N.M. Admin. Code § 18.31.6.18 - ACCESS LOCATION AND DESIGN STANDARDS
The location and design of access points along state highway facilities shall be in accordance with standards established by the department. These standards are defined below and are expounded on in Section 18 of the state access management manual. Where specific design criteria are not provided in 18.31.6.18 NMAC, the design approach should be based on nationally accepted standards and shall be consistent with department specifications.
A.
General: The department has
developed these standards to provide guidance for the location and design of
access points along state highways, specifically for those highways in access
categories (provided in Section
18.31.6.10 NMAC). These criteria
are based upon established design standards meant to protect public safety, to
maintain safe and smooth-flowing traffic operations, and to preserve the
intended function of all state highway facilities.
(1) Local standards: Where a local
jurisdiction has established more stringent design standards than the
department, the local standards should be applied with the concurrence of the
department.
(2) Material placed
within state rights-of-way: Any materials used within state highway
right-of-way shall be subject to approval by the department. Refer to
18.31.6.14 NMAC for additional
requirements regarding construction within state highway
right-of-way.
B.
Access location: Access points should be located along state
highways to minimize turning movement conflicts between adjacent access
facilities, and to provide adequate separation of conflicts for oncoming
motorists. Stopping sight distance and intersection area of influence should be
considered in determining access point locations.
(1) Direct access: The number of access
points should be limited to one per site unless frontage is adequate and design
hour traffic volumes indicate that the operational level of service for a
single access is expected to be below the minimum acceptable LOS
standards.
(2) Proximity to
speed-change lanes: Any part of an access including radius returns shall not be
permitted within a speed-change lane, or within 50 feet of either the leading
or trailing limits of a speed-change lane.
(3) Interchange proximity: Access shall not
be permitted within the access control limits of an interchange, as established
by the department's access control determination, or within 50 feet of the
leading or trailing edge of the access control limits for the
interchange.
(4) Corner clearance:
Driveway access should be controlled on both the approach and departure sides
of an intersection to maintain adequate corner clearances.
(5) Edge clearance: The location of access
points relative to frontage property lines should be based on local
requirements. When property frontage is not adequate to comply with local
government's edge clearance requirements, shared access should be
considered.
C.
Access spacing:
(1)
Non-developed and developing areas: The spacing of access points in
non-developed and developing areas should be based on the access category, the
posted speed limit, and the type of access requested (i.e., intersection or
driveway). Desired access spacing standards are provided in Section 18 of the
state access management manual. An applicant may request a
variance to the spacing requirements when physical characteristics of a
property preclude the desired spacing.
(2) Developed areas/business districts: In
developed or redeveloping areas where existing driveway locations preclude
access spacing based on desired standards, new access points should be located
to minimize conflicts with existing access points. Access points should be
consolidated where possible to provide shared property access.
D.
Median openings:
New median openings on state highways with non-traversable medians should not
be allowed unless a traffic engineering evaluation analyzing all related
traffic and safety issues is prepared and approved by the department. Median
openings at intersections or full-access driveways should be spaced with a
minimum frequency based upon the access category and posted speed of the
highway.
E.
Selection of
design vehicle: The design vehicle should be used to determine the
geometric characteristics of a roadside access or median opening, and to define
the required design components for the adjacent highway. This vehicle should be
the largest vehicle that is expected to access the site on a daily basis.
Selection of the design vehicle is subject to the approval of the district
traffic engineer.
F.
Sight
distance: Sight distance at all access locations shall be adequate to
provide safe operating conditions for the motoring public. An access permit
should not be issued unless adequate stopping sight distances are provided for
motorists passing the access, and adequate entering and crossing sight
distances are provided for motorists using the access. The permittee shall
maintain adequate, unobstructed sight distance in both directions from the
access. Any potentially obstructing objects such as but not limited to
advertising signs, structures, trees and bushes, shall be designed, placed and
maintained at a height not to interfere with the sight distances needed by any
vehicle using the access. Roadway reconstruction may be required to provide
adequate sight distance.
G.
Access horizontal alignment: The access centerline should be
perpendicular to the state highway centerline and extend tangentially for a
minimum distance of 40 feet beyond the near-side edge line. An acute angle
between 75 degrees and 90 degrees may be permitted if significant physical
constraints exist. Acute angles less than 75 degrees shall require special
approval of the department.
H.
Access radius: The access radius should be designed to accommodate
the design vehicle expected to use the access on a daily basis. Access radii
apply to driveways that are not urban section driveway cuts.
I.
Driveway width: The width of
a driveway should be measured exclusive of radii or tapers. Driveway widths
should vary by design vehicle. All two-way driveways should accommodate a
concurrent entering and exiting design vehicle, including the design vehicle's
off-tracking.
J.
Access
connection depth: The access connection depth should be designed to
facilitate the movement of vehicles off the highway to prevent the queuing of
vehicles on the traveled way. An access shall not be approved for parking areas
that require backing maneuvers within state highway right-of-way. All
off-street parking areas must include on-site maneuvering areas and aisles to
permit vehicles to enter and exit the site in forward drive without
hesitation.
K.
Speed change
lanes: Design specifications for speed change lanes are provided in
Section 18 of the state access management manual. Schematic
illustrations of speed-change lanes are included in the appendix of the
state access management manual.
(1) Deceleration lanes: Deceleration lanes
typically consist of three components: transition taper, deceleration distance,
and queue storage. The length of the lane should allow a vehicle to come to a
comfortable stop prior to reaching the end of the expected queue in the
lane.
(2) Acceleration lanes:
Acceleration lanes should consist of a full-width lane and a transition taper.
