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A. General Requirements.
1. The subdivider shall construct all roads and streets shown on the plat in accordance with the requirements of this Ordinance.
2. All roads created by a subdivision shall be shown on the plat as dedicated to public use. Private roads are prohibited.
3. The local township highway commissioner, County Engineer, or representative who will take responsibility for maintaining the facility after final acceptance shall be referred to as the “local jurisdictional agency.”
4. All roadway design requirements shall comply with the applicable sections of the Illinois Department of Transportation (IDOT) Bureau of Local Roads and Streets (BLRS) Manual and the IDOT Bureau of Design and Environment (BDE) Manual.
5. All road right-of-way construction shall be done in accordance with and the latest edition of the following State of Illinois specifications: “The Standard Specifications for Road and Bridge Construction” (referred to as the “Standard Specifications”), the “Supplemental Specifications and Recurring Special Provisions”, the “Manual on Uniform Traffic Control Devices for Streets and Highways”, the “Manual of Test Procedures for Materials”, the “Highway Standards” and the “Bureau of Design and Environment Special Provisions”. Further, the following Region 1 District 1 requirements shall apply: the “District One Special Provisions” and the “District One Details”.
B. General Roadway Design.
1. The maximum length for a block between intersecting roads is one thousand two hundred (1,200) feet.
2. The use of cul-de-sacs and eyebrow streets are prohibited, unless all of the following standards are met:
a. It is determined necessary by, and approval is received in writing from, the applicable township highway commissioner.
b. It avoids impacts to sensitive environmental resources as identified in the site inventory or it avoids street designs that allow cut through traffic between arterial streets.
3. Road access to adjacent properties and direct connection with existing abutting public road right-of-way in adjoining subdivisions is required, except in the following situations:
a. Written approval is received from the applicable township highway commissioner that such interconnection is not required.
b. Written approval is received from the County Engineer that such interconnection is not required, if the subdivision fronts or has access to a County highway.
c. It avoids impacts to sensitive environmental resources as identified in the site inventory or it avoids street designs that allow cut through traffic between arterial streets.
4. Road access (i.e., stub streets) to adjacent vacant properties shall be located in a manner that will allow for the connection to the adjacent vacant parcel without conflicting with resources as identified in the site inventory.
C. General Functional Classification Categories. The following identifies the basic characteristics of the three general categories within the functional classification system as outlined in the IDOT BLRS Manual:
1. Arterial. Arterial highways are generally characterized by their ability to quickly move relatively large volumes of traffic, but often with restricted accessibility to abutting properties. The arterial system typically provides for high travel speeds and the longest trip movements. The rural and urban arterial systems are connected to provide continuous through movements at approximately the same level of service.
2. Collector. Collector routes are characterized by a relatively even distribution of access and mobility functions. Traffic volumes and speeds are typically lower than those of arterials.
3. Local. All public roads and streets not classified as arterials or collectors are classified as local roads and streets. The many points of direct access to adjacent properties characterize local roads and streets. Speeds and volumes are usually low and trip distances short.
D. Road Design Standards.
1. Grade. The maximum grade for collector streets and streets of higher classifications shall not exceed four percent (4%). The maximum grade for local streets shall not exceed six percent (6%). The maximum grade for all driveways continuing outside of the right-of-way shall not exceed eight percent (8%) unless written approval is obtained from the local jurisdictional agency. The minimum grade of all streets shall be four-tenths percent (0.4%).
2. Geometrics. Street geometrics shall conform to the design standards established in the IDOT BLRS Manual. Streets shall be designed on the basis of the following design speeds:
a. Collector street: Fifty (50) miles per hour.
b. Local streets: Thirty (30) miles per hour.
3. Horizontal Curvature. Angles on the centerlines of streets shall not be permitted except at intersections. Centerline radii shall be as follows:
a. Collector streets: Shall conform to standards set by the IDOT BLRS Manual.
b. Local streets: One-hundred-foot (100') minimum.
4. Vertical Curvature. Vertical curves shall be required at all locations where the algebraic difference of grade is one percent (1%) or greater. Vertical curves shall be designed as follows:
a. Collector streets: Shall conform to standards set by the BLRS Manual.
b. Local streets: Crest vertical curves shall be designed with a minimum K value of thirty (30). Sag vertical curves shall be designed with a minimum K value of fifty (50). In no case shall a vertical curve at a street intersection be less than fifty (50) feet.
5. Minimum Radii. Minimum intersection radii shall be as follows:
a. Local and collector street: Right-of-way line of thirty-five (35) feet and pavement of fifty (50) feet.
b. Local streets: Right-of-way line of fifteen (15) feet and pavement of thirty (30) feet.
c. Local and major arterial street: As determined by IDOT and the local jurisdictional agency.
