4-39 Section 406. Precast Three-Sided, Arch, and Box Culverts
406.01. Description This work consists of the follow ing:
A.Designing, load rating, fabricating, and constructing precast concrete three-sided, arch, precast concrete box culverts and other precast elements ;
B.Providing dewatering;
C.Maintaining the water flow during construction stages;
D.Providing and installing gaskets , segment anchoring, and geotextile fabric to seal culvert joints ;
E.Designing, fabricating, and constructing connections; and
F.Designing, installing, maintaining, and rem oving associated work including dewatering to maintain flows. 406.02. Materials Provide materials in accordance with the following sections : Cement Type I, Type III ......................................................................... 901 Granular Material Class II, III, IIIA ......................................................... 902 Coarse Aggregate 6A, 6AA, 26A, 17A .................................................. 902 Fine Aggregate 2NS .............................................................................. 902 Open-Graded Aggregate 34R , 46G ..................................................... 902 Concrete Admixtures ............................................................................. 903 Curing Compound ................................................................................. 903 Fly Ash .................................................................................................. 903 Asphaltic Materials ................................................................................ 904 Steel Reinforcement ............................................................................. 905 Structural Steel ..................................................................................... 906 Miscellaneous Metals ............................................................................ 908 Sealers for Culvert Joints ...................................................................... 909 External Rubber Gaskets ...................................................................... 909 Geosynthetics ....................................................................................... 910 Filter Bags ............................................................................................. 910 Sand and Stone Bags ........................................................................... 916 Concrete ............................................................................................. 1004 Mortar, Type R -2 ................................................................................. 1005 Provide natural coarse aggregate for 6A, 6AA, and 17A in accordance with subsection 902.02. Provide aggregate with a gradation meeting Michigan MDOT Standard Specifications for Construction Section 406
4-40 Series 6AA or 17A, the physical requirements of 6AA, and not exceeding the
following nominal maximum size requirements:
A.One-fifth the narrowest dimension between forms ;
B.One-third the depth of slabs ; and
C.Three-quarters the minimum clear spacing between individual reinforcing bars or wires. The freeze-t haw dilation, percent per 100 cycles , must not exceed 0.030 %. Provide steel inserts zinc coated in accordance with ASTM B633 for service condition 4 or a Department -approved equal. Provide epoxy -coated steel in headwalls , wingwalls, apron, curtainwall and collars. Select a precast concrete three-sided or arch culvert from within the categorized types on the Qualified Products List and as shown on the plans . All manufacturers must be certified by the Precast/Prestressed Concrete Institute (PCI), the National Precast Concrete Association (NPCA), or the American Concrete Pipe Association (ACPA). 406.03. Construction
A.Design . Provide a plan for dewatering and/or maintaining stream flow that complies with EGLE permit requirements and MDOT Standard Plans and submit it to the Engineer for review 7 days before the installation of the system.
1.A Professional Engineer licensed in the State of Michigan must seal the design for precast three-sided, arch, box culverts , connections, and other precast elements . Sheeting and cofferdam design must be in accordance with subsection 704.03. Provide culverts with the rise, span, skew angle, and minimum waterway area shown on the plans. Obtain the Engineer ’s approval for larger spans or rises. Submit the design to the Engineer for review and approval at least 14 calendar days prior to fabrication. When HL-93 modified live load is specified, apply HL-93 live load in accordance with the AASHTO LRFD [Load and Resistance Factor Design] Bridge Design Specifications with the following exceptions:
a.Increase the load of each axle of the design truck, shown in Figure 3.6.1.2.2-1 of the AASHTO LRFD Bridge Design Specifications , by 20%;
b.Increase the design lane load, specified in Article 3.6.1.2.4 of the AASHTO LRFD Bridge Design Specifications , by 20% ; and MDOT Standard Specifications for Construction Section 406
4-41 c. Replace the design tandem, specified in Article 3.6.1.2.3 of the
AASHTO LRFD Bridge Design Specifications , with a single 72 kip load. Use a Class 2 exposure condition when satisfying the provisions of Article 5.6.7 in the AASHTO LRFD Bridge Design Specifications .
