2 Del. Admin. Code § 5.6
Pavement sections are to be designed based on the ADT utilizing the planned roadway and the existing subsurface conditions. Acceptable pavement sections are to be designed based on assuming poor soils. If the applicant wishes to propose pavement sections based upon anything other than poor soils, soil testing may be performed, at no cost to DelDOT, by an accredited lab with DelDOT supervision of testing. This request shall be made prior to preliminary plan submission. The pavement sections listed in Figures 5.6.1-a and 5.6.2-a are designed to meet the required Structural Numbers (SN) and meet the following conditions/criteria:
The binder grade and gyrations of mix for bituminous concrete (asphalt) pavements will be specified on a project basis during the review process and must be indicated on the plans.
Materials placed for construction of roadways in subdivisions, entrances, and industrial roadways must not be constructed in lifts that violate DelDOT's minimum and maximum lift thickness. The allowable lift thickness and structural values for materials used are shown in Figure 5.6-a.
Figure 5.6-a Material Properties
All subdivision streets and entrances shall be paved with bituminous asphalt concrete or Portland cement concrete surface. Pavement sections for internal subdivision streets are to be built to serve the traffic generated from the development upon completion, including all construction related traffic of the development. Should additional development phases be planned that will be connected to the portion of the development under construction, the pavement section for the street shall be such that it will support both the phase under construction and the future phases. The surface of the Type B bituminous concrete (asphalt) pavement shall be free of defects such as potholes, alligator cracking or rutting prior to the placement of the Type C bituminous concrete (asphalt) lift. Figure 5.6.1-a shows examples of pavement sections acceptable for use on internal subdivision streets.
When calculating the structural number of a pavement section, consider whether vehicular traffic used the street section previously. For example:
A subdivision has an ADT of 136. Figure 5.6-b requires that the structural number at completion be 2.98, while the pavement section in place prior to 75% completion of the development must have a structural value of 2.48. To determine the structural value of the overall section, the structural capacity of the section must be determined using SN contribution values as follows:
Thickness C = 2 3/4" (1 1/2" placed at initial pavement construction; 1 1/4" placed after DelDOT acceptance).
SN C = 0.4 per inch
Thickness B = 2 1/4"
SN b = 0.4 per inch
Thickness GABC = 7"
SN GABC = 0.14 per inch
The structural number meets the requirements structurally for the overall value and meets the conditions set forth in the beginning of this section. Once it is established that these are sufficient, the section must be verified to meet the required structural value prior to 75% completion of the development This calculation uses SN contribution values without the 1 1/4" Type C bituminous concrete (asphalt) pavement placed after DelDOT acceptance and is as follows:
Thickness C = 1 1/2"
SN C = 0.4 per inch
Thickness B = 2 1/4"
SN B = 0.4 per inch
Thickness GABC = 7"
SN GABC = 0.14 per inch
This calculation shows how the required section is calculated and may be used to adjust thickness requirements of example sections as long as all requirements are met and lift thickness values are not violated.
Figure 5.6.1-a Pavement Design Chart for Internal Subdivision Streets
Pavement sections for entrances on State-maintained roadways are to be designed using the average daily traffic using that entrance or 20% of the mainline traffic, whichever is greater (see Figure 5.6.2-a). Other sections, to be constructed in conjunction with the entrance to the highway that must be submitted for design to DelDOT are:
* Travel lanes
Right-turn lanes
* Bypass lanes
Left-turn lanes
* Crossovers
* Entrances that do not conform to the description listed in Figure 5.6.2-a for each class
* Class III entrances
Figure 5.6.2-a Pavement Design Chart for Entrances
Streets that are to be used as entrances to industrial parks must be built to State requirements. DelDOT must perform all pavement designs for proposed industrial streets, to match the design with the anticipated vehicle use.
When a trench is made to install utilities or drainage across or longitudinally along an existing shoulder or a shoulder is widened, the pavement tie-in detail shall be provided on the construction plans as shown on figure 5.6.4-a.
Figure 5.6.4-a Pavement Tie-in Detail
When widening is proposed for auxiliary lanes or shoulders or utilities are to be installed longitudinally on roadways, any encroachment of one foot or more onto a travel lane requires restoration of the full lane width as shown on figure 5.6.4-b.
Figure 5.6.4-b Lane Widening/Restoration Detail
2 Del. Admin. Code § 5.6
15 DE Reg. 551 (10/01/11)
16 DE Reg. 1199 (5/1/2013)
18 DE Reg. 240 (9/1/2014)
18 DE Reg. 709 (3/1/2015)
19 DE Reg. 938 (4/1/2016) (Final)