The Truck Cargo Heavy Duty (TCHD) carriers containing the weapons are escorted in a convoy of MoD vehicles commanded by a Ministry of Defence Police (MDP) Chief Inspector. The crew, of up to 50 people, includes a first aid team, fire crew and personnel equipped to monitor for radiological hazards. The convoy maintains contact by radio and telephone with Task Control, MDP Central Control Room, Wethersfield, Essex, which monitors its movement, and with the civil police forces in the affected areas.