2.Precast Concrete Three-Sided and Arch Culverts . Design the precast three-sided or arch culvert in accordance with AASHTO LRFD Bridge Design Specifications for HL-93 modified live load and ASTM C1504. Base the design on the loads shown on the plans. Investigate all load factor combinations to produce the positi ve and negative extremes (minimum load factors applied to loads that reduce the force effect being investigated). The design must identify the maximum factored inward and outward horizontal forces and vertical forces at the base of the culvert wall. Perfor m plan modifications, including design, to accommodate the actual precast units being used. The maximum factored horizontal and vertical forces must be less than the horizontal and vertical capacities of the footings, as shown on the plans . Verify that the footing dimensions, including keyway size, and footing concrete compressi ve strength, as shown on the plans, are compatible with the culvert design.
3.Precast Concrete Box Culverts. Design precast box culverts less than 10 feet in span length measured along the centerline of the roadway in accordance with the AASHTO LRFD Bridge Design Specifications and ASTM C1577. As an alternative to the design tables in ASTM C1577, the Contractor may use other refined software programs if approved by the Engineer. Program s to design culverts may be used provided the design includes HL-93 live load without lane load and dynamic load allowance as defined in the AASHTO LRFD Bridge Design Specifications . Design precast box culverts greater than or equal to 10 feet in span length measured along the centerline of the roadway in accordance with the AASHTO LRFD Bridge Design Specifications for HL-93 modified live load . Design joints between adjacent box culvert sections in accordance with Section 8 of ASTM C1577 and to accommodate the joint sealing material in accordance with section 914 as applicable.
4.Precast Concrete Headwalls, Wingwalls, and Aprons. Design headwalls, wingwalls, and aprons in accordance with the AASHTO LRFD Bridge Design Specifications and as specified herein. MDOT Standard Specifications for Construction Section 406
4-42 a. Headwalls. Design headwalls to resist forces due to earth
pressure and vehicle impact in accordance with the contract documents .
b.Wingwalls. Design wingwalls to resist forces due to earth pressures and live loads.
c.Aprons. Coordinate design of aprons with other elements.
5.Connection. Design connections in accordance with the AASHTO LRFD Bridge Design Specifications . Unless otherwise shown on the plans, bolts used in bolted connections must have a diameter of at least ¾ inch. Field-welded connections are not allowed.
B.Load Rating. The load rating must be performed by a Professional Engineer licensed in the State of Michigan.
1.Load Ratin g Procedure . Load rate culverts with a span of at least 10 feet to verify that the culverts can carry legal loads and class A overloads. Measure the span along the centerline of the roadway between inside faces of exterior walls. Perform the load rating using the load and resistance factor rating (LRFR) method in accordance with the AASHTO Manual for Bridge Evaluation, MDOT ’s Bridge Analysis Guide , and MDOT ’s Michigan Structure Inventory and Appraisal Coding Guide. Include a 25- pound- per-square-foot future wearing surface in the load rating. Calculate the following ratings:
a.Federal inventory rating, National Bridge Inventory (NBI) Item 66;
b.Federal operating rating, NBI Item 64;
c.Michigan operating rating, MDOT Item 64M; and
d.Michigan overload class, MDOT Item 193A. If changes are made during construction, update the load rating for the as-constructed conditions and submit the updated load rating documentation to the Engineer. The updated load rating must analyze for both the as -constructed conditions and the as -constructed conditions with placement of future wearing surface. MDOT -directed changes will be paid for as extra work.
2.Load Rating Documentation. Submit the following information to the Engineer in electronic portable document format (PDF) at least 14 days prior to fabrication:
a.Assumption sheet containing a list of assumptions made in the analysis regarding material properties, vehicle configurations, live load factors, live load distribution, and other factors; MDOT Standard Specifications for Construction Section 406
4-43 b. Software calculation input and output;
c.Manual calculations; and
d.A complete Bridge Analysis Summary Form.
