Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel. Traffic laws are the laws which govern traffic and regulate vehicles, while rules of the road are both the laws and the informal rules that may have developed over time to facilitate the orderly and timely flow of traffic.
Organized traffic generally has well-established priorities, lanes, right-of-way, and traffic control at intersections.
Law enforcement broadly refers to any system by which some members of society act in an organized manner to enforce the law by discovering and punishing persons who violate the rules and norms governing that society. Although the term may encompass entities such as courts and prisons, it is most frequently applied to those who directly engage in patrols or surveillance to dissuade and discover criminal activity, and those who investigate crimes and apprehend offenders. Furthermore, although law enforcement may be most concerned with the prevention and punishment of crimes, organizations exist to discourage a wide variety of non-criminal violations of rules and norms, effected through the imposition of less severe consequences.
Most law enforcement is conducted by some type of law enforcement agency, with the most typical agency fulfilling this role being the police. Societal investment in enforcement through such organizations can be massive, both in terms of the resources invested in the activity, and in the number of people professionally engaged to perform those functions.
Road traffic safety refers to methods and measures for reducing the risk of a person using the road network being killed or seriously injured. The users of a road include pedestrians, cyclists, motorists, their passengers, and passengers of on-road public transport, mainly buses and trams. Best-practice road safety strategies focus upon the prevention of serious injury and death crashes in spite of human fallibility (which is contrasted with the old road safety paradigm of simply reducing crashes assuming road user compliance with traffic regulations). Safe road design is now about providing a road environment which ensures vehicle speeds will be within the human tolerances for serious injury and death wherever conflict points exist. Furthermore, the highest possible degree of safety shall be ensured when transporting goods by road. It is of vital importance to monitor and validate the road transportation safety, including comprehensive checks on drivers, vehicles and safety processes.
The basic strategy of a Safe System approach is to ensure that in the event of a crash, the impact energies remain below the threshold likely to produce either death or serious injury. This threshold will vary from crash scenario to crash scenario, depending upon the level of protection offered to the road users involved. For example, the chances of survival for an unprotected pedestrian hit by a vehicle diminish rapidly at speeds greater than 30 km/h, whereas for a properly restrained motor vehicle occupant the critical impact speed is 50 km/h (for side impact crashes) and 70 km/h (for head-on crashes).
Road speed limits are used in most countries to regulate the speed of road vehicles. Speed limits may define maximum (which may be variable), minimum or no speed limit and are normally indicated using a traffic sign. Speed limits are commonly set by the legislative bodies of nations or provincial governments and enforced by national or regional police and / or judicial bodies.
The first maximum speed limit was the 10 mph (16 km/h) limit introduced in the United Kingdom in 1861. Highest speed limit in the world is 140 km/h (87 mph), which applies to some roads in Abu Dhabi , Poland and Bulgaria; similarly Texas posts 85 mph (137 km/h) on one 40-mile long toll road. However, some roads have no speed limit for certain classes of vehicles. Best known are Germany's less congested Autobahns, where automobile drivers have no mandated maximum speed; measurements from the German State of Brandenburg in 2006 showed average speeds of 142 km/h (88 mph) on a 6-lane section of autobahn in free-flowing conditions. Rural areas on the Isle of Man, the Indian states of Andhra Pradesh and Maharashtra also lack speed limits, but speeds are lower when measured on those lower design roads.
The National Maximum Speed Law (NMSL) in the United States was a provision of the 1974 Emergency Highway Energy Conservation Act that prohibited speed limits higher than 55 miles per hour (89 km/h). It was drafted in response to oil price spikes and supply disruptions during the 1973 oil crisis.
While officials hoped gasoline consumption would fall by 2.2%, actual savings are estimated at between 0.5% and 1%.
Speed limits in the United States are set by each state or territory. Speed limits are always posted in increments of five miles per hour. Some states have lower limits for trucks and at night, and occasionally there are minimum speed limits. Most speed limits are set by state or local statute, although each state allows various agencies to set a different, generally lower, limit.
The highest speed limits are generally 75 mph (121 km/h) in western states and 70 mph (113 km/h) in eastern states. A few states, mainly in the Northeast Megalopolis, have 65 mph (105 km/h) limits, and Hawaii only has 60 mph (97 km/h) maximum limits. A small portion of the Texas and Utah road networks have higher limits. For 13 years (1974–1987), federal law prohibited speed limits above 55 mph (89 km/h).
The International Isle of Man TT (Tourist Trophy) Race is a motorcycle racing event held on the Isle of Man that was for many years the most prestigious motorcycle race in the world and remains statistically the most dangerous race in the world. The event was part of the FIM Motorcycle Grand Prix World Championship during the period 1949–1976 before being transferred to the United Kingdom after safety concerns and run by the FIM as the British Grand Prix for the 1977 season. The Isle of Man TT Races became part of the TT Formula 1 Championship from 1977 to 1990 to preserve the event's racing status. From 1989 the racing has been developed by the Isle of Man Department of Tourism as the Isle of Man TT Festival.
The race is run in a time-trial format on public roads closed for racing by the provisions of an Act of Tynwald (the parliament of the Isle of Man). The first race was held on Tuesday 28 May 1907 and was called the International Auto-Cycle Tourist Trophy. The event was organised by the Auto-Cycle Club over 10 laps of the St John's Short Course of 15 miles 1,470 yards for road-legal touring motorcycles with exhaust silencers, saddles, pedals and mud-guards.