SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-0(1) CHAPTER 7 PAVEMENT DESIGN 7-1.0 INTRODUCTION 7-2.0 RIGID PAVEMENT DESIGN 7-2.01 Cross Sections 7-2.02 Ramps and Loops with Storage Area 7-2.03 Major Forks, Branch Connections, and Escape Lanes 7-2.04 Bridge Approach Treatments and Panels 7-3.0 FLEXIBLE PAVEMENT DESIGN 7-2.04.01 General 7-2.04.02 High and Low Abutments on Footing 7-2.04.03 Integral Abutments 7-2.04.04 Bridge Approach Panels 7-3.01 Cross Sections 7-4.0 SHOULDER STRUCTURAL DESIGN 7-4.01 Standard Shoulders 7-4.02 Widened Pavement Shoulders
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SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-2(1) CHAPTER 7 PAVEMENT DESIGN 7-1.0 INTRODUCTION Pavement design procedures are discussed in the MnDOT Geotechnical and Pavement Manual. This chapter covers items related to pavement design not covered in that manual. 7-2.0 RIGID PAVEMENT DESIGN 7-2.01 Cross Sections Typical rigid pavement cross sections are shown in Figures 7-2.01A and 7-2.01B. Figure 7-2.01A is for two-lane and multi-lane undivided roadways. Figure 7-2.01B is for interstate and other multi-lane divided roadways. The required roadway pavement widths are shown in Table 7-2.01A. Table 7-2.01A (Dual Units) Pavement Widths Outstate Metro 2-Lane Multi-lane Undivided 4-Lane Divided 6-Lane (or more) Divided 4.1 m (13.5 ft) both lanes 4.2 m (14 ft) outside lanes 3.6 m (12 ft) interior lanes 4.2 m (14 ft) outside lane 4.0 m (13 ft) inside lane 4.2 m (14 ft) outside lane 3.6 m (12 ft) interior lanes 4.0 m (13 ft) inside lane All lanes are 3.6 m (12 ft) wide Design for the thickness of the pavement, base, and subbase materials are located in the MnDOT Geotechnical and Pavement Manual. 7-2.02 Ramps and Loops with Storage Area Standard Plans 5-297.236 and 5-297.236M provide details for concrete pavement sections of ramps with a storage area. The normal rural ramps and loop width of 4.8 m (16 ft) jointed longitudinally at midpanel, is tapered out to two 3.6 m (12 ft) lanes at the intersection of the crossroad. For urban loops, the normal width is 5.4 m (18 ft) jointed longitudinally at mid-panel. The center joint will be a L1TH for both rural and urban design. The curb design will be carried through the tapered section.
7-2(2) ROAD DESIGN MANUAL SEPTEMBER, 2006 RIGID PAVEMENT DESIGN TWO-LANE AND MULTI-LANE UNDIVIDED Figure 7-2.01A (Dual Units)
SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-2(3) RIGID PAVEMENT DESIGN MULTI-LANE DIVIDED AND FREEWAY Figure 7-2.01B (Dual Units)
7-2(4) ROAD DESIGN MANUAL SEPTEMBER, 2006 7-2.03 Major Forks, Branch Connections, and Escape Lanes Major forks, branch connections, and escape lanes require special consideration, especially with relation to longitudinal joint layouts. The following items should be included in the development of the design in Figure 7-2.03A: 1. Gore areas shall be paved with non-reinforced concrete pavement of the same thickness and panel lengths as the mainlines. For transverse construction joints use Design C2B. 2. The merging of branch connections into one roadway may result in the concrete pavement joints not being exactly parallel even if the joints merge at the center of the roadway. Therefore, place E1-1 joints until the joints are at right angles to the merged roadway. 3. The longitudinal joints in the major fork shall be labeled as E1-1, L1TH or L2KTH. The location of the E1-1, L1TH or L2KTH joint may be interchanged where required. Up to 4 lanes may be tied together with E1-1, L1TH or L2KTH joints. 4. An E1-1 or L2KTH joint may be used at the Contractor's option for the longitudinal joint in the taper area. Construct the taper as shown in Figure 7-2.03A. 7-2.04 Bridge Approach Treatments and Panels 7-2.04.01 General The design of bridge approach treatments and approach panels are the responsibility of the Road Design personnel. Approaches are broken down into two groups depending upon whether or not the structure has an abutment footing. The abutments on footing are either low abutments or high abutments. An abutment without a footing is generally considered an integral abutment. Normally, bridge approach treatments are specified at every bridge that has bridge approach panels unless recommendations to the contrary are provided by the District Soils and/or Materials Engineer in conjunction with the Office of Materials Geotechnical Engineering Section. Discussion of the use and design of bridge approach panels is found in Section 7-2.04.04. 7-2.04.02 High and Low Abutments on Footing A low abutment is defined as an abutment whose height is less than 4.5 m (15 ft) measured from the top of the deck to the bottom of the footing. A high abutment is defined as an abutment whose height is 4.5 m (15 ft) and greater measured from the top of the deck to the bottom of the footing. Details for these designs are shown in Standard Plans 5-297.233 and 5-297.233M. Additional notes of explanation are as follows: 1. The sequence of construction is shown on the Standard Plan sheets for Bridge Approach Treatment. Note in the Rough Grading Section, fill is placed to the full height and width of the roadway and then later partially removed to facilitate the construction of the abutment. Placing the fill in this manner helps insure adequate soil compaction beneath the abutment. Note in the Final Grading Section that the removed material is replaced by various types of grading materials. It is important that the quantities of these backfill materials be accurately computed and shown on the plans. 