No escort is required for loads up to and including 12 feet 4 inches in width. Escort requirements for loads exceeding 12 feet 4 inches in width are in following sections.
12 feet 4 inches - 14 feet: One escort required for each overdimension unit on the interstate and designated routed system. This escort shall be in the rear on dual lane divided or multi-lane pavement and in the front on two lane pavement. Travel on routes off interstate and designated route system will require two escorts (front and rear). Two-way radios required in the power unit and all escort vehicles.
Over 14 feet: One escort is required in the rear on interstate and other divided highways. Two escorts are required on all multi-lane undivided and two-lane highways, one front and one rear. Two-way radio communication is required between the power unit and all escort vehicles.
A rear escort is required for movements when the vehicle and load exceed 90 feet for a combination unit on all highways except divided highways; and
Special escort requirements may be specified whenever the size, speed or operation of movement may require. A separate escort shall be provided for each load and movement in convoy is not allowed.
The following regulations apply to escorts and flagmen and it is the responsibility of the permit applicant to see that escorts which accompany their movement adhere to these regulations:
Emergency movements: Escort vehicles 300 feet in front on 2 lane pavement and 300 feet in rear on dual lane or multilane undivided pavement must display adequate clearance lights at extreme edges of an overwidth load for night movements and oversize load signs shall be reflectorized or lighted. Escort vehicles will not be permitted to convoy movements.
Source of information: https://www.sos.mo.gov/cmsimages/adrules/csr/previous/7csr/7csr0400/7c10-2a.pdf