Hi Doug

The Department of Labour in their Occupational Safety General Regulations, for the province of Nova Scotia, Canada requires lift trucks to have "an audible back up alarm or equivilant safety device" inatalled. You may want to consult your local regulations. When teaching driver training classes I stress to all students the importance of watcing for pedestrians and encourage managers and employers to do safety audits and stress pedestrian safety courses.
It is worth the cost of having a competent professional consultant spend time at your facility in conjunction with your health and safety committee assesing oportunities for improved lift truck safety.