(A) Generally.
(1) A State Professional Engineer must sign and seal all roadway construction plans and revisions submitted for city review. A P.L.S. or P.E. may certify as-built drawings verifying that the construction was completed according to plans. Street designs shall be consistent with the NCDOT Subdivision Roads Minimum Construction Standards, except as modified herein or as directed by the city.
(2) (a) Curb and gutter is required for all new street construction but may be waived at the discretion of the City Engineer, and roadside ditches or combination thereof used for storm water quality and conveyance.
(b) Five-foot wide sidewalks are required on each side of the street and around cul-de-sacs. Handicap ramps are required wherever sidewalks intersect curb and gutter.
(3) (a) Thoroughfare streets provide for movement of high volumes of traffic throughout the city. In general, thoroughfare streets consist of numbered state roads and other major streets as described in the NCDOT, County or City Thoroughfare Plan. Design criteria for thoroughfare streets shall be on a case-by-case basis. Direct driveway access onto thoroughfares is prohibited.
(b) Commercial streets provide direct access to commercial property and may be served by either thoroughfare or collector streets. Design shall be on a case-by-case basis.
(c) Collector streets connect the residential and commercial streets to thoroughfare streets, and may supplement the thoroughfare system by providing a limited amount of through traffic. Collector streets are required when serving more than 150 residential units, when connecting adjoining residential areas or as determined necessary by the City Engineer.
(d) Residential streets provide a dual service of lot access and traffic movement between local residential streets and collector streets.
(e) Private streets may be used within commercial and multi-family developments. Design requirements will vary depending on utility and vehicular traffic needs and should be sufficient for service and emergency vehicles. Private streets within subdivided single-family developments are generally prohibited. Private streets shall be designed to public street standards or as otherwise directed by the City Engineer.
(4) Retaining walls are not allowed in the right-of-way. Retaining walls are also not allowed to hold up roadway fill. Any proposed retaining walls must be beyond the theoretical two-to-one slope from the right-of-way line.
(5) All sewer mains and storm drains shall be located within the paved street area. Sewer shall be located in the center of the street; storm drainage shall be located under the curb line. Water mains shall be located four feet back of curb.
(6) Streets that are multi-lane and/or divided will require special design reviews.
(7) For stub out streets, roads shall be built to the property line. Temporary hammerhead turnarounds are required for stub out streets over 200 feet long.
(8) All privately owned common open space shall be accessible for maintenance purposes.
(9) Cleared and graded areas beyond the end of public streets shall be barricaded with guardrail or gates to prevent vehicular access. Barrier details shall be provided on the construction drawings.
(10) Street trees shall be planted along both sides of the street on 40-ft c-c. The trees shall be a minimum of three-inch caliper, and the preferred tree species are those recommended by the Urban Forestry Administration’s Recommended Street Tree List, latest version.
(11) (a) Any person constructing, reconstructing or altering a residential or non-residential driveway and all other infrastructure improvements within the city right-of-way, including, but not limited to, drainage pipes, sidewalks, curbs or driveways shall apply for and receive a driveway and right-of-way permit prior to work commencing.
(b) Any street or driveway access onto a NCDOT owned roadway shall be permitted in accordance with NCDOT standards, criteria and requirements.
1. The standard application, design plans and associated permit fees must be submitted in its entirety and in duplicate to the office of the City Engineer for review and approval. (Note: Refer to the City of Mount Holly Land Development Guidelines for the application form.)
2. Any person who receives a driveway and right-of-way permit shall be responsible for repairing damage to the public infrastructure resulting from the work permitted under this chapter.
3. The City Engineer shall review the driveway and right-of-way design plans and shall issue the permit unless he or she finds the driveway, if constructed as proposed, will substantially interfere with or pose a danger to the following:
a. Persons using the street or sidewalk intersected by the driveway;
b. Public facilities (including utility poles, traffic signal standards and the like);
c. Fail to comply with the specifications of the city or any of the provisions of this chapter; and/or
d. The overall drainage pattern or flow of runoff within the storm drainage system.
(B) Street design.
(1) The following general street layout guidelines shall be used in designing subdivision projects:
(a) Shorten street segments where possible;
(b) Realign streets to eliminate through connections to arterial roads;
(c) Orient cul-de-sac openings toward pedestrian destinations;
(d) Provide traffic calming devices on residential collector roads;
(e) Promote lower speeds through horizontal and vertical design approaches; and
(f) Provide connectivity to adjacent undeveloped properties as needed.
(2) Cul-de-sacs shall have a minimum 35-foot roadway radius to the edge of pavement and a minimum 50-foot right-of-way radius. A maximum length of a cul-de-sac is 1,000 feet.
