Pavement sags and rough areas may require a wedging course. The top size of the top scalping screen shall be 1.5 for top and leveling courses and 2 for base courses. The gates move vertically, either manually or mechanically. Loads that have become contaminated because of spilled gasoline, kerosene, oil and the like, should not be used in the roadway. If a hydraulically extendable screed is being used with the paver, the crown can be introduced in the center of the main screed and also at the points between the main screed and the hydraulic extensions. 0PpdR7Lof Care should be taken to avoid overheating, which can cause permanent warping of the screed. Projects constructed under a warranty special provision still require inspection staffing and complete documentation prior to payment, including MDOT materials certifications, MDOT yield checks, MDOT quantity measurement, and MDOT Inspectors Daily Reports. Pavers spread the hot mix asphalt to the desired width and thickness and produce a smooth, uniform mat texture. It is good practice to keep the speed of the paver as constant as possible during the paving operations. Depending on the material and job conditions, this can be quite dramatic. The elevation of a fresh mat in relation to the base. A slight change in direction, or curl, is beneficial at each reversal spot to further reduce the tendency of the mix to shove under the compactor and to eliminate the possibility of a bump at the point where the roller reversal occurs. The typical equipment used: Used for cleaning the old surface to be paved. Ensure existing surface failures are repaired properly. These adjustments may be allowed if there is reason for the request and as long as the resulting mixture meets the specifications for the project. For relatively thin layers of mix, generally less than 1-1/2 inch, the vibratory roller should typically be operated in the static mode. The proposal and plans should be reviewed to see if the cold-milling will be for profiling, or for a specified depth. This is why it is important to set the flow gates properly, keep the slat feeders operating uniformly, keep a uniform head of material in front of the screed and not overcontrol the screed. This skirt will help keep the tires hot by holding the heat from the mix under the roller. MDOT has ongoing government-to-government communication with 12 federally recognized sovereign tribal governments whose lands are situated within Michigan. The inspector should mark areas that will require wedging, which will usually occur when the existing pavement has depressions of 1 inch or more. A new plant inspector can easily get burned if not aware that asphalt samples are very hot. All roller marks should be removed by the finish roller. Is distributor tachometer working properly? These asphalt cements may also contain anti-strip agents. The distance the screed of the trailing paver should extend over the uncompacted mat behind the first paver should be limited to no more than 1 inch. MDOT provides funding for competitive grant and loan programs primarily, but not exclusively, for state and local road agencies for the greatest impact on economic development and job creation. The last meter of the HMA material should be raked and all the large stones removed, leaving the fine material. You may also contact Ryan Doyle at DoyleR3@Michigan.gov. HMA mixtures consist of a blend of asphalt binder and aggregates mixed in an asphalt plant. Are roller wheels free of openings or projections? In addition to the longitudinal mark, a mismatch in the elevation between the two screeds can also result in a possible difference in surface texture. These adjustments should be completed within the first two loads placed. Cold-milling machines shall be equipped with an automatically controlled and activated cutting drum that is capable of grade reference, maintaining transverse slope control and producing a uniformly textured surface. Fat spots can be caused by high moisture in the mixture; if the mixture is very hot, asphalt could run down to the bottom of the truck during transport and cause fat spots when dumped into the paver. The street inspector can easily get hurt if they are not aware of the number of vehicles operating on the paving site. Steam rising from the mix as it is dumped into the hopper of the spreader indicates moisture in the mix. After the paver placing the top course has passed over the structure and the hand raking and shaping have been completed, it may be necessary to compact this area by the hand tamper method. If it falls at the free edge of the pavement, the core location should be moved 2 inches in from the edge. Three types of self-propelled rollers are currently being used: static steel wheel, pneumatic tire rollers and vibratory rollers. The MDOT plant inspector should follow the sampling and testing procedures explained in the Special Provision 20SP501(R) Superpave Hot Mix Asphalt Percent Within Limits (PWL) or 20SP501(S) Superpave Hot Mix Asphalt Percent Within Limits (PWL) For Capital Preventive Maintenance (CPM) Mill & Resurface Projects and CPM One Course Overlay Projects. Does the paver have two operating warning lights? Worauf Sie als Kunde bei der Auswahl der Nici qid achten sollten. Resources regarding MDOT's contracting processes, including contractor prequalification, bid letting, contract awards, and contractor payments. The screed extensions should be level with the main screed. Any severely spalled areas at joints should be