Chapter 4 - Design and Construction Standards for Streets
4.01 Introduction
4.02 General Requirements
4.03 Right-of-way Dedication
4.04 Design Standards
4.05 Specifications and Special Provisions
4.06 Standard Details
4.01 INTRODUCTION
All lots in any subdivision, regardless of size, shall front on a street. When necessary, streets shall be included as part of the subdivision and shall be designed and constructed in accordance with this chapter.
4.02 GENERAL REQUIREMENTS
All subdivisions shall be designed so the proposed street system accomplishes the following:
- Conforms with the Town of Normal Comprehensive Plan.
- Extends arterial and collector streets through the proposed subdivision.
- Locates and aligns local streets so that use by through traffic is discouraged.
- Avoids centerline offsets of less than 250 feet (75m) from other streets or roadways for local streets. For offsets from arterial/collector streets a more detailed engineering study may be required.
- Where the angle of deflection in horizontal centerlines
exceeds five degrees, a curve shall be inserted with a radius
of not less than the following dimensions, depending on the
classification of the street involved:
- Local street – 65 feet (20m)
- All others as per IDOT.
- So that not more than two streets intersect at any point and so that the angle of intersection of centerlines is not less than 80 degrees or more than 100 degrees.
- In single-family zoning districts so that cul-de-sacs do not exceed 1200 feet (365m) in length or have more than 15 lots fronting thereon, whichever imposes the more demanding standard and in multiple-family and two-family zoning districts so that cul-de-sacs do not exceed 400 feet (120 m.) or have more than 8 lots fronting thereon, whichever imposes the more demanding standard.
- Encourage safe and efficient traffic flow and provide sufficient vehicular storage space for stopping and turning movements so as not to conflict with traffic at intersecting streets or driveway entrances.
- In residentially zoned areas access to an arterial or collector street shall be provided every 1200 feet (365 m.) or no more than 1800 (550 m.) as measured along the arterial or collector street.
- The minimum curb radius where two streets intersect shall be 7.6 meters (25 feet) to face of curb. For arterial, collector, and local commercial streets, curb radii shall be sufficient to accommodate the appropriate design vehicle in accordance with Illinois Department of Transportation “Design and Environment Manual”.
- Cul-de-sac streets shall not be constructed “back to back”. (Back yards on one cul-de-sac may not be adjacent to back yards of another cul-de-sac).
- Lots zoned R-1C or R-2 shall have a minimum 18-meter (60 feet) lot width measured at the building setback line if located on the bulb of a cul-de-sac street.
- Driveways shall not encompass more than 50% of the curb on the bulb of a cul-de-sac street.
4.03 PUBLIC STREET RIGHT-OF-WAY DEDICATION
- All streets and roadways proposed within the confines of
a subdivision shall be located in dedicated public or private
right-of-way as required by this section. All streets are considered
public unless specifically stated that they are private on the
preliminary plan and final plat.
- Interior Streets--subdivisions shall be designed
so all interior streets are located within dedicated public
rights-of-way of the following minimum widths, depending on
the street classification, the volume of traffic and the zoning
of the abutting property (where side streets abut two or more
zoning districts, right-of-way dedication shall be provided
so as to meet the requirement of the more demanding zoning district):
Expressway In accordance with the Comprehensive Plan of the Town of Normal or Interstate the standards and requirements of the Federal, State, County or Township authorities having jurisdiction, whichever has the greater right-of-way width requirement.Type of
StreetR-1 and R-2
Zoning DistrictsR-3
Zoning DistrictsB, C. M
Zoning DistrictsArterial Over 1200 D.V. 96 feet (29 m.) 96 feet (29 m.) 96 feet (29 m.) Under 1200 DHV 86 feet (26m.) 86 feet (26 m.) 86 feet (26 m.) Collector 80 feet (24m.) 80 feet (24 m.) 90 feet (27 m.) Local 60 feet (18m.) 60 feet (18m.) 70 feet (21 m.) 4-Lane Divided With median 100 feet (30 m.) 100 feet (30 m.) 100 feet (30 m.) Cul-De-Sac (Dia.) 100 feet (30 m.) 100 feet (30 m.) 120 feet (34 m.) Frontage Roads 60 feet (18 m.) 60 feet (18 m.) 60 feet (18 m.)