C.Working Drawings . Submit working dr awings to the Engineer for review and approval. Do not begin fabrication until receipt of written approval of the working drawings from the Engineer. Include the following in the working drawings:
1.Load ratings using as -designed conditions;
2.Design assumptions;
3.Design loads;
4.Design calculations;
5.Culvert dimensions ;
6.Fabrication methods;
7.Method of joining adjacent culvert elements;
8.The fabricator ’s minimum fill depth required for construction traffic over the culvert ;
9.Compressive strength requirement prior to removal of forms ;
10.Connection details;
11.Dimensions of concrete wingwalls, head walls, curtain walls and aprons;
12.Steel reinforcement lap lengths and development lengths; and
13.Cast-in-place concrete details, including concrete that is paid for separately. Cast-in-place head walls, wingwalls, aprons, and curtain walls may be used as an alternative to precast sections at no additional cost to the Department. Identify deviations from the contract on the working drawings. If deviations are not clearly identified, the Department will not consider the deviations as part of the shop drawing approval.
D.Fabrication . Do not begin fabrication until the Engineer has approved the design, working drawings , and load rating. Do not fabricate box culverts using dry cast methods . MDOT Standard Specifications for Construction Section 406
4-44 1. Placement of Reinforcement . Provide three times the wire diameter,
but not less than 1 inch, of concrete cover for welded wire reinforcement. For the reinforcement in the top of the top slab of culverts covered by less than 2 feet of fill, provide at least 2 inches of concrete cover. Assemble reinforcement using a maximum of three layers of welded wire reinforcement. A single layer of deformed steel reinforcing bars may be used instead of welded wire reinforcement . If using deformed steel reinforcing bars, provide a minimum concrete cover of 2 inches. The ends of the longitudinal reinforcement must be no greater than 2 inches from the ends of the culvert section. Exposure of the ends of longitudinal reinforcement or spacers used to position the reinforcement will not be cause for rejection.
2.Reinforcement Development Length, Splices, and Spacing . Develop the exterior corner reinforcement and splice reinforcement in accordance with the AASHTO LRFD Bridge Design Specifications and ASTM C1577.
3.Joints
a.Precast Three -Sided and Arch Culverts. Provide a 1- by 1-inch or ¾- by ¾ -inch beveled edge on the external surface of the joint formed between the culvert units.
b.Precast Box Culverts. Provide tongue and groove ends in accordance with ASTM C1577. Shop drawings must accurately depict the shape of the tongue and groove configuration. Joint configurations other than what is specified in ASTM C1577 are not acceptable. Box culvert sections installed with joints not meeting ASTM C1577 must be removed and replaced with materials that meet specification at no cost to the Department .
4.Concrete. Proportion and mix cement, aggregate, admixtures, and water to produce a homogeneous concrete that meets the following requirements. Unless otherwise shown on the plans, the precast culvert manufacturer is responsible for the concrete mix design with 28-day compressive strength of at least 5, 000 psi, containing 5.5 to 8.5% entrained air and maximum slump of 4 inches. If Type F or Type G admixtures are used, the Department will allow a maximum slump of 7 inches. Place concrete to avoid material segregation and reinforcement displacement. Do not allow concrete to free fall mo re than 12 inches to the top of the forms. MDOT Standard Specifications for Construction Section 406
4-45 Provide internal vibrators capable of visibly affecting the mixture for at
least 18 inches from the vibrator. Use mechanical, high- amplitude internal/external vibrators to consolidate the concrete during and immed iately after placement . If using epoxy -coated or other coated reinforcement, use a vibrator with a rubber -coated head. Move vibrators to prevent forming localized areas of grout. Uniformly space the points of vibration no greater than twice the radius over the visibly effective vibration area. Do not hold internal vibrators against forms or reinforcing steel, and do not use them for flowing or spreading concrete. Do not disturb partially hardened concrete. Maintain forms, reinforcing steel, and placing equi pment clean and free of hardened concrete. Do not disturb forms or projecting reinforcement after the initial set of the concrete. If concreting operations extend into the night, light the work area to make operations visible for inspection. Hand methods for concrete consolidation will be allowed if the Engineer determines that vibratory methods are not possible. Immediately after removing forms, patch air holes larger than ¾ inch diameter and ⅜ inch deep with Type R -2 mortar as directed by the Engineer.