Acceleration lanes should be designed so that a turning vehicle will reach a
speed between seventy-five and eighty percent of the highway posted speed at
the point where the full-width lane ends and the transition taper
begins.
(3) Shoulders: Where
shoulders are present along a roadway and speed change lanes are required, the
shoulders should be continued along the speed change lanes. A minimum shoulder
width of four feet should be provided adjacent to speed change lanes.
(4) Bicycle lane width: When a right-turn
deceleration lane or acceleration lane is required on a roadway with designated
bicycle lanes, a five foot lane width (seven foot desirable) should be provided
between the outside travel lane and the speed-change lane.
(5) Grade adjustment: Adjustments should be
made to the speed change lane lengths based on the roadway grade.
(6) Truck design: If a speed-change lane is
designed for a site with five or more large trucks during the design hour, a
combination truck design vehicle should be used as the design
vehicle.
(7) Pavement: The speed
change lane pavement section should be full depth and match the pavement
section design of the adjacent roadway. All pavement designs require approval
by the department.
L.
Median design for turn lane installation: Medians should be
designed to accommodate the largest design vehicle anticipated to use the
access, and may provide either partial or full access to a site. Where a single
left-turn lane is necessary along a state highway, a minimum median width of 16
feet should be provided. Positive channelization should be provided for all
median openings. Median paving should be full depth and match the pavement
section design of the existing roadway. The installation of a median opening
should not reduce the conveyance or storage capacity of the median, pertinent
to its drainage function within the highway section.
M.
Setbacks: Improvements on
public or private property adjacent to the right-of-way should be located so
that parking, stopping, and maneuvering of vehicles within the highway
right-of-way will not occur.
N.
Access vertical alignment: The vertical alignment of all access
locations should be designed to minimize vehicle bounce and prevent
high-centering of vehicles with a maximum clearance of four inches. The maximum
grade for a driveway should be ten percent for a low volume residential
driveway and eight percent for all other access locations. Steeper access
drives require special department approval. A level area (maximum two percent
grade) 20 feet in length should be provided at each access to ensure proper
sight distance from the access.
O.
Roadside safety: Careful consideration shall be given to the
roadside clear zone. The permittee shall provide adequate clear zones. The
roadside clear zone should be designed per the AASHTO roadside design
guide and applicable department standards.
P.
Non-motorized considerations:
Access designs should provide for the safe movement of all right-of-way users,
including but not limited to pedestrians, bicyclists, equestrian and the
handicapped. Where non-motorized facilities cross an access point, such as
bicycle trails, appropriate modifications should be made to maintain safe
operations for both facilities.
(1)
Sidewalks: Sidewalks should be constructed along urban arterial and collector
state highways. Sidewalks are required where they exist on adjacent properties
to maintain consistency along the highway facility. Sidewalk widths should
match existing adjacent sidewalk widths, but in any case shall conform to all
federal, state, and local regulations and ordinances.
(2) Bicycle facilities: Bicycle facilities
along urban arterials and collectors should be constructed in accordance with
the AASHTO guide for the development of bicycle facilities.
Bicycle facilities should only be signed where designated by the state or local
jurisdiction, with approval of the department.
(3) ADA: Non-motorized facilities shall be
designed in accordance with the Americans with Disabilities Act and applicable
department standards. Curb ramps shall be provided on urban sections where
sidewalk and curb returns exist.
Q.
Lighting: Where lighting is
required at an access point, the lighting design shall comply with Department
and AASHTO standards and the Night Sky Protection Act (Sections
74-12-1 NMSA 1978 through 74-12-11
NMSA 1978). The lighting design shall use full cut-off fixtures, and be
consistent with AD 226, roadway lighting.
(1)
Signalized access: Illumination shall be provided at all signalized
intersections in accordance with AASHTO's an informational guide to
roadway lighting or as otherwise approved by the department.
(2) Site illumination: Light beams from
on-site lighting systems shall not be directed toward oncoming traffic along
the adjacent roadway(s). All site illumination shall be constructed outside of
the state highway right-of-way and outside of the roadside clear
zone.
R.
Drainage: Adequate drainage within state highway right-of-way
shall be maintained at all access locations. Drainage of roadside ditches shall
not be altered or impeded, and the applicant shall provide suitable and
approved drainage structures as required by the department. All site drainage
shall be collected prior to entering state highway right-of-way. Site drainage
shall not be permitted to drain into state right-of-way without written
approval of the department. Drainage mitigation design shall be in accordance
with administrative memorandum 221, drainage design criteria, and the
department drainage manual. Access permit applicants shall submit drainage
analysis documentation to the department prior to changing site drainage
conditions.
S.
Right-of-way
fencing: Driveways shall not be permitted through an existing
right-of-way fence, the continuation of which is necessary for the safety of
the traveling public, unless the applicant first agrees in writing to construct
and maintain a gate or a cattle guard and additional fence in good repair and
to keep the gate closed to livestock. The department shall determine whether a
gate or cattle guard is required. All new fencing along a state highway shall
be constructed so that clear sight triangles are provided for ingressing or
egressing vehicles. This may require an offset from the right-of-way line to
meet the minimum clear site triangles, on a case by case basis.
T.
Mailboxes: Mailboxes
installed within the state highway right-of-way shall be constructed in
conformance with the rules and regulations of the U.S. Postal service and the
design standards of the department. AASHTO's a guide for erecting
mailboxes on highways, should also be used for the location and design
of mailbox installations.
U.
Utilities: All utilities located within the state highway right-of-way
shall comply with the department's utility accommodations Policy and 17.4.2.
NMAC.
V.
Environmental
review: As may be required by law.
Notes
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