repaired using partial-depth repair methods. This is helpful at lane tapers, crown corrections, or in areas of wedging. The tire surface must be kept hot to reduce the pick up of fines from the mixture being compacted. It is also possible to require the Contractor to remove a sublot of leveling course mixture that has already had the top course mixture placed upon it. Before placing any HMA patch, the area to be patched must be cleaned and a bond coat applied. The tapered longitudinal joint shall be constructed by tapering the HMA mat; the taper shall have a 1 to 12 rise and the taper shall extend beyond the normal lane width. Public Notice of Metro Region Bridge Council Meeting for September 28, 2022 Resources for local governmental agencies that regularly require access to state right of way. Yield = 93920 pounds/561.33 square yards= 167.3 lbs/square yard. See Figure 502-3. The tiers identified below apply to Superpave Thus, the amount of mixture that can be carried back to the augers on one side can be different from the other side. Ensure the bond coat has been applied uniformly at the proper yield. Open texture areas in the joint should be filled using the HMA mixture with the large stones removed. It covers all or parts of 13 states in the US and five provinces or territories in Canada. This is true for both the Project Engineer and his staff and for the Contractors general superintendent, plant and paving superintendents and all foremen. Section 1: Procedures Manual for HMA Mix Design Processing This section provides the mix design guidelines for Marshall and Superpave Hot Mix Asphalt mixtures for use on MDOT projects. Staff oversight should be at a level to assure compliance with contract specifications and to properly assure the quality of the constructed work. @c0M8;\ r)]-f3E|r ZVu~[ The hauling unit must be capable of completely protecting the mixture from the weather and ensuring that the mixture temperature is maintained during the hauling time. Keep the level of mix in the hopper above the flow gates. The auger and the slat conveyor on the same side must be operated together. Transportation Grant Programs, Letting Process, Local vs. MDOT for Enhancement Projects, Heidi Spangler, Safety Engineer, 517-230-4605, FY 2024 Local Safety Program Applications Received Roller passes must be distributed uniformly over the width and length of the area being compacted. However, if the project does not call for HMA mixtures, or the patching is in advance of the paving operation, any mixture readily available and approved by the Engineer can be used. Load ticket = 46.96 tons x 2000 pounds per ton= 93920 pounds, Area Covered: 421 feet x 12 feet wide/9 sft/syd = 561.33 square yards. If the random core location falls over a tapered joint, it should be moved to the first point that the mat is full depth. Excess Moisture. Trying to reconstruct events at a later time without written notes and complete test data is usually frustrating and often results in conflicting opinions as to exactly what happened. Slow and steady is the key to good vibratory compaction procedures. The top course will then be placed at a uniform rate. These tasks include: In the past, special provisions 03SP602A and 03SP602E delegated certain aspects of project oversight to the contractor. All things related to pavement engineering. The HMA mixture used for patching should be the top course mixture called for on the plans, or in the proposal. A. Rollers can also be a combination of both pneumatic and steel wheel. Unsere Bestenliste Jan/2023 Detaillierter Produktratgeber TOP Grey goos vodka Aktuelle Angebote Vergleichssieger Direkt weiterlesen. If two pavers running in echelon are used, the construction of the joint is similar to the building of a joint against a cold compacted pavement. Do extensions have proper vibratory action? Qualifications of material sampling technicians. Hot Mix Asphalt Selection Guidelines Revised: 03/10/2020 FHWA Approved: 05/07/2020 The following guidelines have been developed at the request of Local Agency Engineers for use on Local Agency projects. These devices are used to carry the mixture from the hopper through the paver tunnel to the back of the paver and the spreading augers. Samples shall be taken if visual observations show significant variations in existing pavement mat. Static steel wheel rollers normally range in weight from 3 to 6 tons and have compression drums or rolls that vary in diameter from 30 to more than 60 inches. MDOT has seven region offices and several geographically located Transportation Service Centers (TSCs) in each region that handle transportation-related construction and maintenance programs. If the automatic controls are being used, the screed operator should not try to change the screed manually by turning the thickness control crank. This certification includes the approval of the field laboratory used for acceptance testing, the Contractors quality control plans (which should be available at the plant) and other plant operational requirements. The MST time zone is the least populated time zone in the USA. Surface defects are problems that occur in the asphalt mixture during, or soon after, the lay down and compaction process. These guidelines provide for the selection of Hot Mixed Asphalt (HMA) and application rates utilizing the Superpave mix design system along with the Marshall Mix design system. Hand tools, level, straightedge and boards. . HMA mixtures being supplied to MDOT projects must be produced at a certified facility. icPUBJ FP rM4"d_`Sx".HCaM;)v}khmqj*KDRu`JK*l*fiEpg[`+H9g@ Ct)L;9BnLjvJdQP7BHD#},i-7D4lPNy`B_]Z)Hg BWPl!3I8"#wQjBANtNV #P9!