Compliance and violation behavior of drivers at one of three vehicle arresting barriers (VABs) in Illinois is presented. VABs are traffic control and safety devices that function as an impenetrable barrier to highway vehicles at railroad grade crossings on high-speed passenger rail corridors. Driver behavior on approach and at the VABs is analyzed to determine compliance and violation behaviors regarding this new device and related signage and signals. During 1999, the first year of operation, the VABs were in operation less than 50 percent of their scheduled time. This diminished the expected data and definable periods for study of driver behavior. Only one site had sufficient data to initiate a qualitative analysis of compliance and violation rates. The early findings suggest that drivers showed less risk-taking behavior during the initial period of operation and that compliance levels were slightly better than those of other innovative highway-rail safety devices studied in recent years. However, over time, the lengthy advanced flashing light warning time, inconsistent and problematic operating profile, and general driver familiarity appear to have led to system credibility and driver compliance issues with the barrier system.
Models of varying degree of sophistication are used in vehicle dynamic studies. For ride comfort, Kelvin–Voigt arrangement is preferred and for impact harshness analysis, a relaxation-type suspension model, Zener or Maxwell type is used. The nonconsideration of relaxation-type models in ride comfort studies can result in significant errors for frequencies below ∼30 Hz. The object of the paper is to show the influence of the series stiffness on the effective suspension damping both experimentally and numerically. A frequency domain analysis of two-degree of freedom Zener quarter car model is performed to find the complex relation between effective damping coefficient and the limiting value of damping ratio for a given series stiffness. The nonlinear relation between shock absorber damping and the natural frequencies is clearly illustrated. A novel four-post rig set-up is used to validate the results by measuring transmissibilities, giving damping ratios for varying shock absorber settings. A closed form solution, based on a simplified partial model, of optimal damping coefficient, which is a nonlinear function of stiffnesses, shows good agreement with numerical simulations of the complete system. The nonlinearities in shock absorbers also influence the outcome. These findings can be a great value at early design stage.
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