(A) Principles and philosophy.
(1) Design philosophy. Streets are the links that provide the basis for safe, efficient and economical access to commercial, industrial and residential areas. Safe residential streets are attained by specifying street geometries that discourage excessive speed and emphasize access. Residential streets should therefore promote:
(a) Safe and efficient movement of vehicular and pedestrian traffic; and
(b) Cost-effectiveness, that takes into consideration both initial construction and future maintenance costs.
(2) Principles. Streets and roads shall be designed to:
(a) Provide safe, smooth and efficient vehicular flow;
(b) Provide acceptable sight distance visibility;
(c) Provide good roadway foundation and subgrade drainage;
(d) Provide acceptable environmental features;
(e) Provide space for utilities, if necessary;
(f) Provide drainage for adjacent properties, when practical;
(g) Consider a community or subdivision master plan;
(h) Follow natural contours and preserve natural features;
(i) Minimize traffic speed, volume and congestion; and
(j) Minimize the amount of paved area as a means of reducing stormwater runoff.
(B) Street and road classifications.
(1) Parkways. Parkways are divided arterial streets with full or partial access, usually located within a ribbon of park-like development.
(2) Arterial street. Arterial streets function to conduct traffic between communities and activity centers, and to connect communities to major state and interstate highways. Arterials are primary roads characterized by high traffic volumes and high speeds.
(3) Collector street. Collector streets (in the town) serve as the principal traffic arteries within residential and commercial areas. Collector streets carry relatively high traffic volumes from arterial streets to lower classification streets.
(a) Subcollector streets provide passage to access streets and convey traffic to collector streets. Subcollectors provide access to residential lots and also carry some through traffic to lower classification streets.
(b) Subcollector streets may provide access to 25 to 100 dwelling units (lots).
(5) Access street. Access streets are designed to conduct traffic to up to 25 dwelling units and subcollector streets.
(C) Urban/suburban street standards. Urban/suburban streets are those streets near and around municipalities, shopping areas and commercial areas. Urban/suburban streets shall be subject to the following standards:
(D) Rural road standards. Rural roads are located in low-density areas away from commercial shopping areas. Rural roads are more informal and should blend into the surrounding landscape. Rural access roads usually carry less traffic than urban streets and may have a surface constructed of rock, pavement or an alternative surface approved by the Public Works Director. Earth roads may be allowed for cul-de-sacs with a length of 1,500 feet or less. Additionally, earth roads may be allowed within open space developments if: adequate drainage can be provided; soil conditions can accommodate the weight of a pumper truck; and a maintenance bond is provided to ensure continuing maintenance of the road.
(E) Centerline radius of horizontal curves.
(1) Centerline radius for horizontal curves is dependent upon many factors including type and condition of roadway surface, horizontal and vertical sight distances, design speed and degree of curvature.
(2) The roadway designer is required to utilize appropriate design techniques as outlined in American Association of State Highway and Transportation Officials (AASHTO) design publications in the design of horizontal and vertical curvature of the town and/or county roads.
(F) Public maintenance of streets and roads. In order to be eligible for public maintenance, streets and roads must comply with the town and/or county’s standard specifications for road and drainage systems.
(1) Acceptable methods. The methods of roadway drainage shall be acceptable, as detailed in the town and/or county’s standard specifications for road and drainage systems:
(a) Roadside ditching; and
(b) Curb and gutter piped systems.
(2) Sheet flow. Sheet flow from roadways is acceptable only where drainage discharges directly into a certified wetland area (such as at a causeway). Where freshwater wetlands are considered, the applicant’s engineer must provide drainage calculations showing runoff impact.
(1) The town’s standard nonindustrial asphalt pavement section is minimum two inches hot plant mix asphaltic concrete with prime coat on minimum six-inch compacted stabilized aggregate base course on prepared subgrade, in accordance with County Transportation Commission standards. A prime coat is recommended where FABC will not be paved within two weeks. Geotechnical data shall be submitted to substantiate the design of all new arterial roads, collector roads and parkways.
(2) The town/county standard earth roadway is identical to a town/county standard paved road, except that on earth roadways, stabilizing material shall be mixed into existing soil material for a depth of six inches. Crown should be six inches. County/town inspectors will determine if the prepared subgrade material and earth road overlay soil are acceptable.
(3) The town/county standard rock roadway is also identical to a county standard paved road, except that on earth roadways, the subgrade is overlaid with a minimum six inches compacted depth of stabilized aggregate base course with a two-inch crusher run aggregate wearing course. Crown should be six inches. County/town inspectors will determine if the prepared subgrade material and the rock overlay are acceptable. Instead of conducting the inspection with county/town staff, the Public Works Director shall be authorized to require independent testing and inspections at the applicant’s expenses.
(4) As an acceptable alternative to the town/county standard subgrade/pavement section, the developer may have a qualified independent testing laboratory/engineer determine/sample/test representative soil materials and design a base and pavement section in accordance with American State Highway and Transportation standards and to supervise the construction. County/town inspectors will test the completed subgrade prior to placement of base material and be on-site to verify proper placement of base, paving and synthetic materials.
(5) Coring samples will be conducted by the Public Works Department on every newly constructed road to ensure compliance with the approved construction plans. The number of samples and the location of testing sites will be selected at random by the Public Works Department.
(I) Wetlands. It is the responsibility of the developer to locate and to protect any wetlands (saltwater and freshwater). No development impacting any wetland area can be approved by town without prior approval by appropriate wetlands protection agencies. It is recommended that the developer contact U.S. Army Corps of Engineers permit section and DHEC-OCRM for specific wetland regulation information.
(1) The developer shall arrange to install all necessary utilities (water, sanitary sewer, electricity, telephone, street lighting or cable TV) as part of the development, or appropriate space must be allocated for future installation.
(2) Placement of utilities under the roadway surface will be considered on a case-by-case basis by public works.
(3) Lawn sprinkler systems are acceptable only if the design and installation is authorized by encroachment permit by public works.
(K) Encroachments. Encroachments into existing road rights-of-way and/or drainage easement will be authorized if the following criteria are met:
(1) A permit authorizing the encroachment is acquired from the Public Works Department;
(2) The encroachment meets safety requirements;
(3) The encroachment does not prevent normal maintenance operations and the town/county is relieved of all damage liability resulting from maintenance;
(4) The encroachment will be properly maintained by the permittee; and
(5) The permittee agrees to temporarily or permanently relocate/remove the encroachment when requested by the Public Works Director, at no cost to the county and/or the town.
(L) Minimum offset of trees and shrubs from road pavement.
(1) Trees and shrubs shall be set back from street and road pavement in accordance with the following minimum requirements.
(2) Understory trees may be located two feet from the edge of pavement with the approval of the Planning Director and Public Works Director.
(1) All roads to be maintained by the town and/or county must first be constructed (or upgraded) to meet current standards of this chapter and the county’s standard specifications for road and drainage systems.
(2) Any subdivision required to meet the town and/or county standards, but intended to be maintained privately, must be designed to meet all current standards. With approval of the decision-making body, construction of a portion of the facilities, such as removal of trees, can be deferred until such time as the town and/or county is asked to maintain the facilities. In such situations, the developer is required to submit a maintenance plan showing specifically what work is to be accomplished, specific schedules, who is perform the work and how payment for the work will be made. The potential owners of the development, or portion of the development, must be made aware of those factors through Homeowner’s Association bylaws and/or deed restrictions. The town and/or county will not perform any maintenance services in such developments until the roadway and/or drainageways have been brought up to then-current town and/or county standards.
(Ord. 20-8, passed 12-7-2000)