61-8-310. When local authorities may and shall alter limits. (1) If a local authority in its jurisdiction determines on the basis of an engineering and traffic investigation that the speed permitted under 61-8-303 and 61-8-309 through 61-8-313 is greater or less than is reasonable and safe under the conditions found to exist upon a highway or part of a highway, the local authority may set a reasonable and safe limit that:
     (a) decreases the limit at an intersection;
     (b) increases the limit within an urban district, but not to more than 65 miles an hour during the nighttime;
     (c) decreases the limit outside an urban district, but not to less than 35 miles an hour; or
     (d) decreases the limit in an area near a school, a senior citizen center, as defined in 23-5-112, or a designated crosswalk, as crosswalk is defined in 61-1-209, that is close to a school or a senior citizen center to not less than 80%, rounded down to the nearest whole number evenly divisible by 5, of the limit that would be set on the basis of an engineering and traffic investigation, but not less than 15 miles an hour. If warranted by an engineering and traffic investigation, a local authority may adopt variable speed limits to adapt to traffic conditions by time of day, provided that the variable limits comply with the provisions of 61-8-206.
     (2) A board of county commissioners may set limits, as provided in subsection (1)(c), without an engineering and traffic investigation on a county road, as defined in 60-1-103.
     (3) A local authority in its jurisdiction may determine the proper speed for all arterial streets and shall set a reasonable and safe limit on arterial streets that may be greater or less than the speed permitted under 61-8-303 for an urban district.
     (4) An altered limit established as authorized under this section is effective at all times or at other times determined by the authority when appropriate signs giving notice of the altered limit are erected upon the highway.
     (5) Except as provided in subsection (1)(d), the commission has exclusive jurisdiction to set special speed limits on all federal-aid highways or extensions of federal-aid highways in all municipalities or urban areas. The commission shall set these limits in accordance with 61-8-309.

     History: En. Sec. 43, Ch. 263, L. 1955; amd. Sec. 1, Ch. 89, L. 1971; amd. Sec. 57, Ch. 316, L. 1974; R.C.M. 1947, 32-2146; amd. Sec. 2, Ch. 614, L. 1985; amd. Sec. 1, Ch. 686, L. 1991; amd. Sec. 1, Ch. 213, L. 1993; amd. Sec. 3, Ch. 287, L. 1995; amd. Sec. 5, Ch. 43, L. 1999.