There is no specific mention of speed limits and signboards in the Factories Act. Provisions for safety and health are given in detail. Rules framed under these safety provisions can easily include speed limits in factory premises, no-entry zones, parking areas, and speed breakers, etc.
Please go ahead and frame speed limits, no-entry without helmets, and a policy on checking driver licenses for outside vehicles, Pollution Under Control (PUC) certificates, vehicle insurance of contractor vehicles entering your factory premises.