Private Streets. Subdivisions shall be designed so all interior streets are located within dedicated right-of-way of the following minimum width:
- Street without sidewalk: One meter (3 ft.) back of curb to one meter (3 ft.) back of curb.
- Street with one adjacent sidewalk: Back of sidewalk to one meter (3 ft.) back of curb.
- Street with two adjacent sidewalks: Back of sidewalk
to back of sidewalk.
- Exterior Streets--subdivisions shall be designed
so that the subdivider provides not less than one-half the right-of-way
dedication required for a comparable interior street.
- Supplemental Dedication--where the street design requirements of this ordinance require the provision of turning lanes, turning radii, center median, traffic control devices or other installation which cannot be installed within the right-of-way otherwise required by this Code without the elimination or conflict between such features and other public improvements, the subdivider shall dedicate such additional right-of-way as is necessary to accommodate all such improvements.
4.04 DESIGN STANDARDS
- Street Width
Pavement width shall be based on street classification, the expected traffic volume and the zoning district (the more demanding standard shall apply) in accordance with the following:
Street (face to face of curb)
Pavement WidthMedian
WidthArterial *Over 855 DHV
51 ft. (15.4 m.) 4 (1.2 m.) *495-855
47 ft. (14.1 m.) 0 *Under 495
36 ft. (11.0 m.) 0 Collector *Over 495
47 ft. (14.1 m.) 0 *Under 495
36 ft. (11.0 m.) 0 Local 30 ft. (9.0 m.) 0 Frontage Roads 30 ft. (9.0 m.) 0 Boulevards 2 @ 6.6 m (2 @ 22 ft) 0 One-Way 24 ft. (7.2 m.) 0 Private Street R-1, R-2 Zoning
9.0 m (30 ft.) R-1, R-2 Zoning
7.2 m (24 ft.) (if no parking allowed) All other zoning
9.0 m (30 ft.)
- Pavement Structure
Structural strength shall be based on street classification, the expected traffic volume and designed in accordance with current:- Illinois Department of Transportation “Design and Environment Manual”
- Illinois Department of Transportation “Highway Standards”
- Illinois Department of Transportation “Standard Specifications
for Road and Bridge Construction”
Local streets shall be constructed with a minimum of ten (10) inches (250mm) of compacted crushed aggregate and three (3) inches (75 mm) of bituminous concrete surface, or six (6) inches (150mm) Portland Cement Concrete, installed in accordance with “Standard Specifications For Road And Bridge Construction” in accordance with the following design and construction standards and specifications:
- Cul-de-Sac Terminus
Cul-de-sac terminus shall have a minimum diameter measured face-to-face of curb eighty (80) feet (24 m) in areas zoned residential and one hundred (100) feet (30 m) in all other areas.
- Vertical Gradients
Differing connecting street gradients shall be connected with vertical curves. The "Design and Environment Manual" shall govern all vertical curve computations, except when the algebraic difference of the gradient is less than one (1) percent a fifty -(50) foot vertical curve length shall be utilized. Desirable street gradients shall not be less than a minimum of 0.50% (five tenths of one percent). In no case shall the street gradient be less than 0.40%.
- Curb and Gutter
- Curb and gutter shall be Type B-6.18 (B15.45) in accordance with the "Illinois Department of Transportation Highway Standards" and installed in accordance with the "Standard Specifications of Road and Bridge Construction".
- All curb and gutter shall be designed so as to facilitate
persons using wheelchairs to travel freely and without assistance
by providing at each crosswalk a ramp with non-slip surface
so that the sidewalk and street blend to a common level.
Such ramp shall be designed and constructed in accordance
with the "Highway Standards".
- Trench Backfill
Any excavation in an existing or proposed street shall be backfilled with trench backfill or controlled low strength material.
4.05 SPECIFICATIONS & SPECIAL PROVISIONS
All streets and curb and gutter shall be constructed in accordance with all applicable sections of the "Standard Specifications for Road and Bridge Construction" for the Illinois Department of Transportation, the current edition as then modified, supplemented and amended by this Manual or the Town Engineer. These modifications, amendments and amplifications have been provided in this Chapter of the Manual.
Street Special Provisions
Curb marking of Water and Sewer Services: At the time the curb and gutter is poured, the contractor shall mark the top of the curb with an "S" or "W" for sewer and water services respectively.
