N.M. Code R. § 19.2.20.10 – Road Construction Standards

A. Width. The preferred minimum standard for roads built on state trust lands is a fourteen (14) -foot width for single-lane roads and a twenty (20) -foot width for double-lane roads, provided that the local situation doesn't dictate that it be wider. The maximum allowable grade without an engineering design is ten percent (10%).
B. Drainage. Drainage control shall be ensured through the use of drainage dips, outsloping, insloping, natural rolling topography, ditch turnouts, or culverts. Spacing of dips, broad-based drainage dips, culverts and turnout ditches will depend on cross slope, road grade and soil type. Drainages will be constructed in such frequency necessary to prevent headcuts or other forms of accelerated erosion or damage on adjacent areas.
C. Culverts. Culvert pipes shall be used for cross drains on grades in excess of ten percent (10%) gradient and on all major drainages. Roadbed culverts shall be used to drain road ditches when drainage dips are not feasible. All culvert sizing must be in accordance with accepted engineering practices (i.e., Talbot chart, etc.). The minimum size culverts in any installation is eighteen (18) inches.
D. Road Surfacing:
(1) Surfacing (i.e. caliche, gravel, soil stabilizer, sand, cinders, etc.) shall be required on all roads built on state trust lands where all weather access is needed, if the natural soil does not have the bearing capacity for heavy vehicles in both wet and dry weather and if these materials are economically available.
(2) The roadbed should be reasonably smooth, free of ruts, chuckholes, rocks, slides, washboards, dust pockets, soft spots or other driving hazards or nuisances.
E. Cattleguards and Fencing. Cattleguards are required for all fence lines crossing roads built on state trust lands, unless a wire or metal gate is approved by the SLO LUS and surface lessee.
(1) All cattleguard grid designs and foundation designs shall meet AASTHO load rating H-20, although AASTHO U-80 is required where heavy loads exceeding H-20 loading are anticipated.
(2) All cattleguard grids shall meet or exceed the road width, but shall not be less than fourteen (14) feet wide.
(3) Approach ramps (if needed) shall not be less than fifty (50) feet on each side of cattle guards and shall provide smooth transitions.
(4) Gates shall be installed on one (1) side of cattleguards. Gate construction will conform to the specifics set out in 19.2.20.11 NMAC.
(5) Fencing, if required, is to be a four (4) strand barbwire fence with twelve (12) inch spacing between strands.
F. Vegetation. All vegetation removed from roadbeds as a result of construction shall be disposed of by the grantee or lessee, by a method approved by the SLO LUS. Road standards may be modified to meet local conditions. Suggested reference material for road construction and maintenance practices is "Reducing Erosion from Unpaved Rural Roads in New Mexico,"published by the New Mexico energy, minerals and natural resources department soil and water conservation bureau.
[12/31/99; 19.2.20.10 NMAC – Rn, 19 NMAC 2. SLO 20.10, 09/30/02]