A. General: Guardrails are installed to reduce the occurrence of accidents by delineating the roadbed, to reduce accident severity by deflecting vehicles into safer paths, and to reduce the rate of deceleration in case of impending collisions with fixed objects.
B. Design And Placement: Only NMDOT approved guardrails shall be used. The length of guardrail should be planned in multiples of 12.5 feet. No abrupt or projecting ends shall face toward approaching traffic and delineators shall be installed according to the current edition of the New Mexico department of transportation "Standard Specifications For Road And Bridge Construction". Ordinarily, guardrail is placed only on the outside of curves.
1. Curbs: When guardrail is used in conjunction with roadside curbs, the face of the guardrail shall be flush with the face of the curb regardless of shoulder width. This is to prevent the takeoff ramp effect that may overturn a vehicle. When no curb is present, the face of the guardrail shall be flush with the edge of the shoulder.
2. Curves: On curves requiring a reduction in approach speeds, any one of the following conditions suggests installation of guardrail on the outside of the curves is needed:
a. Height of embankment is more than ten feet (10').
b. Side slopes are steeper than four to one (4:1).
c. Shoulder or pavement widths are substandard.
d. Roadside hazards are present.
3. Accidents: Whether on curves or tangents, consideration should be given to the installation of guardrails if there is a history of roadway accidents or if unusually high embankments or steep terrain give motorists a feeling of insecurity.
4. Low Visibility: In areas subject to low visibility or snow and ice conditions, or where traffic speed and volumes are high, guardrail may be needed where its installation would otherwise be questionable under less adverse conditions.
5. Other Conditions Requiring Guardrails: Guardrails may be required under the following conditions:
a. An obstruction or sudden constriction in roadway.
b. An isolated sharp curve on a roadway otherwise built to higher standards.
c. Approaches to bridge piers, abutments, trees or other obstructions.
C. Provisions For Snow Storage: When guardrails are considered for installation, especially for extended lengths, provision shall be made for adequate snow storage and removal. (Ord. 2007-06, 8-14-2007)