5.General . Construct mortar -tight forms with net sections capable of withstanding impacts during placement and or supporting the weight of concrete through curing. Use removable forms in accordance with subsection 706.03.D.3, except that Type B surfaces are not allowed.
6.Curing. Use one or a combination of the following curing methods:
a.Low pressure steam -cure the culvert sections in accordance with subsection 708.03. C.11.
b.Water cure the culvert sections using methods that maintain continuous moisture on the sections for at least 7 days.
c.Accelerate overnight curing using an external heat source while minimizing moisture loss from exposed surfaces. Apply the initial heating 2 hours aft er final concrete placement.
d.Apply a sealing membrane that conforms to ASTM C309.
e.Apply a curing compound in accordance with subsection 706.03.N.1. MDOT Standard Specifications for Construction Section 406
4-46 7. Handling . Handle the precast units using a method approved by the
fabricator and Engineer. Do not drill hol es for handling the precast unit. Fill handling holes using one of the following methods before placing backfill:
a.Fill holes with Type R -2 mortar ;
b.Fill tapered holes with concrete plugs, and secure with Type R-2 mortar or other approved adhesives ; or
c.Fill holes with neoprene plugs, wedged tightly to elimi nate annular space. Cover the filled holes with an external grade rubber gasket at least 9 inches by 9 inches , conforming to ASTM C877 or C990, centered over the hole. Use a primer compatible with the rubber gasket to secure the gasket. Install the gasket in accordance with the manufacturer ’s recommendations. Cover the gasket with a 24- by 24-inch geotextile blanket centered over the gasket .
8.Product Marking. Use a method approved by the Engineer to mark the interior of each precast unit with the following information:
a.Span and rise ;
b.Date of fabrication;
c.Name or trademark of the fabricator; and
d.Design earth cover.
9.Steel Reinforcement . Store, protect, handle, field bend, lap, cut , and repai r reinforcement in accordance with subsection 706.03.E except as required below. Place and firmly secure steel reinforcement during concrete placement. Ensure that steel reinforcement is free of dirt and excessive rust, loose mill scale, and other deleter ious material when placed. Do not vary bar spacing by more than one-sixth of the spacing shown on the plans, except as needed to allow placing anchor bolts and position dowels. Use wire ties to secure bar intersections for the top mat and other mats where the product of the length and width of bar intersection spacing exceeds 120 square inches. If the product of the length and the width of spacing does not exceed 120 square inches, tie alternate intersections. Do not weld. Tie bar laps near each end of the lap. Provide a clear distance from the reinforcement to the concrete surface at least equal to the MDOT Standard Specifications for Construction Section 406
4-47 dimensions shown on the plans but no more than 25% of the
dimension. Maintain the required reinforcement distances from forms using stays, ties, hangers, bar chairs, or other Department -approved supports. If bar chairs are used, they must be plastic or coated metal with a bearing area that prevents penetration into forming material.