6. Rights-of-Way and Pavement Width Requirements. The following right-of-way and pavement minimum widths are required. Pavement width is calculated as the total paved area.
a. Collector Street.
(1) Right-of-way: One hundred (100) to one hundred sixty (160) feet.
(2) Pavement: Thirty-four (34) feet.
b. Local Street.
(1) Right-of-way: Sixty-six (66) feet for open drainage and sixty (60) feet for closed drainage.
(2) Pavement: Twenty-two (22) feet.
a. Pavement materials and construction shall comply with current specifications, as defined in the IDOT Standard Specifications and District 1 Region 1 supplemental specifications for subdivision pavement structure of residential subdivisions.
b. Rigid (e.g., Portland Cement Concrete), Flexible (e.g., Asphalt), or Composite (e.g., HMA surface course overlaying a PCC slab) pavement may be utilized.
c. Asphalt shall comply with the current performance based standards established by IDOT BLRS. This includes but is not limited to current IDOT mix design tables, IDOT District 1 Special Provisions and IDOT BDE Special Provisions.
d. Pavement Cross Section.
(1) Subgrade. The subgrade is the prepared and compacted soil immediately below the pavement system. This soil shall be prepared to the lines and grades indicated in the plans in accordance with the local jurisdictional agency requirements, then tested utilizing a proof rolling method in compliance with the local jurisdictional agency standards. Areas not in compliance shall be removed and replaced with suitable granular material in compliance with current District 1 Region 1 requirements. The local jurisdictional agency must approve the subgrade prior to installation of the pavement structure.
(2) Pavement Structure - Sub-Base, Base Course, and Surface Course. A combination of sub-base, base course, and surface course shall be placed on a subgrade to support the traffic loads and distribute the load to the roadbed. The sub-base, base course, and surface course shall be prepared to the lines and grades indicated in the plans in accordance with the local jurisdictional agency requirements, then tested in compliance with the local jurisdictional agency standards.
e. Commercial and Industrial Subdivisions. The pavement structure of all commercial and industrial subdivisions shall be designed on a site-by-site basis, in accordance with the IDOT BLRS Manual for eighty-thousand-pound (80,000 lb.) street weight limits.
f. Residential Subdivisions.
(1) Collector Street. Pavement structure requirements for a collector street shall be in accordance with the IDOT BLRS Manual for eighty-thousand-pound (80,000 lb.) street weight limits.
(2) Local Street.
(a) The minimum aggregate base course thickness shall be twelve (12) inches.
(b) The minimum asphalt binder course thickness shall be two and one-quarter (2 ¼) inches.
(c) The minimum asphalt surface course thickness shall be two (2) inches.
8. Cul-de-Sacs. When cul-de-sacs are permitted, they shall comply with the following minimum standards:
a. Right-of-way radius: Sixty-six (66) feet.
b. Pavement radius: Fifty (50) feet.
c. Entrance radius: Twenty (20) feet.
d. Maximum block length: Six hundred (600) feet.
e. Any medians within a cul-de-sac require written approval from the township highway commissioner.
9. Storm Sewer System. A storm sewer system in compliance with the McHenry County Stormwater Management Ordinance shall be constructed as necessary to insure satisfactory drainage of surface water throughout the subdivision and adjacent areas.
a. When ditches are installed, ditches shall be constructed along each side of the roadbed and drainage structures installed as necessary to insure satisfactory drainage of surface water throughout the subdivision and adjacent areas. The sizes of all drainage structures are computed by using accepted engineering methodology in compliance with the McHenry County Stormwater Management Ordinance. All drainage structures shall be installed before surfacing material is placed.
(1) Cross-road culverts shall have a minimum diameter of eighteen (18) inches and run from ditch line to ditch line. Driveway culverts shall have a minimum diameter of fifteen (15) inches. All culverts shall be installed with flared end sections unless otherwise permitted by the township highway commissioner.
(2) The length of culvert with end section shall be determined by the transition of grade from roadway to adjacent ditch flowline at a one to four (1:4) (vertical:horizontal) slope. The culvert shall be installed such that the end section shall match this slope.
(3) Pipe culverts shall be reinforced concrete and shall comply with the applicable sections of the IDOT Standard Specifications and Highway Standards. Other culvert pipe materials may be used with approval of the local jurisdictional agency.
b. Curbs and gutters require approval in writing from the applicable township highway commissioner. When curbs and gutters are provided, they may be either of the barrier type (B-6.12) with depressed entrances or the mountable type (M-4.12). They shall conform with the applicable sections of the IDOT Standard Specifications and Highway Standards. When a depressed type of entrance is to be provided, the following shall apply:
(1) The depressed width shall be specified by the local jurisdictional agency.