(3) The street typical section shall be as per the city standard details.
(4) Normal crown cross-slope for collector streets shall be one-quarter inch per foot and for residential streets, one-quarter inch per foot.
(5) Cut and fill slopes steeper than two-to-one are not allowed.
(6) The maximum design speed is 25 mph on residential collector/non-residential streets. The maximum design speed is 25 mph on residential streets. For streets with design speeds greater than 30 mph, a design waiver will be required. Design standards will follow AASHTO requirements.
(7) The minimum centerline radius for residential collector/non-residential streets is 150 feet. The minimum centerline radius for residential streets is 100 feet. For design speeds greater than 30 mph, the minimum centerline radius is to be determined according to AASHTO. Super-elevation will be permitted as approved by the city. Minimum tangent length between horizontal curves shall be 50 feet for residential streets, and 100 feet for collector streets.
(8) The minimum rate of vertical curvature (“K” value) for residential collector/non-residential streets shall be 30 for sag and 30 for crest (minimum sight distance of 300 feet). The minimum rate of vertical curvature (“K” value) for residential streets shall be 20 for sag and 20 for crest (minimum sight distance of 200 feet).
(9) Maximum grade allowable for residential collector/non-residential streets is 8%. Maximum 10% grade for residential streets.
(10) Minimum grade of 1% shall be maintained for all curb and gutter streets and a minimum grade of 2% for roadside ditches.
Design Values
| ||||||
K Sag | K Crest | (Feet) Minimum Radius | (Feet) Minimum Sight Distance | (%) Maximum Grade | (%) Minimum Grade | |
Collector | 30 | 30 | 150 | 300 | 8 | 1 |
Residential | 20 | 20 | 100 | 200 | 10 | 1 |
(11) Grades should not exceed 3% for the first 150 feet from the centerline of any publicly maintained road for a residential collector/non-residential street. Grades should not exceed 5% for the first 100 feet from the centerline of any publicly maintained road for a residential street.
(12) Intersections shall intersect at 90 degrees unless approved by the City Engineer.
(13) Turn lanes shall have a minimum width of 11 feet and be incorporated when required by traffic considerations. Tapers shall be designed to meet NCDOT design speed criteria and the city’s recommendations.
(14) Plans for all widenings shall show that the contractor will saw and remove the top one and one-half inches of existing pavement a minimum of 12 inches from the existing edge of pavement, or as directed by the city, and place new pavement over the existing base. If widening is to occur on both sides of the street, the entire street cross-section shall be overlaid with one inch of asphalt SF 9.5A. Appropriate traffic control plans shall be submitted for all widenings or other work adjacent to existing roadways. All pavement marking shall be completed by the developer using thermoplastic paint and shall be shown on the construction drawings.
(15) Curb turnout radius shall be 25 feet on city streets and 30 feet when intersecting NCDOT streets.
(16) Guardrail shall be installed as determined by AASHTO.
(17) Offset intersections shall be avoided; however, when necessary, a minimum distance of 125 feet between centerlines shall be provided.
(18) Sight triangles 35 feet by 35 feet shall be preserved for all intersections. Additional sight triangles of ten feet by 70 feet shall be provided for access onto thoroughfare, commercial and NCDOT streets. Sight triangles shall be shown on preliminary and final plats, and shall be shown on the overall site drawings.
(C) Street lighting.
(1) The developer shall be required to install decorative street lighting on all streets. All lighting shall be installed prior to final acceptance by the city. The city shall not be responsible for maintenance and repair of decorative street lighting. Maintenance and repair of decorative lighting shall be the responsibility of the utility provider, or the homeowner or property owners’ association.
(2) The developer shall consult with the appropriate utility provider in the development of proposed street lighting plans. Lighting plans shall be submitted to the Planning and Development Department for approval prior to installation of lighting. All poles shall be of metal construction. Wooden poles are not allowed. In the interest of cost savings, the city reserves the right to require the most energy efficient style lighting as part of the lighting plan submitted such as, but not limited to, light-emitting diode (LED).
(3) Street lights shall be located at all intersections, and at the end of all cul-de-sacs and turnarounds. Street lights that are not located at intersections shall be located on or adjacent to property corners.
(D) Street signage.
(1) The developer shall be responsible for installation of speed limit signs, stop signs, street name signs and other signage throughout the development as determined necessary by the city. The developer shall submit a signage plan to the city for approval prior to installation of street signs. Sign installation shall be complete prior to final acceptance by the city.
