36 C.F.R. § 1192.39 Destination and route signs.
Title 36 - Parks, Forests, and Public Property
(a) Where destination or route information is displayed on the exterior of a vehicle, each vehicle shall have illuminated signs on the front and boarding side of the vehicle. (b) Characters on signs required by paragraph (a) of this section shall have a width-to-height ratio between 3:5 and 1:1 and a stroke width-to-height ratio between 1:5 and 1:10, with a minimum character height (using an upper case “X”) of 1 inch for signs on the boarding side and a minimum character height of 2 inches for front “headsigns”, with “wide” spacing (generally, the space between letters shall be
Title 36: Parks, Forests, and Public Property
PART 1192—AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION VEHICLES
Subpart B—Buses, Vans and Systems
§ 1192.39 Destination and route signs.