All public streets shall be designed in accordance with the requirements presented in this section.
(A) Compliance with state specifications. Unless stated otherwise in this section, the street design, materials and construction shall comply with the most current Illinois Department of Transportation (IDOT) edition of "Standard Specification for Road and Bridge Construction", Bureau of Local Roads and Street Manual, Bureau of Design and Environment Manual, Construction Manual or other publications promulgated by the Illinois Department of Transportation.
(B Minimum street design requirements. The minimum design speed for use with the IDOT publications shall be based on the design average daily traffic (ADT). The preferred minimum design speed for road improvements shall be 30 miles per hour. The use of any other design speeds higher or lower may be granted or required through the variance procedure.
(1) Determination of design ADT. Design ADT shall be determined using trip generation rates, equations and data plots for the subdivision type and density to be developed as determined in the current edition of "Trip Generation" by the Institute of Transportation Engineers or similar publication.
(2) Pavement design. The design period for all pavements shall be 20 years or greater. The vehicular traffic volumes and vehicle classification percentages used in the design shall be approved by the Director of Engineering. A sub-grade support rating of "Poor" shall be used in the pavement design unless the design engineer submits soil tests justifying a different rating. A sub-grade modulus (ERI) of 2 ksi shall be used in the pavement design unless the design engineer submits soil tests justifying a different rating.
(3) Pavement width and material requirements. The following table and sample plans set forth the minimum pavement requirements. The owner may construct streets with a higher classification than required, if so desired:
Classification | Lots or Units Per Acre | R O W | Pavement Width1 |
Edge Treatment | Edge of Pavement Radius | Maximum Grade | Vertical Curve Alg. Diff. | Concrete
Pavement3 |
Asphalt Pavement |
Classification | Lots or Units Per Acre | R O W | Pavement Width1 |
Edge Treatment | Edge of Pavement Radius | Maximum Grade | Vertical Curve Alg. Diff. | Concrete
Pavement3 |
Asphalt Pavement |
Local Residentia l | <1 | 50' | 26' | V-curb w/ 8' earth shld | 25' | 12% | 30 sag 20 crest | 6½" PCC w/4" agg base Subbase 4 | 1½ "surfac e 1½ " binder 8" agg base Subbase 4
|
Local Rural Residentia l | <1 | 66' | 24' | 4' earth shld with open ditches | 20' | 12% | 30 sag 20 crest | 6½" PCC w/4" agg base Subbase 4 | 1½ "surfac e 1½ " binder 8" agg base Subbase 4 |
Local Residentia l Collector | <1 | 60' | 32' | V-curb w/ 8' earth shld | 25' | 12% | 30 sag 20 crest | 6½" PCC w/4" agg base Subbase 4 | 1½ "surfac e 1½ " binder 8" agg base Subbase 4 |
Collector | <1 | 80' | 40' | V-curb w/ 8' earth shld | 25' | 12% | 30 sag 20 crest | 8" PCC w/4" agg base Subbase 4 | 1½ "surfac e 4" binder 8" agg base Subbase 4 |
Commerci al/ Industrial | 60' | 36' | V-curb w/ 8' earth shld | 30'2 | 8% | 40 sag 30 crest | 8" PCC w/4" agg base Subbase 4 | 1½ "surfac e 4" binder 8" agg base Subbase 4 | |
CBR | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
K | 50 | 100 | 120 | 145 | 155 | 170 | 180 | 190 | |
Cone Index.
psi |
40 | 80 | 120 | 160 | 200 | 240 | 280 | 320 | 360 |
CBR = Cone Index, psi/40 REMEDIAL GUIDANCE
Depth | Procedure | Increases "K" by: |
4" | undercut & aggr backfill or geogrid or geotextile | 30 |
6" | undercut & aggr backfill | 40 |
9" | undercut & aggr backfill | 60 |
12" | undercut & aggr backfill | 90 |
(4 ) All streets shall be graded to their full right-of-way width.
(5 ) Street surfacing shall not be completed until all utilities and sewers constructed in trenches have been fully installed in the street and to the property line.
(6 ) All hot mix asphalt pavement shall be constructed in accordance with the latest IDOT edition of "Standard Specifications for Road and Bridge Construction" and the Construction Manual. The hot mix asphalt surface course shall not be installed until at least 50% of the dwelling units in the subdivision are completed, or no later than two years after installation of the first layer of asphalt. The Director of Engineering shall determine if a bituminous prime coat or base repairs are required prior to applying the surface layer. Manhole, water valve and other utility castings installed above the bituminous base course shall have a temporary ramped surface with a maximum slope of one-half inch per one foot placed around the casting to prevent damage to vehicles and allow snow plowing until the bituminous surface course is placed. The temporary ramp shall be removed prior to placement of the bituminous surface course.
(7) Portland cement concrete pavements shall be constructed in accordance with the latest IDOT edition of "Standard Specifications for Road and Bridge Construction" and the Construction Manual. Portland cement concrete pavements shall only be accepted once all testing has been completed on all phases and submitted to the Director of Engineering for review. Portland cement concrete surfaces shall be evaluated over a two-year period for cracks due to settlement and spalling. Any areas that are deemed deficient by the Director of Engineering shall be removed and replaced at developer's expense.
(8) When a subdivision abuts or connects to a designated street as shown on the Major Street Map, any new pavement within the right-of-way of the new street shall be constructed to the standards of the existing or proposed designated street pavement for its classification or for the subdivision standard, whichever is greater. If the designated street is proposed by the Director of Engineering for construction or reconstruction within three years of the date of the approval of the subdivision, then the new pavement abutting the designated street shall be constructed to a standard equal to the proposed pavement structure standards per the IDOT Bureau of Local Roads standard for the designated street's classification.
(9) All contractors making street improvements on State of Illinois rights-of-way shall provide the Director of Engineering proof of the required permit bonding for such improvements.
(10) Supervision and inspection. Construction shall begin only after approval of the construction plans. The Director of Engineering shall be notified at least 48 hours before construction begins and prior to any resumption of construction after delays or halts of longer than seven days.
(C) The owner shall provide a qualified individual who shall be responsible for establishing the proper lines and grades for all earthwork and drainage. Information regarding the layout to establish the proper lines and grades for all earthwork and drainage shall be provided to the Director of Engineering for verification and quality assurance of the completed construction. Proposed changes or any remedial actions to be taken that differ from the approved plans must be submitted to the Director of Engineering for approval.
(D) The owner shall have a qualified resident observer present on the site for the following:
(1) Installation and backfilling of storm sewers and appurtenances;
(2) Installation and backfilling of cross road water mains, sanitary sewers and storm sewers;
(3) Approval of the subgrade prior to aggregate placement; and continuous observation of all phases of the paving operations.
(E) The resident observer shall be familiar with the IDOT Standard Specifications for Road and Bridge Construction and the IDOT Construction Manual in order to make appropriate inspections and documentation and to provide certification that the street and drainage specifications contained herein and as referenced are met. The resident observer shall be approved by the Director of Engineering prior to beginning construction. The Director of Engineering shall conduct periodic inspection and quality assurance testing of all aspects of the field construction. An inspection fee in an amount equal to that shown on the schedule in § 161.21(C) for the estimated construction cost shall be paid to the city by the owner prior to commencement of any public improvements. The Director of Engineering shall not in any way be a substitute for the owner's engineer, inspector or resident observer.
(F) The Director of Engineering may issue a stop order on construction if it is determined that the improvements are being built contrary to approved plans and specifications or that the owner is not providing proper or thorough inspection of construction.
(Ord. 9278, passed 6-22-2015)