Street construction design is based upon the California bearing ratio, hereinafter referred to as “CBR”, value of the soil sub-grade. Where more than one soil type of varying CBR value occurs on the proposed street, design shall be made on the basis of the lowest CBR. While actual on-site testing is recognized as a proper method of determining CBR values, the use of soil types may be utilized in lieu of on-site testing as a satisfactory substitute. For purpose of street construction standards, Table 9 below shows three classifications of soil with its engineering design calculation.
Table 9: Minimum Pavement Composition (Thickness Expressed in Inches)
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Local Street (n=5)* | Collector Street (n=10) | Minor Arterial Street (n=35) | Major Arterial and Industrial (n=75) | ||||||||||
CBR | 3-6 | 6-10 | 10+ | 3-6 | 6-10 | 10+ | 3-6 | 6-10 | 10+ | 3-6 | 6-10 | 10+ |
Table 9: Minimum Pavement Composition (Thickness Expressed in Inches)
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Local Street (n=5)* | Collector Street (n=10) | Minor Arterial Street (n=35) | Major Arterial and Industrial (n=75) | ||||||||||
CBR | 3-6 | 6-10 | 10+ | 3-6 | 6-10 | 10+ | 3-6 | 6-10 | 10+ | 3-6 | 6-10 | 10+ | |
Pavement | ODOT | ||||||||||||
Composition | Item | ||||||||||||
Aggregate Base | 304 301 448 | 6” 3.5” | 6” 3” | 5” 3” | 9” 3” 1.5” | 5” 3” 1.5” | 5” 1.5” | ||||||
Deep Strength Asphalt Base | 301 402 448 | 5” 1.5” 1.5” | 4.5” 1.5” 1.5” | 4.5” 1.5” 1.5” | 7.5” 1.5” | 5.5” 1.5” | 4.5” 1.5” | 7.5” 1.5” | 5.5” 1.5” | 4.5” 1.5” | 8.5” 1.25” 1.25” | 7” 1.25” 1.25” | 6” 1.25” 1.25” |
Concrete Base | 305 448 | 6” 1.25” | 6” 1.25” | 6” 1.25” | 6” 1.25” | 6” 1.25” | 6” 1.25” | 6” 1.50” | 6” 1.25” | 6” 1.25” | 6” 1.50” | 6” 1.50” | 6” 1.50” |
Concrete Pavement | 452 | 7” | 7” | 7” | 7” | 7” | 7” | 7.5” | 7.5” | 7.5” | 8” | 8” | 8” |
Note: The number in parentheses (after the street type) is the design traffic number and is the “n” number of 18,000 pound equivalent loads per day. When it is possible this loading will be exceeded, the County Engineer or City Manager may elect to change the roadway design specifications. | |||||||||||||
LEGEND C.B.R. = California bearing ratio (a measure of soil bearing capacity) 301 = Bituminous aggregate base 304 = Aggregate base 305 = Portland cement concrete base (5.5 bag mix) 448 = Asphalt concrete 407 = Tack coat (RS-1) 408 = Prime coat (RC-30, MC-70, RT-2, RS-1 or RS-2) 452 = Plain Portland cement concrete pavement (6.5 bag mix) | |||||||||||||
*The sub-divider may elect to place 8 inches of 304 and a sealed surface that meets the following specifications: Bottom seal - 40 pounds #67 stone per SY, rolled and compacted 0.6 gallon of 150XL emulsion or equivalent per SY Top seal - 25 pounds #8 stone per SY, rolled and compacted 0.4 gallon of 150 XL emulsion or equivalent per SY Berms shall consist of ODOT 617 | |||||||||||||
(Prior Code, § 23.05.31) Penalty, see § 151.999