#)C6.q]BX9#mCw MDOT provides technologies and partnerships in order to make the transportation system safer and less congested. Did the paver have to stop and wait for trucks? This mark can easily be eliminated by adjusting the elevation of the extendable screed in relation to the main screed. The roller pattern should be set up as soon as paving starts. Does paver have properly working screed heaters? Another texture problem that may be observed is caused by material segregation. Because continuity of the asphalt paving operation is critical to providing a quality pavement, the discussion between MDOT and the Contractor personnel should include such items as those listed below. 4649 0 obj <]>>stream Only enough bond coat should be applied that can be covered the same day. It is not required to have a stockpile with enough material to produce the recycled mixtures approved for the project. The discussion should include the safety of those individuals working on the project, as well as the safety of the traveling public. The weigh bridges on the cold feed and RAP charging conveyors must be calibrated. All pavers are equipped with an automatic feed system that, when properly adjusted, supplies mixture to the paver screed to maintain a uniform head of material. When such changes do occur, it is important that they be communicated between the Contractor and MDOT and between MDOT and the Contractor. The old saying Safety is Everyones Business is certainly true on an HMA paving project. A paving schedule for the project should be presented and discussed with MDOT. The function of the hot mix plant is to heat the aggregates, add the asphalt cement and produce a homogenous asphalt mixture. This is caused by an improperly adjusted screed angle of attack. This 55 foot overall length assembly produces a mat with an exceptionally smooth riding surface. The rollers vibratory frequency should match its travel speed. 309 0 obj <> endobj After production begins, the Contractor may ask for JMF adjustments. This check is done by roughly measuring the area covered by one truckload; the tonnage placed is known from the load ticket. To reach the required density, the quickest initial compaction should occur directly behind the lay down machine. Selection of appropriate pavement marking materials (paint, thermoplastic . After curing, only traffic essential in the work should be allowed on the bond coat. `qr`@UtT! u#$$mB3B2(&qiB[g%R(ck7H,D"-Vg#Y All existing pavements, including newly-constructed HMA widening, which are to be surfaced, should receive a bond coat application. In general, the vibrators should be used near the maximum possible frequency. Test methods to be used should be reviewed to assure that individuals understand the purpose of each test, the location of the field lab and the personnel who are to conduct the tests, the time frame for the communication of the test results and the procedures to be used if failing test results are obtained. If the wedging is greater than 3 inches, two courses of HMA mixture may be required. Old patches that show signs of instability, areas with excess asphalt, or excess crack filler, and areas with loose material should be removed and repaired. The batch plant consists of the cold feed system, individual bins that hold and feed the aggregate to the drum dryer (Figure 501 3). In Michigan, there are three publicly-owned and operated bridges: Mackinac Bridge, Blue Water Bridge, and International Bridge. Providing the highest quality integrated transportation services for economic benefit and improved quality of life. Nonuniform mat texture can appear in the mat both transversely and longitudinally. Ride Specification provides guidance to using the Pavement Surface Profile. This will happen on windy days and when the mat thickness is thin, normally the wearing course. All HMA lifts shall be placed, compacted, and allowed to cool to at least 130F, or cool enough to support construction equipment without visible distortion or distress of the mat prior to placing any subsequent HMA layers. Fuel oil is not permitted for use on tapered joint rollers and mobile mat reference wheels. The next truck should then be backed toward the paver, stopping short of the paver. MDOT's A/E internal guidelines, and federal laws and regulations. The Veteran Internship Program assists honorably discharged veterans of the United States Armed Forces as they transition into the civilian workforce. Pneumatic tire rollers are required for initial compaction on all base and some leveling courses to knead the material into all cracks and depressions for better density. FY 2024 Safety (HSIP and HRRR) Call Letter The HMA mixture shall be provided to meet the requirements of the current Michigan Department of Transportation(MDOT) 2020 Standard Specifications for Construction except where modified herein. %PDF-1.7 The aggregates are then proportioned by weight into the mixer, also called the pug mill. Whenever the temperature of the previously placed mats falls below 170F prior to placement of the adjacent mat, or when placing base mix and the air temperature is below 50F, the vertical edges of the initial mat shall be coated with HMA bond coat material before the mixture is placed in the adjacent section. The people most likely to be hurt on an asphalt paving project are those individuals who are new to this type of work. Paving done with automatic screed controls is accomplished with a combination of grade control on one side of the paver and slope control to determine the grade on the other side of the paver. The HBCU TDRP is a unique partnership between MDOT and Michigan colleges and universities to offer on-the-job training to undergraduate students pursuing degrees in engineering or transportation-related careers. Federal-Aid Highways Environmental Efforts It is the Contractors responsibility to ensure that the mixture temperature is adequate for placement and compaction; however, if the inspector observes mixture that is either too cold or too hot, the problem should be pointed out to the Contractor and the Engineer. 