(2) The depression shall be to a height of one and one-half (1½) inches above the curb flow line.
(3) The transition from full curb height to depressed curb shall be a minimum of three (3) feet unless otherwise specified by the local jurisdictional agency.
c. For conservation design subdivisions, the use of enclosed curb, gutter, and storm sewer systems are strongly discouraged in favor of vegetated swales. In instances where curb and gutter is required, depressions shall be provided to enable stormwater to drain to the vegetated swales.
10. Shoulders. Unless otherwise waived, shoulders shall be required along all streets not provided with curbs and gutters. The shoulder shall comply with the following minimum standards:
a. The material shall be crushed virgin aggregate, type B unless otherwise specified by the local jurisdictional agency.
b. The width shall comply with the IDOT BLRS Manual for the type of roadway classification.
c. Shoulders along any county or township road designated as an official bicycle route by a township or County ordinance shall be a minimum of two (2) feet in width and be constructed with a paved surface.
11. Sidewalks. Sidewalks require approval in writing from the applicable township highway commissioner. When sidewalks are provided, they shall be located one (1) to four (4) feet inside the right-of-way line, shall be at least four (4) feet in width and four (4) inches in thickness, except where sidewalks cross driveways and intersections where sidewalks must be five (5) inches in thickness. Sidewalks shall be constructed on a four (4) inch Aggregate Base Course, Type B. Sidewalks shall be constructed to meet all applicable American with Disability Act (ADA) standards.
12. Parkway Restoration. All ground surfaces within the right-of-way disturbed by the construction operations shall be temporarily and permanently stabilized with topsoil and seed in accordance with the McHenry County Stormwater Management Ordinance.
a. Topsoil. The topsoil shall free of contaminates comply with the IDOT Standard Specifications. The thickness shall be a minimum of four (4) inches unless otherwise specified by the local jurisdictional agency.
b. Seeding. The seeding mixture shall comply with the McHenry County Stormwater Management Ordinance. The seeding shall be fertilized and mulched for stabilization and to ensure establishment with materials in accordance with the IDOT Standard Specifications.
13. Maintenance of Traffic. Traffic shall be maintained at all times in accordance with the applicable IDOT Highway Standards. Maintenance of traffic plans may be required as determined by the local jurisdictional agency.
14. Traffic Control and Street Signs. The subdivider shall furnish and erect all necessary traffic control and street signs, as designated necessary by the local jurisdictional agency. All signs shall be of a type approved by the local jurisdictional agency.
E. Roads Construction, Maintenance, and Acceptance.
1. No road construction work may be started until a final plat is approved by the County Board and recorded.
2. An Illinois licensed professional engineer shall oversee the project to assure that construction of the engineering improvements is accomplished in accordance with the approved plans and specifications.
3. During construction of streets with curb and gutter, the subdivider shall not be allowed to partially install pavement below the gutter elevation during construction operations. The subdivider shall be required to maintain positive drainage throughout construction and install pavement up to the finished gutter elevation on a temporary basis. A temporary cross slope of less than two percent (2%) is allowable during construction operations to match the gutter elevation. At the conclusion of construction, the subdivider shall remove the appropriate thickness of the pavement surface in order to establish the final approved cross-section of the roadway.
4. The subdivider is responsible for maintaining and repairing all roads in the subdivision until the roads are accepted by the appropriate authority. Maintenance includes snow plowing, which shall ensure ingress and egress to all lots that have been sold. Failure to ensure adequate ingress and egress is cause for withholding of building permits and the approval of additional units of the development.
5. Subdivision roads will not be accepted by the local jurisdictional agency until all construction detailed in the plans is completed. It is the responsibility of the subdivider to consult with the local jurisdictional agency before the work has begun to afford the local jurisdictional agency an opportunity to inspect the work as construction progresses.
6. When roadside drainage facilities include Class V injection wells, adequate precaution shall be taken to insure against siltation of the Class V injection wells until protective vegetation has become established in the ditches, and overflow provisions provided to prevent roadway flooding.
7. The asphalt surface course shall only be applied after the subdivider has received written approval from the local jurisdictional agency.
(Ord. O-201410-10-035, passed 10-14-2014; Ord. O-201601-ZBA-006, passed 1-19-2016; Ord. O-201603-ZBA-010, passed 3-17-2016, § 19.5; Ord. O-201803-ZBA-10-08, passed 3-19-2018; Ord. O-201808-10-033, passed 8-21-2018)