Simulation study: falling behaviour of speed-pedelec riders

Speed-pedelecs are an uprising type of electric bicycles that can increase the riders peddling power to achieve cycling speeds up to 45 km/h. In the Dutch law, speedpedelecs are classified as mopeds. The Dutch minister of Infrastructure and Environment has announced that no exceptions on the moped regulations will be made for speed-pedelec-riders in the Netherlands as soon as the new European Legislation (‘kaderverordening’) stands (January 2017). This means that speedpedelec riders will be obliged to wear a helmet that meets the ECE 22-05 standard. This decision was based on the fact that moped-riders and speed-pedelec-riders have the same allowed maximum speed, and as such they need the same level of protection. The helmets fulfilling the ECE 22-05 standard that are currently on the market are designed for moped- and motorcycle-riders. The Dutch speed-pedelec industry is afraid that the helmets prescribed by the proposed regulations will discourage people to buy a speed-pedelec, and on the other hand, doubts whether a bicycle helmet can offer sufficient protection. The bicycle helmet regulation EN1078 was deduced from the motor-helmet regulation, giving more room for ventilation with concessions to the protection level. TNO investigated for the Dutch speed-pedelec industry the difference between the moped helmet regulation (ECE 22-05) and the bicycle helmet regulation (EN 1078) [10]. The Dutch Ministry of Infrastructure and Environment would like to understand on a short term whether beside the ECE 2205 an alternative exists which can offer appropriate protection to the speed-pedelec rider offering a solution for 2017. If a safe alternative can be guaranteed, the Minister could reconsider her earlier decision. In case the Netherlands want to deviate from the European Legislation the Ministry of Infrastructure and Environments needs proper justification. Therefore, the Dutch Ministry of Infrastructure and Environment asked TNO to perform a study to obtain, on short term, a first insight on the required level of headprotection for speed-pedelec riders. TNO performed a simulation study using available human models in the software package MADYMO. In this study the falling behaviour in single sided accidents of speed-pedelec riders, was compared to that of moped drivers and cyclists. It is believed that a speed-pedelec helmet should be able to give appropriate protection against head injury for single sided accidents. Three common types of single sided two-wheeler-accident configurations have been selected and simulated. Further, a small set of variations of the conditions (operational velocity, friction of the ground, cause of the fall) have been taken into account. The falling mechanism as well as a selected set of head injury causation parameters were investigated and related to the helmet test parameters. The conclusions of this study are as follows: In general higher initial velocities mainly result in higher head impact velocities and consequently a higher head impact level. Whether this high impact level is reached depends on the actual falling mechanism. In case the impact-energy of the fall is absorbed by the head first, high impact levels are reached. If the fall is broken, for example by other body parts touching the ground first or by hooking of the body to the frame of the bicycle, the impact level will not reach the high impact levels. More simulations and parameter variations are needed to come up with quantitative conclusions on the impact levels. Based on the results of this study, TNO advices to base the required head protection level on the high impact levels, so where the fall of the head is not broken, in order to protect speed-pedelec riders well. Since the operational speed of speed-pedelec riders is higher than that of the cyclists, they need a higher level of protection. More research is needed to quantify the actual protection level. • A large variety in head impact locations is observed, ranging from the face, to top and side of the head. The variety is in line with the results of the study of the GDV [8] where the head impact locations of cyclists were studied. Further, it is known that the side of the head around the ears is more fragile than the front or top of the head [9] as the skull is less thick at that location. Based on these results, TNO advises to also protect the speed-pedelec riders head around the ears. • No clear pattern could be found in the head movements after impact. Different movements are observed, ranging from full sliding, rotating, bouncing and combinations thereof. Therefore, TNO advises a helmet surface that could deal with sliding, rotating and bouncing, requiring a smooth surface with holes for ventilation that will not cause hooking into.