30 to 120 m 3 /h; EBA Mobile plant for medium productions. Drum mixers come in many different types, such as parallel flow, counter flow, double barrel, drum-within-a-drum and drums with separate mixing chambers (Figure 501-4). Common Safety Countermeasures for Local Agencies for Segments and Intersections }szvn?w -L7C#qV_?[tp}Ts E[3M;oW|90}!v$z3* It is MDOTs responsibility to conduct quality assurance and verification sampling and testing to ensure conformity of the mix to 20SP501(R) Superpave Hot Mix Asphalt Percent Within Limits (PWL) or 20SP501(S) Superpave Hot Mix Asphalt Percent Within Limits (PWL) For Capital Preventive Maintenance (CPM) Mill & Resurface Projects and CPM One Course Overlay Projects.This testing is done at the field laboratory provided by the Contractor located at the asphalt plant or at an MDOT Region Lab. This process is typically used for superelevation corrections, placing a wedging course so that the leveling and top courses can be placed at a uniform thickness. It is also the responsibility of MDOT and the Contractor to discuss any unusual aspects of the project, items that are not routine construction practices. The second unit is the paver screed. . All the tires should be the same size, ply and tire pressure. When the paver starts, go to paving speed as fast as possible. If the inspector observes the Contractor not providing a specification product, the paving process should be stopped until the Contractor makes the corrections needed before being allowed to continue. A superstructure that spans the screed and auger areas ties the two together and supports the grade sensor. This article returns the responsibility for these tasks to MDOT for all concrete paving projects, including those that contain special provisions 03SP602A and/or 03SP602E. This unit is responsible for the development of statewide processes for the implementation of all required state and federal regulations as it relates to local agencies. <>/Metadata 445 0 R/ViewerPreferences 446 0 R>> This allows the paver operator to feed more or less mixture to either side of the paver. 2.5 HMA or WMA, HT (19 mm MIXTURE) Polymer Modified (1 @ 2.5) 3 HMA or WMA, HT (19 mm MIXTURE) (1 @ 3) 6 Lime Fly Ash Treated Granular Material (9/C) 13.5 Structure Thickness 6 Chemically Treated Subgrade 7 Shoulder Granular Material (5/C) Multiple lifts of 9.5 mm HMA/WMA should be avoided. This equipment must be capable of accurately removing the pavement surface, in one or more passes, to the required grade or cross section. MDOT Microstation Workspace Instructions, Asset Management Guide for Local Agency Bridges in Michigan Stopping the paver and allowing the screed to settle into the mat. The rolling zone should be kept as short as possible. Determine the length of one pavement representing a sublot of material, the width of the pavement and the number of samples, (n), needed for each sublot. % Thus, the samples will be taken at 1985 and 6.3 feet from the beginning of the pavement. xc```f`` Compaction must be achieved while the stiffness of the mix is low enough to allow for reorientation of the aggregate particles under the action of the rollers. When the inspector sees an improper bond coat application, the operation should be stopped. Stop the paver at this point, remove it from the roadway and remove any excess HMA material from the roadway. In this instance, the two numbers chosen were: 0.376 and 0.529, for length and transverse offset. Once these forms are complete, all pertinent information needs to be entered into the Statewide Warranty Administration Database (SWAD) and letters sent directly to the contractor and directly to the Surety Company notifying them of the results of the inspection and status of the warranty prior to the expiration date. Shoulder samples shall be taken if RAP from shoulder is to be used. The web Browser you are currently using is unsupported, and some features of this site may not work as intended. If this yield is found to be high or low from that specified on the plans, a slight adjustment of the thickness controls should be made and the yield rechecked. 