pedestrian areas, speed bumps are often placed to slow cars, preventing them from going too fast near pedestrians. poor road surfaces can lead to safety problems. if too much asphalt or bituminous binder is used in asphalt concrete, the binder can 'bleed' or flush' to the surface, leaving a very smooth surface that provides little traction when wet. certain kinds of stone aggregate become very smooth or polished under the constant wearing action of vehicle tyres, again leading to poor wet-weather traction. either of these problems can increase wet-weather crashes by increasing braking distances or contributing to loss of control. if the pavement is insufficiently sloped or poorly drained, standing water on the surface can also lead to wet-weather crashes due to hydroplaning. lane markers in some countries and states are marked with cat's eyes, botts' dots or reflective raised pavement markers that do not fade like paint. botts dots are not used where it is icy in the winter, because frost and snowplows can break the glue that holds them to the road, although they can be embedded in short, shallow trenches carved in the roadway, as is done in the mountainous regions of california. road hazards and intersections in some areas are now usually marked several times, roughly five, twenty, and sixty seconds in advance so that drivers are less likely to attempt violent manoeuvres. most road signs and pavement marking materials are retro-reflective, incorporating small glass spheres or prisms to more efficiently reflect light from vehicle headlights back to the driver's eyes. turning across traffic turning across traffic (i.e., turning left in right-hand drive countries, turning right in left-hand drive countries) poses several risks. the more serious risk is a collision with oncoming traffic. since this is nearly a head-on collision, injuries are common. it is the most common cause of fatalities in a built-up area. another major risk is involvement in a rear-end collision while waiting for a gap in oncoming traffic. countermeasures for this type of collision include: addition of left turn lanes providing protected turn phasing at signalized intersections using indirect turn treatments such as the michigan left converting conventional intersections to roundabouts in the absence of these facilities as a driver about to turn: keep your wheels straight, so that in the event of a rear end shunt, you are not pushed into on-coming traffic. when you think it is clear, look away, to the road that you are entering. there is an optical illusion that, after a time, presents an oncoming vehicle as further away and travelling slower. looking away breaks this illusion. there is no presumption of negligence which arises from the bare fact of a collision at an intersection, and circumstances may dictate that a left turn is safer than to turn right. the american association of state highway transportation officials (aashto) recommends in their publication geometric design of highways and streets that left or right turns are to be provided the same time gap. some states have recognized this in statute, and a presumption of negligence is only raised because of the turn if and only if the turn was prohibited by an erected sign. turns across traffic have been shown to be problematic for older drivers. designing for pedestrians and cyclists pedestrians and cyclists are among the most vulnerable road users and in some countries constitute over half of all road deaths. interventions aimed at improving safety of non-motorised users: sidewalks (or pavements in british english) of suitable width for pedestrian traffic pedestrian crossings close to the desire line which allow pedestrians to cross roads safely segregated pedestrian routes and cycle lanes away from the main highway overbridges (tend to be unpopular with pedestrians and cyclists due to additional distance and effort) underpasses (these can pose heightened risk from crime if not designed well, can work for cyclists in some cases) traffic calming and speed humps low speed limits that are rigorously enforced, possibly by speed cameras shared space schemes giving ownership of the road space and equal priority to all road users, regardless of mode of use pedestrian barriers to prevent pedestrians crossing dangerous locations cycling infrastructure protected intersection american passive traffic safety measures which were adopted in the mid-20th century created roadways which were forgiving to motorists traveling at high speeds but which de-prioritized cycling and pedestrian facilities. passive traffic safety policies led to excessively wide streets, clear zones adjacent to roadways, wide turn radii and a focus on protecting drivers from the consequences of high speeds. passive traffic safety measures sought to avoid influencing the behavior of drivers while giving automobiles maximum convenience. recent complete street policies seek to create design-oriented traffic safety improvements which actively slow drivers down by narrowing roadways while better accommodating pedestrians and cyclists. pedestrians' advocates question the equitability of schemes if they impose extra time and effort on the pedestrian to remain safe from vehicles, for example overbridges with long slopes or steps up and down, underpasses with steps and addition possible risk of crime and at-grade crossings off the desired crossing line. make roads safe was criticised in 2007 for proposing such features. successful pedestrian schemes tend to avoid over-bridges and underpasses and instead use at-grade crossings (such as pedestrian crossings) close to the intended route. successful cycling schemes by contrast avoid frequent stops even if some additional distance is involved, because cyclists expend more energy when starting off. in costa rica 57% of road deaths are pedestrians. however, a partnership between aacr, cosevi, mopt and irap has proposed the construction of 190 km of pedestrian footpaths and 170 pedestrian crossings which could save over 9000 fatal or serious injuries over 20 years. safe from traffic for cycling along a fully segregated fietspad, properly designed cycling infrastructure in amsterdam shared space a shared space in brighton (uk) by 1947 the pedestrians' association was suggesting that many of the safety features being introduced (speed limits, traffic calming, road signs and road markings, traffic lights, belisha beacons, pedestrian crossings, cycle lanes, etc.) were potentially self-defeating because "every nonrestrictive safety measure, however admirable in