As a school bus comes to a halt on a busy street, the driver swings out the vehicle's stop arm and turns on flashing red lights. Most drivers know what those signals mean--they are required by law to stop their vehicles so that children can safely cross the thoroughfare. However, many drivers simply choose to ignore the law. Thousands of motorists, impatient or just reckless, have illegally passed a stopped bus and jeopardized the safety of students. Unless the offending driver can be identified, it can be difficult for authorities to make a case. However, that is no longer a problem in the Liberty (Missouri) school district. The 8,500-student district has equipped its buses with a four-camera system that includes a unit on the stop arm itself. With these stop-arm cameras, the license number and the face of the driver can be identified. The stop-arm cameras are just one example of how schools and universities are taking advantage of technological improvements to provide safer campuses. Innovations such as digital cameras, biometric access-control systems, global positioning systems and radio-frequency ID tags help ensure that campuses are better protected.