10.Cold Weather Precautions . Meet the requirements of subsection 706.03.J exc ept as specified by the designer and the following: If the National Weather Service forecasts air temperatures below 20°F during the curing period, provide material and heating equipment on the project to protect forms and concrete. Do not place concrete i f the air temperature is below 40°F unless form interiors, metal surfaces, and the adjacent concrete surfaces are preheated to at least 40°F. Use only gas -fired burners if heating by direct flame. Do not begin placing concrete if the air temperature is below 35°F unless a cold weather QC plan has been approved by the Engineer . Insulating the bottom of forms is not required. If the National Weather Service forecasts air temperatures below 40°F for more than 8 consecutive hours during the curing period, protect the top of the freshly cast concrete as soon as possible to maintain a concrete temperature of at least 40°F. Use tightly joined insulating blankets or polystyrene insulation and insulate in accordance with Table 706-1. Hang tarpaulins or other Department -approved material from the top of the concrete to enclose the entire protected section. If the temperature falls below 15°F during the curing period, circulate heated air under the enclosed superstructure section. Maintain circulation for the remainder of the protection period required for concrete protected by heating and housing.
E.Tolerances
1.Internal Dimensions. Fabricate precast elements so the internal dimensions do not vary from the design dimensions by more than 2 inches. For culverts with haunches, do not vary haunch dimensions by more than ¾ inch from the dimensions shown on the shop drawings.
2.Slab and Wall Thickness. Fabricate precast elements so the slab and wall thicknesses do not vary from the dimensions shown on the shop drawings by more than 5 % or ½ inch, whichever is greater. Slabs and walls thicker than the required dimension will not be cause for MDOT Standard Specifications for Construction Section 406
4-48 rejection unless, in the opinion of the Engineer, the thickness variation
prevents joint sealing.
3.Length of Opposite Su rfaces. Fabricate precast elements so the laying lengths of two opposite culvert section surfaces do not vary by more than 1 inch.
4.Length of Section. Fabricate precast elements so the underrun from the required length measures no greater than ½ inch.
5.Posit ion of Reinforcement. Position reinforcement within ½ inch of the dimension shown on the shop drawings .
F.Testing and Inspection
1.Testing. Test the concrete for compressive strength in accordance with Section 1 1 of ASTM C1504 for precast three-sided and arch culverts and Section 1 0 of ASTM C1577 for precast box culverts.
2.Workmanship, Finish and Appearance. Provide a smooth finish on the culvert surfaces, free of fractures.
3.Repairs. Repair fabrication imperfectio ns, handling damage, or construction damage to culverts as approved by the Engineer, in accordance with section 712, and at no additional cost to the Department.
4.Rejection. The Engineer may reject precast three-sided, arch, and box culverts due to the foll owing:
a.Defects that indicate imperfect proportioning, mixing, or forming;
b.Honeycombed or open textured surfaces that would adversely affect the function of the box or bridge sections ;
c.Damaged ends preventing required joint construction;
d.Concrete that does not attain the required compressive strength;
e.Out of tolerance dimensions;
f.Low or high air content; and
g.Exposed reinforcing steel.
5.Quality Assurance. For culvert spans greater than 10 feet, provide the Department access to perform quality assurance inspection. Notify the Engineer at least 2 weeks before beginning fabrication. The Department does not consider this inspection a substitute for the fabricator ’s QC requirements. MDOT Standard Specifications for Construction Section 406
4-49 G. Installation
1.General . Construct the wingwalls, headwalls, and aprons for precast concrete culverts with a positive connection to the adjoining precast section as shown on approved working drawings. Remove spurs, fins, and excess concrete at joints without spalling. Fit joint to joint without excessive force to prevent damage. Lay the culvert sections in stages to coincide with maintaining traffic, dewatering, temporary pumping, and part width phased construction sequencing and as approved by the Engineer. Cast-in-place wingwalls, headwalls, and aprons may be used as alternatives to precast wingwalls, headwalls, and aprons. Attach cast-in-place wingwalls or headwalls as shown on the drawings approved by the Engineer . Place backfill in accordance with subsection 206.03. Place and compact backfill on opposite sides of the cul vert at the same time so backfill levels on opposite sides do not differ by more than 2 feet. Hand compact backfill within 1 foot of the structure. Use vibratory compactors meeting the culvert fabricator ’s specifications. Install sheeting in accordance wit h subsection 704.03.B. The Contractor is responsible for construction traffic on the culvert.
