(A) Streets, alleys, walks, and drainage systems shall be designed in accordance with the current Illinois Department of Transportation Design Manual and Highway Standards. In addition, the following minimum requirements shall also be met for the design of streets, alleys, and walks in any new subdivision within the city or within contiguous territory which is not more than one and one-half miles beyond the corporate limits of the city:
(1) The grades of collector streets shall not be steeper than 3%. The grades of all other streets shall not be steeper than 5%. No street grade shall be less than 0.3%.
(2) All streets, all alleys, and all public walks for pedestrian travel shall be graded and the surface thereof improved with pavement. Street pavement shall be bounded by curbs, gutters, or combination curbs and gutters.
(3) The minimum width of improved paved areas of streets measured from curb face to curb face shall be as follows:
(a) Collector street, 44 feet.
(b) Local streets, the pavement width of local streets in single family residential areas with lot size greater than 15,000 square feet shall be 24 feet measured curb to curb. In single family residential areas with lot size less than 15,000 square feet but greater than 6500 square feet the local street width shall be 27 feet measured curb to curb. In multi-family residential areas and in areas with lot size less than 6500 square feet the street width shall be 34 feet measured curb to curb.
(c) Permanent turnarounds at the end of a cul-de-sac, the outside diameter of the surfaced area of a turnaround shall be not less than 80 feet.
(4) The minimum width of improved paved areas of alleys to serve business, commercial, and industrial areas shall be 20 feet.
(5) Pavements for collector streets may be constructed with either portland cement concrete or asphalt cement concrete. If constructed with portland cement concrete, the pavement shall be not less than seven inches thick with wire reinforcement on top of eight inches of aggregate base, Type B. Transverse contraction joints shall be constructed in the slab at 20-foot intervals. Load transfer devices are not required at the transverse contraction joints. Longitudinal contraction joints shall be constructed in the pavement on the center line for collector streets with parking on one or two sides. The pavement and contraction joints shall be designed as shown in Standard 2179 of the Illinois Department of Transportation Highway Standards. If constructed of bituminous materials, the pavement shall consist of six and one-half inches of asphalt concrete on top of eight inches of aggregate base type B. Should subgrade conditions warrant additional treatments as determined by the City Engineer, additional sub-base material will be required. If contractor desires to vary from the minimum thickness of the aggregate base, as set forth above, then contractor may so vary provided that the base used meets the following-described performance standard and testing, which testing shall be at the expense of contractor: Prior to commencement of pavement, the subgrade shall have a CBR of at least 6% in the top of 12 inches of subgrade, provided that the subgrade is within 1/10th of a foot of final grade; and further provided that contractor shall provide independent testing via a dynamic cone pentrometer (DCP) with one test every 50 feet of road alternating between the two traffic lanes to a depth of at least three feet below finish grade.
(6) Pavements for local streets may be constructed of portland cement concrete or asphalt cement concrete not less than six inches thick, or asphalt cement concrete not less than six inches thick, both on six inches of aggregate base type B. If constructed of P.C. concrete, transverse contraction joints shall be constructed in the slab at 20 foot intervals and longitudinal contraction joints shall be constructed on the centerline and 10 feet on either side of centerline for local streets with parking on two sides. The contraction joint may be formed with a polyethylene strip one and one-half inches wide, or may be saw cut as shown in Illinois Department of Transportation Highway Standard 2179. Should subgrade conditions warrant additional treatment as determined by the City Engineer, additional sub-base materials shall be required. If contractor desires to vary from the minimum thickness of the aggregate base, as set forth above, then contractor may so vary provided that the base used meets the following-described performance standard and testing, which testing shall be at the expense of contractor: Prior to commencement of pavement, the subgrade shall have a CBR of at least 6% in the top 12 inches of subgrade, provided that the subgrade is within 1/10th of a foot of final grade; and further provided that contractor shall provide independent testing via a dynamic cone pentrometer (DCP) with one test every 50 feet of road alternating between the two traffic lanes to a depth of at least three feet below finish grade.
(7) Curbs and gutters shall be required for all city streets. The curbs and gutters shall be constructed of portland cement concrete not less than six inches thick. On collector streets the curb shall be constructed to the dimensions given for Type B6.18 curb and gutter as shown in the Illinois Department of Transportation Highway Standard 2130. On local streets the curb shall be constructed to the dimensions given for mountable curb and gutter as shown in Illinois Department of Transportation Highway Standard 2130 or as shown in City Standard No. 3. When portland cement concrete is used for the roadway pavement, the curbs may be constructed integrally with the pavement.
(8) All curb corners shall have a radius of not less than 25 feet measured to the face of the curb.
(9) Sidewalks shall be constructed on both sides of all public streets. All public walks designed for pedestrian travel shall be constructed of not less than four inches of portland cement concrete. On collector streets the walks shall be five- feet wide, on local streets the walks shall be four-feet wide.
(10) All streets shall be provided with complete underground drainage facilities having a design capacity adequate to carry off surface water falling on or coming on the area involved for a five-year storm, as that design is defined and used in the publications of the State Water Survey Division of the Department of Registration and Education of the State of Illinois.
(B) However, the City Council may approve exceptions to the requirements of this section and approve plans for design of streets pursuant to these exceptions when such are more consistent with the city facilities and in accordance with good engineering practice, as determined by the City Engineer.
(Am. Ord. 95-O-1, passed 3-13-95) Penalty, see § 52.99