itself, is treated by the drivers as an opportunity for more speeding, so that the net amount of danger is increased and the latter state is worse than the first." during the 1990s a new approach, known as 'shared space' was developed which removed many of these features in some places has attracted the attention of authorities around the world. the approach was developed by hans monderman who believed that "if you treat drivers like idiots, they act as idiots" and proposed that trusting drivers to behave was more successful than forcing them to behave. professor john adams, an expert on risk compensation suggested that traditional traffic engineering measures assumed that motorists were "selfish, stupid, obedient automatons who had to be protected from their own stupidity" and non-motorists were treated as "vulnerable, stupid, obedient automatons who had to be protected from cars – and their own stupidity". reported results indicate that the 'shared space' approach leads to significantly reduced traffic speeds, the virtual elimination of road casualties, and a reduction in congestion. living streets share some similarities with shared spaces. the woonerven also sought to reduce traffic speeds in community and housing zones by the use of lower speed limits enforced by the use of special signage and road markings, the introduction of traffic calming measures, and by giving pedestrians priority over motorists. non-built-up areas roads outside built-up areas, also known as rural roads not including motorways, are roads which are not classified as urban road and which are not classified as motorway. in the european union, this is the kind of road with the most people killed (54.3%) in 2015, more than inside urban areas (36.8%). however such numbers might change country by country. fatalities on the rural roads come from the many collisions due to the dangers that exist on such roads, and the important energy involved in those collisions due to the practiced speeds. in contrast, risks of collision are less numerous on motorways, and speeds are lower on rural roads. major highways guard rail on road in kaluga oblast (russia) the pan-american highway with central median and no freestanding obstructions major highways including motorways, freeways, autobahnen and interstates are designed for safer high-speed operation and generally have lower levels of injury per vehicle km than other roads; for example, in 2013, the german autobahn fatality rate of 1.9 deaths per billion-travel-kilometers compared favorably with the 4.7 rate on urban streets and 6.6 rate on rural roads. safety features include: limited access from the properties and local roads. grade separated junctions median dividers between opposite-direction traffic to reduce likelihood of head-on collisions removing roadside obstacles. prohibition of more vulnerable road users and slower vehicles. placements of energy attenuation devices (e.g. guard rails, wide grassy areas, sand barrels). eliminating road toll booths the ends of some guard in rails on high-speed highways in the united states are protected with impact attenuators, designed to gradually absorb the kinetic energy of a vehicle and slow it more gently before it can strike the end of the guard rail head on, which would be devastating at high speed. several mechanisms are used to dissipate kinetic energy. fitch barriers, a system of sand-filled barrels, uses momentum transfer from the vehicle to the sand. many other systems are tear or deform steel members to absorb energy and gradually stop the vehicle. in some countries major roads have "tone bands" impressed or cut into the edges of the legal roadway, so that drowsing drivers are awakened by a loud hum as they release the steering and drift off the edge of the road. tone bands are also referred to as "rumble strips", owing to the sound they create. an alternative method is the use of "raised rib" markings, which consists of a continuous line marking with ribs across the line at regular intervals. they were first specially authorised for use on motorways as an edge line marking to separate the edge of the hard shoulder from the main carriageway. the objective of the marking is to achieve improved visual delineation of the carriageway edge in wet conditions at night. it also provides an audible/vibratory warning to vehicle drivers, should they stray from the carriageway, and run onto the marking. better motorways are banked on curves to reduce the need for tire-traction and increase stability for vehicles with high centers of gravity. the us has developed a prototype automated roadway, to reduce driver fatigue and increase the carrying capacity of the roadway. roadside units participating in future wireless vehicle safety communications networks have been studied. motorways are far more expensive and space-consumptive to build than ordinary roads, so are only used as principal arterial routes. in developed nations, motorways bear a significant portion of motorized travel; for example, the united kingdom's 3533 km of motorways represented less than 1.5% of the united kingdom's roadways in 2003, but carry 23% of road traffic. the proportion of traffic borne by motorways is a significant safety factor. for example, even though the united kingdom had a higher fatality rates on both motorways and non-motorways than finland, both nations shared the same overall fatality rate in 2003. this result was due to the united kingdom's higher proportion of motorway travel. similarly, the reduction of conflicts with other vehicles on motorways results in smoother traffic flow, reduced collision rates, and reduced fuel consumption compared with stop-and-go traffic on other roadways. the improved safety and fuel economy of motorways are common justifications for building more motorways. however, the planned capacity of motorways is often exceeded in a shorter timeframe than initially planned, due to the under estimation of the extent of the suppressed demand for road travel. in developing nations, there is significant public debate on the desirability of continued investment in motorways. with effect from january 2005 and based primarily on safety grounds, the uk's highways agency's policy is that all new motorway schemes are to use high containment concrete step barriers in the central reserve. all existing motorways will introduce concrete barriers into the central reserve as part of ongoing upgrades and through replacement as and when these systems have reached the end of their useful life. this change of policy applies only to barriers