Access Category Compliance Requirements

The NMDOT State Access Management Manual identifies the following: ‘The level of access that is allowed along a state highway is dependent on the intended function of that highway. The function of a particular highway is defined in terms of service to through traffic movements (mobility) versus access to abutting properties (land accessibility).'

The level of access that is allowed along a state highway is dependent on the intended function of that highway. The function of a particular highway is defined in terms of service to through traffic movements (mobility) versus access to abutting properties (land accessibility).

 

The NMDOT has developed a classification system that is based on the intended function of each state highway. Based on this functional classification system, eight access categories are defined for the purpose of managing access along New Mexico’s highways. There are four urban access categories and four rural access categories. The access categories apply to highways functionally classified as collector roadways or above. The following is the access category requirements for rural minor arterials (RMA) from the NMDOT State Access Management Manual:

(1) Functional Description: The rural minor arterial system provides linkages between cities, larger towns and other traffic generators serving interstate, intrastate and intercounty travel needs.  Rural minor arterials provide for relatively high travel speeds and minimum interference to through movement.

(2) General Access Characteristics: Direct access service to abutting land is subordinate to providing service to through traffic movements.

(3) Performance: The operational performance of RMA facilities should meet LOS C standards at a minimum, with the exception of unsignalized access points which should meet LOS D standards. See Sub-Section  15.C, Table 15.C-1.

(4) Traffic Signal Spacing: The minimum spacing of signalized intersections varies by posted speed limit and is 1/3 mile for 30 mph or less, 1/2 mile for 35 to 50 mph, and 1 mile for 55 mph or more.  Preference is given to through traffic movement and progression bandwidths of 35 to 45 percent for two-way travel are required.  See Sub-Section 15.F, Table 15.F-1 .

(5) Spacing of Unsignalized Accesses - Full Access: The minimum spacing of full-access unsignalized intersections varies by posted speed limit and is 660 feet for 40 mph or less, 1,320 feet for 45 to 50 mph, and 2,640 feet for 55 mph or more. On highways with non-traversable medians, this represents the allowable spacing between median openings.  See Sub-Section 18.C, Table 18.C-1, and Sub-Section 18.D .

(6) Spacing of Unsignalized Access - Partial Access: The minimum spacing of unsignalized access points and driveways where some turn movements may be restricted, depending on the type of median control, varies by posted speed limit as follows (see Sub-Section 18.C, Table 18.C-1):

                • ≤ 30 mph:  200 feet

                • 35 to 40 mph:  325 feet

                • 45 to 50 mph:  450 feet

                • ≥ 55 mph:  725 feet

(7) Corner Clearance: When property is adjacent to an intersection, proposed access points on the approach or departure sides of the intersection should be controlled. Corner clearances should be consistent with the access spacing standards defined in Table 18.C-1 .

(8) Left-turn and Right-turn Acceleration Lanes: The need for left-turn and right-turn acceleration lanes is based on safety conditions associated with site-specific conditions. The Department may require acceleration lanes wherever safety concerns occur at a proposed access.

(9) Left-turn Deceleration Lanes: Left-turn deceleration lane requirements vary by posted speed and are based on the traffic volume on the highway and the number of left-turns expected at an access (see Sub-Section 17.B, Table 17.B-3 and Table 17.B-4). Left-turn deceleration lanes are required, regardless of the traffic volume on the highway, when the following left-turning volumes are expected:

 

                Posted Speed                     Two-lane Highway                            Multi-Lane Highway

                ≤ 30 mph                               26 left-turns per hour                           36 left-turns per hour

                35 to 40 mph                         21 left-turns per hour                           26 left-turns per hour

                45 to 55 mph                         16 left-turns per hour                           21 left-turns per hour

                > 55 mph                               11 left-turns per hour                           16 left-turns per hour 

(10) Right-turn Deceleration Lanes: Right-turn deceleration lane requirements vary by posted speed and are based on the traffic volume on the highway and the number of right-turns expected at an access (see Sub-Section 17.B, Table 17.B-5 and Table 17.B-6).  Right-turn deceleration lanes are required, regardless of the traffic volume on the highway, when the following right-turning volumes are expected:

                Posted Speed                     Two-lane Highway                            Multi-Lane Highway

                ≤ 30 mph                               31 right-turns per hour                        36 right-turns per hour

                35 to 40 mph                         31 right-turns per hour                        36 right-turns per hour

                45 to 55 mph                         26 right-turns per hour                        31 right-turns per hour

                > 55 mph                               21 right-turns per hour                        21 right-turns per hour 

(11) Other References to Sections of the State Access Management Manual 

                • Definitions of Terms: Section 7

                • Access Categories: Section 10

                • Permitting Process: Section 14

                • Traffic Study Requirements: Section 16

                • Design Specifications: Section 18

                • Access Control Review Procedures: Section 19