| (a) General.
(1) Encasement.
Attached Graphic
(A) Underground utility facilities crossing the highway
shall be encased as shown in Figure §21.40(a)(1). The encasement
must be a single structure with no open seams. If used, polyvinyl
chloride (PVC) and high-density polyethylene (HDPE) pipe shall be
glued with an appropriate adhesive, bonded, or mechanically fastened.
Steel pipe shall be welded or bolted.
(B) The encasement may be of metallic or non-metallic
material, depending on the type of utility facility. If the encasement
is not schedule 40 polyvinyl chloride (PVC) pipe, high-density polyethylene
(HDPE), or made of steel, the utility must demonstrate that the encasement
is adequate for the expected loads and stresses.
(C) The length of any encasement shall extend, as applicable,
to within five feet of the right of way, two feet of a connecting
longitudinal line, or five feet beyond the face of the curb, whichever
is greatest. These lengths of encasement include areas under center
medians and outer separations. At a district's discretion, the district
may waive the encasement requirement under center medians or under
outer separations that are more than 76 feet wide. At a district's
discretion and after considering traffic volume, condition of highway,
maintenance responsibility, and district practice, the district may
waive the encasement requirement under side road entrances.
(D) Unless waived by the district, an encasement is
required for installation under other department structures, such
as retaining walls, headwalls, and sound walls.
(2) Depth.
(A) Underground utility facilities shall be installed
at the applicable minimum depth of cover shown in Figure §21.40(a)(2)(A)
unless the district requires or authorizes a different depth under
this paragraph.
Attached Graphic
(B) The district may require a greater depth at specific
areas due to site conditions including areas such as culvert crossings,
drainage areas, and future project considerations.
(C) The district may require a greater depth based
on distance from edge of pavement.
(D) Where placements at the depths in this section
are impractical or where unusual conditions exist, the department
may allow installations at a lesser depth, but will require other
means of protection, including encasement or the placement of a reinforced
concrete slab. Reinforced concrete slabs or caps shall meet the following
standards:
(i) width -- five feet, or three times the diameter
of the pipe, whichever is greater;
(ii) thickness -- a minimum of six inches;
(iii) reinforcement -- #4 bars at 12 inch centers each
way or equivalent reinforcement; and
(iv) cover -- no less than six inches of sand or equivalent
cushion between the bottom of the slab/cap and the top of the pipe.
(3) Manholes.
(A) Manholes may not be installed unless necessary
for installation and maintenance of underground lines. In no case
shall a manhole be placed or permitted to remain in the pavement or
shoulder of a highway. However, on noncontrolled access highways in
urban areas, the district may, in its discretion, allow existing lines
to remain in place under existing or proposed highways. In these cases,
manholes may remain in place or be installed under traffic lanes of
low volume highways in municipalities only if measures are taken to
minimize the installations and to avoid locating them at intersections
or in wheel paths.
(B) To conserve space, a manhole's dimensions must
be the minimum acceptable by appropriate engineering and safety standards.
The only equipment that may be installed in manholes located on the
right of way is equipment that is essential to the normal flow of
the utility facility, such as circuit reclosers, cable splices, relays,
valves, and regulators. Other equipment, such as substation equipment,
large transformers, and pumps, shall be located outside the right
of way.
(C) Inline manholes are the only type permitted within
the right of way. The width dimensions may not be larger than necessary
to hold equipment involved and to meet safety standards for maintenance
personnel. Outside width, the dimension of the manhole perpendicular
to the highway, may not exceed ten feet, with the length to be held
to a reasonable minimum. The outside diameter of the manhole chimney
at the ground level may not exceed 36 inches, except that if the utility
demonstrates necessity, the district may, at its discretion, allow
an outside diameter of up to 52 inches. The top of the roof of the
manhole must be five feet or more below ground level.
(D) All manhole covers shall be installed flush with
the ground or pavement structure. In order to minimize vandalism,
manhole covers must weigh at least 175 pounds. Manhole rings and covers
must be designed for HS-20 loading.
(E) Manholes shall be straight, inline installations
with a minimum overall width necessary to operate and maintain the
enclosed equipment. The utility is responsible for any adjustment
of the manhole rim that may be needed to meet grade changes.
(4) Installation.
(A) A department permit is required for all installation
of utility facilities in the department's right of way.
(B) If the installation of the utility facility deviates
from the approved location, the district, at its sole discretion,
may require the adjustment of the utility facility to the approved
location.
(C) Utility facilities placed beneath any existing
highway shall be installed by boring or tunneling. Jacking may not
be used unless approved in writing by the district. The use of explosives
is prohibited. Pipe bursting or fluid/mist jetting may not be used
unless approved in writing by the department. Longitudinal installation
of a utility facility across driveways and intersecting roadways shall
be bored. Open trench construction through intersecting roadways and
driveways may not be used unless approved in writing by the district
engineer.
(D) To preserve and protect trees, shrubbery, and other
aesthetic features within the department's right of way, the district
may specify the extent and methods of tree removal, tree trimming,
or the replacement of the aesthetic features. Landscape areas in the
department's right of way that are associated with residences shall
be bored, unless the district approves another method. The district
may require boring on steep slopes where vegetation may be damaged.
(E) For rural, uncurbed highway crossings, all borings
shall extend beneath all travel lanes. Unless precluded by right of
way limitations, the following clearances are required for rural highway
crossings:
(i) 30 feet from all freeway mainlanes and other high-speed
(exceeding 40 mph) highways except as indicated in clauses (ii) -
(iv) of this subparagraph;
(ii) 16 feet for high-speed highways with current average
daily traffic volumes of 750 vehicles per day or fewer;
(iii) 16 feet for ramps; or
(iv) ten feet for low-speed (40 mph or less) highways.
(F) The reamed bore size may not exceed 40 percent
of the outside diameter of the encasement, and a reamer that allows
the natural wet grout to remain shall be used. Alternately, annular
voids greater than one inch between the bore hole and the carrier
line or encasement], if used, shall be filled with a slurry grout
or other flowable fill acceptable to the department to prevent settlement
of the highway facility.
(G) Unless an open-trench installation is approved
by the district in locations where adequate space is not available,
all borings for curbed highway crossings shall extend beneath travel
and parking lanes and beyond the back of curb and sidewalk, plus:
(i) 30 feet from facilities with speed limits of 40
mph or greater; or
(ii) five feet from highway facilities with speed
limits of less than 40 mph or less.
(H) Where circumstances necessitate the excavation
of a bore pit or the presence of directional boring equipment closer
than 30 feet from the edge of pavement, approved protective devices
shall be installed for protection of the traveling public in accordance
with §21.38 of this subchapter (relating to Construction and
Maintenance). Bore pits shall be located and constructed in such a
manner as not to interfere with the highway structure or traffic operations.
Shoring shall be utilized for the protection of the highway facility,
and its use and design must be approved by the district.
(I) All traffic control devices, including signs, markings,
or barricades used to warn motorists and pedestrians of the construction
activity must conform to the TMUTCD.
Cont'd... |
