Gravel road embankments in low-lying areas. Cellular confinement systems can be used to prevent the washboarding effect. The gravel used consists of varying amount of crushed stone, sand, and "fines". Fines are silt or clay particles smaller than , which can act as a binder. Crushed stone is used because gravel with fractured faces will stay in place better than rounded river pebbles. A good gravel for a gravel road will have a higher percentage of fines than gravel used as a subbase for a paved road. This often causes problems if a gravel road is paved without adding sand and gravel
Mike Gravel Washington, D.C. Short on campaign cash, he took public transportation to get to his announcement. (Gravel called for public financing of elections.) Other principal Gravel positions were the FairTax, withdrawal of U.S. troops from Iraq within 120 days, a single payer national health care system, and term limits. In particular, he had opposed the Iraq War from the beginning, and in 2006 Gravel said that U.S. troops in Iraq, as in Vietnam, had "died in vain". He also favored a regional peace initiative, as well as reparation payments for Iraqis. Gravel also called for a "U.S. corporate withdrawal from Iraq",