2003 Texas study concluded: "However, the actual reductions in speeds have been in the range of , which may be barely perceptible to the traveling public. There have been no studies that evaluate the reduction of excessive speeds." As a construction zone safety measure, the effectiveness appears unclear. A 2007 Minnesota study concluded that while transverse rumble strips offer a low cost and easy-to-install option, they “did not seem to be successful at reducing approach speeds at the project sites”. A 2005 Maryland study stated: "In conclusion, although in the present study rumble strips did not produce the desired speed reduction effect, its use for work zone applications is still highly encouraged; though, not as a speed control measure but as a driver's attention-catching device." As an approach stop-control crash reduction measure they have proven successful. The 2003 Texas indicated: "The majority of studies found reported large reductions (40% to 100%) of accidents after installing transverse rumble strips." In Ghana, rumble strips running across the entire carriageway were installed at Suhum Junction on the main Accra-Kumasi highway and reduced crashes by about 35% and fatalities by about 55%. By reducing speeds the environment for and safety of pedestrians was improved with a decline in the "hit pedestrian" crash rate of 51%. "While the enforcement of speed limits by traffic police may not be affordable for most developing countries, rumble strips and speed humps were found to be effective on Ghanaian roads." A 2009 FHWA intelligent systems study suggested that a combined infrastructure-based and in-vehicle warning could be highly effective in reducing crossing path crashes and fatalities at signalized intersections. Effectiveness Effectiveness of CSRS on different classes of highway Recent before-and-after studies suggest that the effectiveness of CSRS on Interstate highway (or freeways or thruways) with paved shoulders is about 7% to 21% with an overall effectiveness of about 14%. The effectiveness of CSRS on the lower-standard primary highways (that are also divided) has not been given the same consideration as those on Interstate highways. The 2003 Montana study suggested that CSRS on primary highways can result in either worsening or improvement of crash rates. This may be due to variation in recovery zone width and condition, and other factors. The study also stated that unprevented crash severity may worsen, and the overall results were inconclusive. The study suggested that the differences in rumble strip-related crashes between Interstate highways and primary