This paper proposes from fundamental mechanics that the specific energy ( E/ M) absorption characteristics of motorcycles and scooters in frontal impacts are similar where the primary load path is through the front wheel and fork assembly. Examination of 43 barrier test results for 14 different model types of motorcycle and scooter over the impact speed range from 10km/h to 76km/h shows that the specific energy versus wheelbase shortening characteristics are similar and that a single specific collision energy ( E/ M) regression equation with its associated statistical distribution ( r2=0.845) can be used to represent the motorcycle and scooter populations in frontal impact for wheelbase shortening up to 0.45m where the front-fork and front-wheel assemblies remain intact, albeit deformed. Data from 31 staged tests where motorcycles or scooters impacted stationary cars at 90° are used to obtain the energy absorption characteristics of the sides of cars subject to frontal motorcycle or scooter impact. These two regressions are used to estimate collision energy Eca from the permanent deformation or penetration depth of the collision partners, which, when substituted into the standard impact energy loss equation with the appropriate collision partner masses, yields an estimation of collision speed Vccs. This procedure for calculating collision closing speed Vccs is validated against 13 staged tests (six 90° impacts against stationary cars and seven angled impacts at angles up to 45° from the normal, four of which were against moving cars) and shows that the predicted Vccs speeds bound the actual speeds with a standard deviation of 11.2km/h for collision closing speeds up to 122km/h.

In many motorcycle accidents, the motorcycle falls to the ground and slides to rest following impact or loss of control. The determination of the motorcycle speed just prior to ‘fall-over’ is important for biomechanics research and for litigation. This paper presents a new model of motorcycle fall-over and slide, which accounts for the loss of horizontal momentum resulting from the initial motorcycle-to-ground impact and the subsequent slide to rest. The model includes cases involving motorcycle fall-over owing to loss of control as well as impact. The models represent both the mean and variation present in the available experimental data for dry roads very well and are used to develop confidence limits for accident reconstruction purposes, in cases where only the motorcycle slide distance along the ground is known. Previously proposed confidence limit criteria are applied to predicting motorcycle speed ranges from slide distance, and it is shown that the level of prediction uncertainty can be substantially reduced in cases where additional information specific to the vehicle and road configurations is available.

It has been demonstrated in previous research that the collision closing speed in a collision of a motorcycle or scooter with a car can be estimated on the basis of the residual crushing damage shared between the two vehicles, using an energy-derived relationship between the residual crushing damage and the collision closing speed. This paper reviews the original research and develops two further models that allow independent estimates of the collision closing speed to be calculated on the basis of either the residual deformation to the motorcycle or the residual deformation to the car. The models are validated from further crash test data taken from the literature. The principal results of the analyses are presented in the form of two predictive equations, together with the associated uncertainty that arises from the nature of the various constructions and stiffnesses of the vehicles within the population fleet. Comparison is made with other analyses in the literature. Further consideration is given to deviations from the mean estimate for subsets of the fleet population, taking into account the fact that the sides of cars have portions of various stiffnesses and that the mean stiffness of the sides of cars differed historically from those of modern models. Correction factors are presented which allows for a refined prediction based on the vehicle age and the car impact location.

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This paper presents a new physical model for estimating motorcycle speed in motorcycle to car collisions from the motorcycle wheelbase reduction and car deformation depth. This model combines previously published specific energy characteristics of motorcycles and scooters derived from barrier tests with a motorcycle to car interface ForceÀBalance approach to estimate the collision energy absorbed by the car. This ForceÀBalance approach and three previously published models for motorcycle speed estimation are compared using a data-set of 107 published staged collisions, over a collision speed range of 30À122 kph. The ForceÀBalance model and a previously published empirical model were shown to compare well with the available staged tests, with statistically insignificant mean residuals of 0.8 and 0.7 kph for the predicated speed when compared with actual speeds. The corresponding standard errors were 10.3 and 11.2 kph, respectively. Two other previously published physical models were shown to significantly under-predict speed, with mean residuals of 5.6 and 19.5 kph, respectively, with corresponding standard errors of 9.5 and 11.8 kph. An analysis of impacts into hard and soft areas of the car sides show that the presented ForceÀBalance model is robust when applied to both soft and hard impact locations, while the empirical approach is shown to be robust for soft impact locations but under-predicts collision speed by a mean of 3 kph for hard impact locations.