(2) Street name signs shall match current city standards and shall be approved by the city prior to installation. Other signage shall comply with NCDOT and Manual on Uniform Traffic Control Devices (MUTCD) standards. All sign materials and installation shall comply with the standard details, city, NCDOT and MUTCD standards.
(3) Street sign poles shall be decorative to match decorative street light poles. The city will not be responsible for maintenance and repair of decorative street sign poles. Maintenance and repair shall be the responsibility of the homeowner or property owners’ association. Other signage, such as speed limit signs, may be on decorative posts, or on galvanized posts as shown in the NCDOT standards. The city will not be responsible for the maintenance of any decorative street posts.
(4) Street signs shall include the city logo of the “M” in accordance with the city branding campaign.
(E) Street specifications. Street construction materials shall be in accordance with the most current edition of the NCDOT Standard Specifications for Roads and Structures, and Roadway Standard Drawings, as revised July 2012 (and as subsequently amended), except where standards in these guidelines are more stringent, or as directed by the city.
(F) Construction.
(1) All backfill shall be compacted to 95% of standard proctor density (AASHTO-T99), except the last 12 inches of subgrade, which shall be compacted to 100%.
(2) Proofrolling of subgrade and stone base shall be performed in the presence of the City Inspector using an over-loaded (on-site) triaxle dump with 22 to 25 tons of stone, third axle lifted. If rain occurs before placing stone on subgrade that has been proofrolled, or if rain occurs prior to placing asphalt on stone base that has been proofrolled, the subgrade and stone base must be proofrolled again as directed by the city.
(3) Subgrade must be checked by the City Inspector for grade elevation prior to placing stone base. Subgrade must meet all NCDOT and city requirements. Subgrade elevation must be within plus or minus one-half inch of the established grade in accordance with NCDOT standards after the subgrade has been graded to a uniform surface and rolled with a pneumatic roller.
(4) Stone base must meet all NCDOT and city requirements. Stone base elevation must be within plus or minus one-half inch of the established grade in accordance with NCDOT standards after the stone has been conditioned and compacted.
(5) All equipment to be used for asphalt compaction and asphalt placement must meet NCDOT requirements and be approved by the city prior to paving.
(6) (a) For all residential streets, the final one and one-half inch of pavement is not to be placed until after 80% of the homes have been closed in each specific phase.
(b) Asphalt shall be temporarily ramped around structures to prevent damage prior to final paving. The temporary asphalt shall be removed just prior to the final paving. The street shall be inspected by the city prior to the final paving. Any cracked, settled or other damaged pavement sections shall be repaired prior to final paving.
(c) The final one and one-half inch of paving is not to be placed for streets that will be used to access future phases of the development.
(7) Core samples shall be taken in locations determined by the City Inspector. The samples shall be taken by approved testing firms and the results for thickness and asphalt mix shall be provided to the city.
(8) All driveway entrances must meet State Department of Transportation and city requirements. Concrete driveway aprons are required for commercial entrances unless approved otherwise.
(9) Curb and gutter contraction joints shall be spaced ten feet on center for hand-formed curb and 15 feet on center for machined curb. Contraction joints shall be one-quarter inch wide by two inches deep. Joints shall be saw cut. Tooled joints may be approved by the city on a case-by-case basis if the contractor demonstrates that the joints can be neatly formed. Curb and gutter with two or more hairline cracks between joints shall be removed. Any curb that is completely cracked and separated shall be removed and replaced.
(10) All work must carry a one-year warranty from the date of City Council action for final acceptance on materials and workmanship, including damages from settlement. The city will not maintain any newly installed infrastructure until final acceptance of the project is granted by City Council. The one-year warranty period will not begin until final acceptance. The developer may not request final acceptance until all deficiencies have been satisfactorily addressed as determined by the city and a set of as-built drawings certified by the engineer of record have been submitted, reviewed and accepted by the city. It shall be the responsibility of the developer to request the final acceptance.
(11) Construction standards shall meet State Department of Transportation Standard Specifications for Roads and Structures, and Roadway Standard Drawings as revised July 2012 (and as subsequently amended), except where standards in these guidelines are more stringent, or as directed by the city.
(12) The developer or owner is responsible for the quality of each infrastructure element that will ultimately be turned over to the city for maintenance. The developer or owner is expected to inspect the work of their contractors and schedule testing as needed to ensure compliance with these guidelines. The city will not accept for maintenance infrastructure improperly constructed and/or of quality less than industry standards. It is imperative for the developer or owner to inform the city of any problems that cause deviations from the approved design plans. The city acts as an observer during construction. The city must be provided with sufficient information and documentation to support the quality of construction and compliance with the approved design plans.
(Ord. passed 9-27-2021) Penalty, see § 153.999