Taking recommended doses of several drugs together, which individually do not cause impairment, may combine to bring on drowsiness or other impairment. This could be more pronounced in an elderly person whose renal function is less efficient than a younger persons.Thus, there are situations when a person may be impaired, but still legally allowed to drive, and becomes a potential hazard to themselves and other road users. Pedestrians or cyclists are affected in the same way and can similarly jeopardize themselves or others when on the road. Road design
A 1985 US study showed that about 34% of serious crashes had contributing factors related to the roadway or its environment. Most of these crashes also involved a human factor. The road or environmental factor was either noted as making a significant contribution to the circumstances of the crash, or did not allow room to recover. In these circumstances, it is frequently the driver who is blamed rather than the road; those reporting the collisions have a tendency to overlook the human factors involved, such as the subtleties of design and maintenance that a driver could fail to observe or inadequately compensate for.Research has shown that careful design and maintenance, with well-designed intersections, road surfaces, visibility and traffic control devices, can result in significant improvements in collision rates. Individual roads also have widely differing performance in the event of an impact.
United Kingdom
In the United Kingdom, the Pre-Action Protocol for Low Value Personal Injury Claims in Road Traffic Accidents from 31 July 2013, otherwise known as the RTA Protocol,describes the behaviour the court expects of the parties prior to the start of proceedings where a claimant claims damages valued at no more than the Protocol upper limit as a result of a personal injury sustained by that person in a road traffic accident. As of February 2022 the "upper limit" is £25,000 for an accident which occurred on or after 31 July 2013; the limit under a previous version of the protocol was £10,000 for an accident which had occurred on or after 30 April 2010 but before 31 July 2013. United States
Motor vehicle crashes are the leading cause of death in the workplace in the United States accounting for 35 percent of all workplace fatalities. In the United States, individuals involved in motor vehicle collisions may be held financially liable for the consequences of a collision, including property damage, and injuries to passengers and drivers. Where another drivers vehicle is damaged as the result of a crash, some states allow the owner of the vehicle to recover both the cost of repair for the diminished value of the vehicle from the at-fault driver. Because the financial liability that results from causing a crash is so high, most U.S. states require drivers to carry liability insurance to cover these potential costs.