Such sign shall:
one to 42 Passengers = one emergency exit per side and one roof hatch
43 to 78 Passengers = two emergency exit per side and two roof hatches
79 and above Passengers = three emergency exits per side and two roof hatches
If floor insulation is required, it may be five-ply, at least e inch thick, or it shall equal or exceed properties of exterior type softwood plywood, C-D Grade, as specified in standard issued by the United States Department of Commerce. If plywood is used, all exposed edges shall be sealed.
Insulating material shall be placed at all contact points between the body and chassis frame on Type B, C and D buses, and shall be so attached to the chassis frame or body that it will not move under severe operating conditions.
Test panels to be prepared in accordance with Federal Specification TT-C 520b, paragraph 4.6.12 with modified procedure requiring that tests be made on a 48-hour air cured film at thickness recommended by compound manufacturer.
540 CMR, § 7.05