<P> Typically motorways have higher speed limits than conventional roads because motorways have features which decrease the likelihood of collisions and severity of impacts . For example, motorways separate opposing traffic and crossing traffic, employ traffic barriers, and prohibit the most vulnerable users such as pedestrians and bicyclists . Germany's crash experience illustrates the relative effectiveness of these strategies on crash severity: on autobahns 22 people died per 1000 injury crashes, a lower rate than the 29 deaths per 1,000 injury accidents on conventional rural roads; however, the rural risk is five times higher than on urban roads--speeds are higher on rural roads and autobahns than urban roads, increasing the severity potential of a crash . The net effect of speeds, crash probability, and impact mitigation strategies may be measured by the rate of deaths per billion - travel - kilometers: the autobahn fatality rate is 2 deaths per billion - travel - kilometers, lower than either the 8.7 rate on rural roads or the 5.3 rate in urban areas; the overall national fatality rate was 5.6, slightly higher than urban rate and more than twice that of autobahns . </P> <P> The 2009 technical report An Analysis of Speeding - Related Crashes: Definitions and the Effects of Road Environments by the National Highway Traffic Safety Administration showed that about 55 percent of all speeding - related crashes in fatal crashes had "exceeding posted speed limits" among their crash factors, and 45 percent had "driving too fast for conditions" among their crash factors . However, the authors of the report did not attempt to determine whether the factors were actually a crash cause, contributor, or an unrelated factor . Furthermore, separate research finds that only 1.6% of crashes are "caused" by drivers that exceed the posted speed limit . Finally, exceeding the posted limit may not be a remarkable factor in crash analysis as there exist roadways where virtually all motorists are in technical violation of the law . </P> <P> The speed limit will also take note of the speed at which the road was designed to be driven (the design speed) which is defined in the US as "a selected speed used to determine the various geometric design features of the roadway" However traffic engineers recognize that "operating speeds and even posted speed limits can be higher than design speeds without necessarily compromising safety" since design speed is "based on conservative assumptions about driver, vehicle and roadway characteristics". </P> <P> Vision Zero, which envision reducing road fatalities and serious injuries to zero by 2020, suggests the following "possible long term maximum travel speeds related to the infrastructure, given best practice in vehicle design and 100% restraint use": </P>

What is the speed limit in the rain