In most countries, road accidents are usually causing more injuries and casualties than any other natural or man-made hazard. Among various causes of crashes, excessive speeds and adverse environments were found as the two dominant causes to the road accidents. In addition to direct safety threats, frequent vehicle accidents will also cause serious congestions of the whole highway network in normal situations. Therefore, it is critical to accurately predict the crash risk and further advise appropriate driving speeds under complicated adverse driving environments. Ride safety of the moving...