2. A perforated drainage pipe is always placed directly behind a high abutment. This drainage pipe is sometimes required for low abutments (see bridge plan). Additional drain pipes may also be required if stated in the Materials Design Recommendation Report. The designer shall provide plan details for installing and locating ALL drains and drain outlets. 3. On replacement bridges where new abutments are located at the old abutments, the full treatment per Standard Plan for Bridge Approach Treatment shall be provided unless settlements of existing approach fills and subsoils have already sufficiently occurred. The designer shall refer to the Materials Design Recommendation Report for this information. 4. Temporary drainage is required during construction of the abutment. 5. For high abutments, special erosion protection treatments shall be required for end slopes at river bridges. See Chapter 8 for recommendations. 7-2.04.03 Integral Abutments An integral abutment is defined as an abutment supported on a single line of piles with the bridge superstructure being integrally attached to the abutment. There is no footing for integral abutments. Details for this design will be shown in Standard Plans. The notes of explanation for high and low abutments listed in 7-2.04.02 shall apply to integral abutments as well.
SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-2(5) LONGITUDINAL JOINT LAYOUT MAJOR FORKS AND BRANCH CONNECTIONS Figure 7-2.03A (Dual Units)
7-2(6) ROAD DESIGN MANUAL SEPTEMBER, 2006 7-2.04.04 Bridge Approach Panels Bridge approach panels are used to connect the pavement structure with the bridge. They are provided for both concrete and bituminous pavement conditions. Bridge approach panels are to be constructed under the paving contract. Bridge approach panels are detailed on Standard Plans 5-297.223 through 5-297.232 for concrete and bituminous pavements. For concrete pavement the panel is designed with a 100 mm (4 in.) pressure relief joint between the approach panel and the roadway surfacing. The other end of the panel abuts the bridge abutment. The type of joint or connection should be coordinated with the bridge designer. A special design is required for approach panels skewed 45 degrees or greater. Panels are normally 6.0 m (20 ft) in length, with the width equal to the clear width of the bridge (mainline plus shoulder). The minimum thickness of the bridge approach slab shall be 300 mm (12 in.) for both rigid and flexible pavement design. The criteria for the use of bridge approach panels is as follows: 1. Bridge approach panels shall be constructed at all bridges on trunk highways. 2. Approach panels shall be constructed at bridges, which carry secondary road traffic over a trunk highway where any of the following conditions exist: a. The approach roadway on the secondary road has concrete surfacing. b. The traffic volume on the secondary road is in excess of 750 ADT (projected). c. There is an interchange located at the crossing. 3. Bridge approach panels shall be added to existing bridges on new construction and reconstruction projects. 4. Plans for bridges, which will not incorporate approach panels, shall specify either an appropriate length of bituminous curb at each corner of the bridge to reduce erosion at the wingwalls, or a catch basin drainage system with temporary surface drainage provisions. The roadway plans shall provide information for all adjusting rings and castings for the catch basins. If catch basins are required at bridge approaches (see Figure 7-2.04A for use of catch basins on rural sections), provide the following information: 1. Elevations of the flow line of pipe at the juncture with each catch basin. Provide minimum cover to the flow line and provide 1 percent minimum cross slope for drainage. Set elevation to incorporate the use of 50 mm (2 in.) adjusting rings with standard cones and catch basins. 2. Specify the type of erosion control at the end of the flume. The flume should extend the entire length of embankment slope, i.e. do not outlet flume at midpoint of slope. For usual grade separations, specify sod. For unusual cases (larger than normal drainage areas, flow concentrations due to superelevation, etc.), check with the Hydraulics Section. 3. Locations of drainage outlets. On bridges with divided roadways and a common median ditch, drainage should normally flow both ways from the crown. In addition, the following should be considered in the design of bridge approach panels: 1. Surfacing on approach panels should be determined by consulting with the District Materials Engineer and the Office of Materials. 2. Where city streets intersect at the end of a bridge, significant modifications of the panel are required (including possible deletion of the panel). Consult with the bridge designer. 3. All transverse and longitudinal joint sealant materials shall be hot-poured joint sealant conforming to Specification 3725. 4. All transverse and longitudinal jointsshall be designed in accordance with MnDOT Standard Plans.
SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-2(7) FOR SPECIFIC LOCATIONS CONTACT HYDRAULICS. NOTE: USE CATCH BASINS ONLY ON LOW SIDE OF SUPERELEVATED ROADWAYS. FOR CASE A, THE MINIMUM RECOMMENDED GRADE IS 0.05%. FLAT GRADES ARE UNDESIRABLE AND ARE NOT RECOMMENDED. USE CATCH BASINS AT BOTH ENDS OF BRIDGE WHEN ROADWAY HAS MINIMUM GRADE. CASE C IS UNDESIRABLE. WHERE POSSIBLE ADJUST ROADWAY GRADES TO KEEP THE SAG POINT OFF THE BRIDGE. GENERAL GUIDE FOR USE OF CATCH BASIN AT ENDS OF BRIDGE Figure 7-2.04A
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SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-3(1) 7-3.0 FLEXIBLE PAVEMENT DESIGN 7-3.01 Cross Sections Figure 7-3.01A shows the cross sections for flexible pavements. The thickness design procedures, the widths of the respective pavement layers (bituminous and aggregate base materials) and subsurface drainage details, if needed, are provided in the MnDOT Geotechnical and Pavement Design Manual. BITUMINOUS PAVEMENT DESIGN Figure 7-3.01A (Dual Units)
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SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-4(1) 7-4.0 SHOULDER STRUCTURAL DESIGN 7-4.01 Standard Shoulders Standard shoulder designs for new construction and reconstructed rigid and flexible pavements are shown in Figures 7-4.01A through G. 7-4.02 Widened Pavement Shoulders Figure 7-4.02A shows typical designs for rehabilitating narrow concrete pavement structures. The figure show the respective placement of the required widening and overlay, and shoulder design. The designer should consult with the District Materials/Soils Engineer for recommendations concerning the various pavement materials, thickness, and drainage details to be used in construction of the various pavement structural components. AGGREGATE SURFACED SHOULDERS FOR RIGID PAVEMENT Figure 7-4.01A (Dual Units)
7-4(2) ROAD DESIGN MANUAL SEPTEMBER, 2006 BITUMINOUS SURFACED SHOULDERS FOR RIGID PAVEMENT Figure 7-4.01B (Dual Units)
SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-4(3) CONCRETE SURFACED SHOULDERS FOR RIGID PAVEMENT Figure 7-4.01C (Dual Units)
7-4(4) ROAD DESIGN MANUAL SEPTEMBER, 2006 AGGREGATE SURFACED SHOULDERS BITUMINOUS PAVEMENT WITH AGGREGATE BASE Figure 7-4.01D (Dual Units)
SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-4(5) BITUMINOUS SURFACED SHOULDERS BITUMINOUS PAVEMENT WITH AGGREGATE BASE Figure 7-4.01E (Dual Units)
7-4(6) ROAD DESIGN MANUAL SEPTEMBER, 2006 CONCRETE SURFACED SHOULDERS RIGID PAVEMENT WITH CURB AND GUTTER Figure 7-4.01F (Dual Units)
SEPTEMBER, 2006 ROAD DESIGN MANUAL 7-4(7) BITUMINOUS SURFACED SHOULDERS FLEXIBLE PAVEMENT WITH CURB AND GUTTER Figure 7-4.01G (Dual Units)
7-4(8) ROAD DESIGN MANUAL SEPTEMBER, 2006 WIDENED PAVEMENT SHOULDERS Figure 7-4.02A (Dual Units)