Access control Brent Gunderson, regional security manager of the lower Colorado river region, worked at the Hoover Dam for four years and managed the police force. He spends two days each week at the Hoover in meetings to discuss how to improve security functions. We talked to him about security and access at the site, deemed one of America's Seven Modern Civil Engineering Wonders by the American Society of Civil Engineers.CSO: What security changes have been made at the Hoover Dam since 9\/11?Gunderson: We have installed vehicle checkpoints; one on the Nevada side, and one on the Arizona side. We also now prohibit commercial traffic access across the dam, with the exception of some local businesses. These businesses can request a permit to cross the dam during daylight hours. All other commercial trafficspecifically, the large semis and busesare not allowed to cross and are turned around at the checkpoints. Private vehicles are allowed to cross after the vehicle is inspected. Another change is the modification of tour routes. The traditional and hard-hat tours were discontinued, and we now have more "top of dam" free tours with limited tour access into the dam itself. The Hoover Dam Police force has expanded to accommodate the security measures implemented.Who has access to the dam?Primarily employees and contractors, who must meet specific security restrictions. We no longer allow access to the interior of the dam by movie companies. All visitors, or anyone doing business at the dam, are required to pass through magnetometers and X-ray screening.What's the process to get a permit? Is there a security background check?The company requesting a permit lists its point of origin and delivery, submits a listing of its drivers, and provides appropriate detailed information such as driver's license number, complete with photo. And then, a background check is done. The company listings and photos are matched at the checkpoint. If the two don't match, the vehicle is turned away. Basically, the permit allows passage over the dam during daylight hours, when the permit is presented along with the driver's license. The permit allows them to show up. They are then inspected and allowed to pass. Do you search trucks?We inspect vehicles, whether full or empty. We inspect all "closed" vehicles, large trucks, buses and RVs 100 percent of the time. Anyone who doesn't allow inspection of their vehicle is turned around.How much money has been allotted to secure the dam?Approximately $5.5 million per year is allocated to all security, including law enforcement. Additional money is allocated for security work on the structure and facilities.What are your future security plans? To continue to implement the measures necessary to protect and harden, as appropriate, the dam and surrounding structures.