for safety reasons, the United States Bureau of Reclamation restricts the type of vehicles that can drive across the top of Hoover Dam. The restrictions generally are limited to commercial buses and trucks. All vehicles crossing the dam must be inspected at checkpoints on each side of the dam.
All passenger vehicles with a cargo capacity of one ton or less are allowed to cross Hoover Dam, subject to inspections. That includes automobiles; light trucks; vans; sport utility vehicles; motorcycles; tractor-trailor trucks without the trailers (known as bob-tails); recreational vehicles and motor-homes; buses not carrying luggage; vehicles towing campers, small trailers, boats or non-commercial livestock trailers; tow trucks; rental trucks; military convoys with police approval; and larger trucks with proper permits.
Vehicles not allowed to drive across Hoover Dam include all commercial 18-wheel semi-trucks except those with proper permits; buses carrying luggage; enclosed moving vans or enclosed box-type trucks; double-stacked trailers; vehicles that cannot be opened for inspection; and vehicles carrying hazardous or flammable materials, ammunition, explosives, more than 40 pounds of fertilizer or any other cargo that inspectors think is a security risk.
Vehicle restrictions and checkpoints were established for Hoover Dam traffic after the September 11, 2001, terrorist attacks. The two checkpoints are located on Highway 93, 1 mile north of the dam in Nevada and 9 miles south of the dam in Arizona. All drivers of approved vehicles crossing the dam must stop at both checkpoints and be prepared for vehicles to be inspected or searched by security officers.
Drivers of vehicles prohibited from crossing Hoover Dam, or those who do not want their vehicles inspected, can take alternate routes. One alternative takes drivers along United States Highway 95 and state routes 163 and 68 through Laughlin, Nevada, and Bullhead City, Arizona.
The Hoover Dam Bypass Project, expected to be completed in late 2010, is a 3.5-mile alternative route that crosses the Colorado River 1,500 feet downstream from the Hoover Dam.
Dam operators suggest the best times to cross the dam are before 10 a.m. and after 3 p.m. local time. Traffic is typically heaviest between 11 a.m. and 3 p.m. and during holidays or weekends. The busiest months are in the summer and during school spring-break periods in late March and early April.
No stopping is allowed on the dam, but visitors can park in turnouts on each side of the dam for sight-seeing. Pedestrians are prohibited on the dam after dark.
Thousands of engineers and laborers built the Hoover Dam in less than five years. When construction ended in 1936, the dam was the largest hydroelectric generation plant and largest concrete structure in the world. Water backing up behind it created Lake Mead. The American Society of Civil Engineers named Hoover Dam one of America's Seven Modern Civil Engineering Wonders. The dam has National Historic Landmark status.
