not based upon empirical evidence specific to the differences in performances between HGVs with regulated and unregulated TFEDs, primarily due to a paucity of research, the overall effectiveness values used within this project require confirmation. The costs used in this project were similarly affected, with further confirmation required for the cost ranges of each individual and clustered safety measure via industry stakeholder consultation. The target populations used by this project were less affected, but further research should be performed to evaluate the differences in outcome related to the differentiated approach.
Source: European Commission
In: Active safety, Passive safety, Safety