Adjustment of Frame of Grate: Final grade for all manhole castings will be determined after the curb and gutter has been poured and the sub-grade and/or base have been constructed. Final adjustment of the frame and grate shall be made in the following manner: After the curb and gutter has been poured and the base constructed the final elevation will be determined by the Town Engineer.
The frame and grate will be adjusted to this elevation in accordance with the Standard Specifications for Road and Bridge Construction. Any material disturbed while adjusting the frame and grate will be disposed of and all fill made with lean concrete. A maximum of eight (8) inches of adjusting rings shall be allowed.
Coarse Aggregate: Shall comply with IDOT specifications.
Combination Concrete Curb and Gutter: Concrete curb and gutter shall be sawed or scored at intervals coinciding with the joint intervals of the adjoining pavement. The minimum joint depth for the gutter shall be two (2) inches (50 mm.), and one (1) inch (25 mm.) for the curb. The curb and gutter may be jointed instead of sawed provided the stated joint depths are obtained. If the curb and gutter is adjacent to bituminous pavement it shall be jointed at fifteen (15) foot (4.5 m.) intervals.
The sawing of the curb and gutter shall commence within four (4) hours of the start of the pour unless otherwise directed by the Engineer. Sawing shall continue until all joints are completed.
Asphaltic type expansion joints one (1) inch (25 mm.) thick shall be placed at all P.C.'s, P.T.'s and R.P.C.'s and at maximum 150 meter (500') intervals.
Test Rolling of Sub-grade and Base Course: The contractor will provide at his own expense a loaded truck and test roll the compacted earth sub-grade in the presence of the Engineer or his designee before any sub-base, base, or surface is placed. The truck shall be loaded as follows: 27,000 pounds (12,000 kg.) on two axles and 45,000 pounds (20,000 kg) on three axles, plus or minus ten percent.
The truck shall make one pass over the entire length of each traffic lane to be constructed. Areas that show rutting, cracking or rolling will not be accepted. The contractor will re-compact and/or reconstruct the sections that fail and test roll again for acceptance.
When bituminous or concrete surface courses are to be placed over an aggregate base, the base shall be test rolled prior to placement of the surface course.
Portland Cement Concrete Pavement: Sawed transverse joints shall be not greater than fifteen (15) feet apart and shall conform to the details in the plans. All equipment and labor required to perform the necessary jointing operation shall be available to begin sawing no later than four (4) hours after the paving operation begins, unless excess raveling occurs. The contractor shall provide the necessary equipment and labor needed to complete the sawing at the same rate per longitudinal foot as the paving operation.
The contractor shall stop the paving operation at 4:30 P.M. unless approved otherwise by the Town Engineer. Sawing shall continue at the same rate as stated above until the sawing is complete or the pavement has set.
Trucks and mixer trucks will be allowed to operate on the sub-grade; however, should the sub-grade show any signs of distress, all operations will cease until these items are corrected to the satisfaction of the Engineer. Curb and gutter is to be formed in a separate operation from the pavement. Monolithic curb is permitted.
Final finish shall be Type B, as described in the Standard Specifications for Road & Bridge Construction.
Portland Cement Concrete Driveway Pavement: Pavement shall be a minimum of six (6) inches (150 mm.) in depth. Sawed transverse and longitudinal joints shall conform to the following table:
| Driveway Width at Widest Point | No. of Longitudinal Saw Cuts |
| 0' - 12' (0 M – 4M) | 0 |
| 12' - 24'(4 M – 8 M) | 1 |
| 24' - 36' (8 M – 16 M) | 2 |
| Maximum Driveway Length | Number of Transverse Saw Cuts |
| 0' - 12' (0 M – 4 M) | 0 |
| 12' - 24'(4 M – 8 M) | 1 |
| 24' - 36' (8 M – 16 M) | 2 |
The sawed joints shall be spaced evenly throughout the driveway.
The joints
shall be 1/8 inch (3 mm.) wide with a minimum depth of T/4 and the
depth of the pavement and sealed with the same material and in the
same manner as Portland Cement Concrete Pavement.
3/4" (20 mm.) thick expansion joints shall be placed between driveway pavement and sidewalks and between driveway pavement and curb and gutter.