4 0 obj Rocking slabs must be stabilized. Profiling is used to establish a new cross section in the existing pavement. Figure 502-11 illustrates the wedging process. One side of the paver is controlled by the grade referencing sensor and the other side is controlled by the slope controller. A rule of thumb is that the proper level of air voids should be obtained before the mixture cools to a temperature of 176F. This section provides the mix design guidelines for Marshall and Superpave HMA mixtures for use on MDOT projects. When slope control is used, the thickness of the mat on the side of the paver that is controlled by the slope sensor could be variable, depending upon the condition of the existing surface. Multiple drops of the mix are necessary. To convert the yield to mat thickness, the following will be helpful: 110 pounds/square yard = 1 inch of thickness. Risk analysis is specifically used to select appropriate performance standards for various bridge . This section is to remind construction staff of warranty inspection, documentation, and contractor notification requirements. Please contact your LAP staff engineer with any questions. Resources for specialized engineering and technical support for construction staff across Michigan. A listing of key Contractor personnel who will be assigned to the project, with clear lines of authority, should be provided to MDOT. The asphalt cement in the storage tanks should be kept at a constant temperature, normally between 275F and 311F . 316 0 obj <<1cc850f8a7a5b5157c73556bf669a59d>]>>stream The paver consists of two primary parts, the tractor unit and the screed unit. This special provision applies to all Hot Mix Asphalt (HMA) acceptance testing for all Road Commission for Oakland County (RCOC) roads. Before overlaying the old pavement, it should be inspected. The JMF is prepared and signed by the TMI. Qualification of the material sampling technicians should be a pre-production meeting agenda item. Sampling methods and frequencies should be discussed. Document when immediate possession of the extracted cores occurs (core ID, date, time, etc.). Trim the joint at right angles to the roadway centerline. On structures in the curb line out of the traveled roadway, the top of the cover should be 3/8 inch (8 mm) below the wearing surface after final compaction is completed. {7:r!> -)t=:NuL5oqba5q]oe`0jC Paver speed is a large contributor to the smoothness of the ride on a finished pavement. Document the taking of loose mix samples from behind the paver. Long and short waves can be caused by a fluctuating head of material in front of the screed. Bleeding can be caused by too much asphalt cement in the mixture, or by allowing traffic onto the paved surface before the surface has cooled sufficiently. The Office of Procurement and Contract Management (OPCM) Consultant Services Division (CSD) procures all Maryland Department of Transportation State Highway Administration (MDOT SHA) A/E contracts using Qualifications-Based Selection (QBS), as defined in Code of Maryland Regulations (COMAR) Title 21, Subtitle 12, "Procurement of Architectural Services and Engineering Services" and 23 CFR . 80 to 150 m 3 /h See Figure 502-6. The office also works directly with legislators' offices regarding state and local transportation constituent concerns. This type rollers compactive effort is a function of the wheel load, the tire pressure, the tire design and the depth of penetration of the tires into the mix. While the paver is operating, laborers may work, or rework, a portion of the mix to fit the paving around objects and to fill in areas that the paver does not pave adequately, or cannot reach. Transportation Reality Check takes on some of these myths, and explains why MDOT does things the way they do. It may be bubbling or popping as if it were boiling. Care should be taken to neatly construct the joint at a right angle to the centerline of the roadway. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> 2022 Selected Projects for FY 2025 Item 340 is generally not recommended for projects with more than 5,000 tons of HMA. ~zWRGO#wnpOs1`(yvM>.D>N^-E*na71K7L.E5! One of the greatest contributors to a poor ride on an urban project is the improper adjustment of manholes. DZs}9{,dp ^E3 `E%)eNDL-F1>tcf^cs\3WCwn}YI.kaz1r LX[t6*4u*QEI^:RG3iiv=I ->6{mU=CKGuK'b Asphalt paving projects, like many construction projects, are not always built as originally scheduled. 4.4 MDOT Standard Practice for Random Sampling of HMA Materials 4.4.1 Sampling In-Place Paving Material 4.5 Utilizing Reclaimed Asphalt Pavement (RAP) Millings from the Same Project When Using a Portable Hot Mix Asphalt (HMA) Plant GENERAL Pre-Production Meeting A pre-production meeting should be held before work commences on a project. Too Hot: Blue smoke rising from the mix usually indicates an overheated truckload. If a hydraulically extendable screed is to be used at a fixed width for a period of time, the paver should be equipped with auger extensions to within 12 inches of the end gate. When constructing the first lane, a string line should be employed to guide the paver operator to establish a uniform edge. FY 2023 Project Planning Guide FY 2022 Project Planning Guide Requesting a ProjectWise Folder Federal Aid Buyout Program Urban Road Program Rural Road Program Bridge Program TAP RAP should be stockpiled* and tested according to existing requirements (one test per 1000 tons, minimum of three tests). Does the distributor have a capacity of at least 800gallons (3,000 liters)? The faster a roller passes over a point on the asphalt surface, the less time the weight of the roller has to work on that point; this means that less compactive effort is applied to the mixture. Resources for the development of quality transportation project documents and services. A scalping screen should be placed in the aggregate cold feed charging system and the RAP feed system to remove any oversize material. TRAC engages high school and middle school students in solving real-world problems, such as designing bridges or analyzing the environmental effects of building a highway.