A new study conducted by the federal government shows that marijuana use may not have a serious impact on road safety. According to the Detroit News: The National Highway Traffic Safety Administration said a 20-month survey of drivers in 2013 and 2014 found that while drinking dramatically raises the chance of a crash, there was no evidence that marijuana use is statistically significant in boosting wreck rates. Marijuana users were about 25 percent more likely to be involved in a crash than drivers…