Prior to German reunification in 1990, eastern German states focused on restrictive traffic regulation such as a autobahn speed limit and of on other rural roads. Within two years after the opening, availability of high-powered vehicles and a 54% increase in motorized traffic led to a doubling of annual traffic deaths, despite "interim arrangements involved the continuation of the speed limit of on autobahns and of outside cities". An extensive program of the four "E"s (enforcement, education, engineering, and emergency response) brought the number of traffic deaths back to pre-unification levels after a decade of effort while traffic regulations were conformed to western standards (e.g., freeway advisory limit, on other rural roads, and ).