2.Precast Three -Sided and Arch Culverts . Construct the footing from cast-in-place concrete in accordance with the contract. Construct the footing keyway level to minimize the height of the shims for leveling the precast sections. The Engineer may approve alternate procedures that provide a uniform bed of Type R -2 mortar under the culvert sections. Before placing the culvert sections onto the footing, survey the sur face of the keyway and locate the high spot. Use the high spot as the control elevation for the bottom of the culvert sections. Add 1 inch to the high spot and place shims to that elevation. Use shims that are not susceptible to corrosion. Maintain the elevation of the culvert until the mortar surrounding the shims cures. Set the shims 12 inches from each corner of the culvert sections. If installing the culvert sections on a sloping grade, establish elevation control points at 50-foot increments and run a string line between these elevations to set other shims. Provide joints no greater than 1 inch wide. After placing the culvert sections, grout underneath the culvert leg sections and to the tops of the sides of the keyway with Type R -2 mortar. Grout by mounding the mortar on one side of the leg MDOT Standard Specifications for Construction Section 406
4-50 and vibrating until it passes through to the other side of the leg. If
mortar does not pass through the leg, repeat the process on the other side. Before sealing joints between adjacent culvert sections, provide smoo th surfaces, free of debris. If using cast -in-place headwalls or wingwalls, seal the joints between the culvert elements and headwalls and the joints between headwalls and wingwalls. Make the joints watertight. If using precast headwalls or wingwalls, seal the joints between the culvert elements and headwalls and the joints between headwalls and wingwalls . Make the joints watertight using the same method for joints between adjacent culvert sections. Seal the joints between the adjacent precast culvert secti ons using a ⅞-inch by 1⅜ -inch butyl rope conforming to ASTM C990. Place the butyl rope between the units in the bevel. If the fabricator recommends sealing joints using non-shrink grout and if approved by the Engineer, the Contractor may omit the butyl rope. Cover the butyl rope with an external type rubber gasket at least 9 inches wide, conforming to ASTM C877, centered over the joint. Use a primer compatible with the rubber gasket to secure the gasket. Install the gasket in accordance with the fabricator ’s recommendations . After placement of the gasket, treat every precast concrete exterior joint with cold applied culvert joint sealer and w rap all culvert joints with geotextile blanket regardless of culvert size and material type. The geotextile blanket must be at least 36 inches wide and installed on the culvert exterior, centered on the joint. The ends of the geotextile blanket must overlap by at least 12 inches. Make the completed joint watertight. The joint will be considered watertight if no visible signs of leakage appear around the joint for the duration of the project. If the joint is not watertight, create a watertight seal at no additional cost to the Department. If limited spacing between culvert legs of adjacent spans of multiple span structures prevents sealing culvert leg joints for adjacent spans, use self -compacting engineered fill to prevent leakage of fill through joints. Prevent mi gration of fines through the engineered fill.
