(A) The speed zone ahead sign (R2-5c), together with a corresponding regulatory speed plate (R2-I101), shall be erected in advance of any speed zone that is ten mph or more under the limit in a preceding statutory limit.
(B) (1) The speed zone ahead sign shall be placed approximately 500 to 600 feet in advance of all altered speed zones in accordance with § 2 B-14 of the MUTCD and shall always be followed by a basic speed limit sign (R2-1) erected at the beginning of the zone where the altered speed limit applies.
(2) On divided and one-way facilities having two or more lanes in one direction, signs shall be posted on both sides of the highway for all signs described above.
(3) Additional speed limit signs as described in division (D) below, in the same zone need not be posted on both sides of the road.
(C) The difference in the speed limit from one altered speed zone to an adjacent altered speed zone shall not be more than ten mph.
(D) Speed limit signs for altered zone shall be erected:
(1) At the beginning of each zone where the speed limit is altered;
(2) At the point of change from one zone to another; and
(3) At additional locations within the zone where it is necessary to remind the motorist of the limit that applicable.
(E) Signs shall not be erected until the speed limits are approved and are officially authorized.
(F) The distance between basic speed limit sign installations in altered speed zones should be as follows:
Speed Limit (mph) | Minimum Distance | Maximum Distance |
30 or less | 660 feet or 2 blocks | 1,320 feet or 4 blocks |
35 or 40 | 990 feet or 3 blocks | 1,980 feet or 6 blocks |
45 or 50 | 1,320 feet or 4 blocks | 2,640 feet or 8 blocks |
(G) The recommended distances between speed signs do not apply to the posting of statutory limits.
(H) The size of speed limit signs shall conform with Table A, Size Designation in the Illinois Supplement to the national MUTCD. The size of the speed zone ahead and the first speed limit sign should be based on the speed limit preceding the zone. The size of the remaining signs is based on the speed in the zone.
(Res. passed 3-13-2007)