The illumination quality of a motorcycle lighting system is essential for safety and driving comfort. In this paper, we propose a light-emitting diode (LED) motorcycle low-beam headlamp based on a freeform reflector. The reflector is generated by a freeform optics design method. Then, the optical system is simulated by the Monte Carlo method using commercial optical tracing software. The low-beam headlamp is then fabricated and assembled into a physical object. Both the simulation and measurement results show that the headlamp fully complies with United Nations Economic Commission for Europe (ECE) vehicle regulations.

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Crash prediction of the sharp horizontal curve segment (SHCS) of a freeway is an important tool in analyzing safety of SHCSs and in building a crash prediction model (CPM). The design and crash report data of 88 SHCSs from different institutions were surveyed and three negative binomial (NB) regression models and three generalized negative binomial (GNB) regression models were built to prove that the interactive influence of explanatory variables plays an important role in fitting goodness. The study demonstrates the effective use of the GNB model in analyzing the interactive influence of explanatory variables and in predicting freeway basic segments. Traffic volume, highway horizontal radius, and curve length have been formulated as explanatory variables. Subsequently, we performed statistical analysis to determine the model parameters and conducted sensitivity analysis. Among the six models, the result of model 6, which considered interactive influence, is much better than those of the other models by fitting rules. We also compared the actual results from crashes of 88 SHCSs with those predicted by models 1, 3, and 6. Results demonstrate that model 6 is much more reasonable than models 1 and 3.