3.Box Culverts. Unless otherwise shown on the plans, c onstruct culvert bedding for box culvert s by placing a 9-inch- thick layer of coarse aggregate 6A, with 80% minimum crushed material, or 46G aggregate, covered with a 3-inch-thick layer of 34G, 34R, 26A aggregate, or approved equal. Before placing the 3 -inch-thick layer , MDOT Standard Specifications for Construction Section 406
4-51 compact the 9 -inch-thick layer using at least three passes of a
vibrating plate compactor. Compact the 3 -inch -thick layer using at least one pass of a vibrating plate compactor. If unstable soil conditions or obstructions other than rock require excavation of the trench below the elevation shown on the plans, undercut, backfill, and compact the trench as directed by the Engineer. Use Class 6A, 17A, or 46G aggregate as backfill material for undercutting. Install a gasket in the joint between the box c ulvert sections during placement using closed -cell butyl rubber extrusion type gaskets in accordance with ASTM C990. Use the gasket sizes and instal lation methods recommended by the manufacturer and approved by the Engineer. After installing all box culvert sections, cover the exposed portion of the assembled box culvert joints with a nominal 12-inch-wide external rubber gasket strip centered over the joint meeting the requirements of ASTM C877. Use a primer compatible with the rubber gasket to secure the gasket. Install the gasket in accordance with the manufacturer ’s recommendations . After placement of the gasket, treat every precast concrete box cul vert exterior joint with cold applied culvert joint sealer and cover with a 24-inch-wide strip of geotextile blanket centered on the joint. Make completed joints watertight. The Engineer will consider the joint watertight if no visible signs of leakage app ear from the joint for the duration of the project. If the joint is not watertight, create a watertight seal at no additional cost to the Department. 406.04. Measurement and Payment Pay Item Pay Unit Culv, Precast Three-Sided or Arch, (span) foot by (rise) foot ............ Foot Culv, Precast Conc Box, (span) foot by (rise) foot ............................. Foot Culv Bedding, Box Culv .......................................................... Cubic Yard
A.Precast Three -Sided or Arch Culvert . The Engineer will measure Culv, Precast Three -Sided or Arch along the centerline of the structure. The Department will pay for Culv, Precast Three -Sided or Arch of the type required, in accordance with the span-rise combination shown on the plans. The unit price for Culv, Precast Three -Side d or Arch includes the following:
1.Designing, fabricat ing, load rating, and installing precast elements;
2.Headwalls and wingwalls, whether precast or cast -in-place;
3.Providing and placing shims to level the precast elements;
4.Type R -2 mortar; MDOT Standard Specifications for Construction Section 406
4-52 5. Joint sealer materials;
6.Inserts for bars and connection hardware;
7.Required geotextile blanket;
8.Dewatering and maintaining the stream flow during construction stages; and
9.Providing plan modifications including design, additional plan quantities, and pay items to accommodate any changes to the precast units as shown on the plans. The Department will pay for Culv, Precast Three-Sided or Arch by plan quantity in accordance with subsection 109.01.A . The Department will pay separately f or cast -in-place concrete, other than for culvert segments, wingwalls, and headwalls . Excavation and providing and placing backfill material, including engineered fill between adjacent spans and drainage materials , will be paid for by plan quantity in accordance with subsection 109.01.A. The substructure design is specific to the three-sided or arch culvert detailed on the plans. The Contractor must use approved MDOT service vendors qualified in h ydraulics, geotechnical engineering services, and short - and medium -span bridges to perform the required design and plan modifications, as directed by the Engineer, if the Contractor selects a culvert shape different than shown on the plans.
B.Box Culvert . The Engineer will measure Culv, Precast Conc Box along the centerline of the structure. The Department will pay for Culv, Precast Conc Box of the span-rise combination shown on the plans. The unit price for Culv, Precast Conc Box includes the cost of the following:
1.Designing, fabricat ing, load rating, and installing the precast elements;
2.Headwalls and wingwalls, whether precast or cast -in-place;
3.Aprons and curtain walls, whether precast or cast -in-place;
4.Joint sealer materials ;
5.Geotextile blanket for box culvert joints;
6.Inserts for bars a nd connection hardware; and
7.Dewatering and maintaining the stream flow during construction stages. The Department will pay separately for cast -in-place concrete, other than for culvert segments, wingwalls , and headwalls . Excavation and providing MDOT Standard Specifications for Construction Section 406
4-53 and placing backfill material will be paid for by plan quantity in accordance
with subsection 109.01.A .
C.Culvert Bedding, Box Culvert. The Engineer will measure Culv Bedding, Box Culv by volume compacted in place to the depth, length, and width shown on the plans or as directed by the Engineer. The unit price for Culv Bedding, Box Culv includes placement and compaction of the coarse aggregate 6A and open-graded aggregate 34R or 46G, or other materials as shown on the plans or approved by the Engineer .
D.Rock Excavation. The Engineer will measure and the Department will pay separately for ro ck excavation in accordance with subsection 205.04.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 245–259 of 1,146.