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1 Construction of new concrete roads and overlays and major rehabilitation of concrete pavements can be effectively and efficiently performed under traffic conditions, as has been demonstrated on several projects across the United States. To accomplish this, transporta- tion agencies have embraced advances in materials, equipment, placement techniques, proj- ect delivery, project management, and public outreach, as well as advances in procurement, payment, and coordination methods. The purpose of this synthesis report is to compile, review, and document current prac- tices and advancements pertaining to construction and rehabilitation of concrete pave- ments under traffic. As part of this synthesis project, a literature review was conducted, and a survey questionnaire was distributed to highway transportation engineers at 52 transpor- tation agencies (all 50 U.S. state highway agencies, the Illinois Tollway, and the District of Columbia Department of Transportation) to document agency practices. A total of 45 sur- vey responses were received, which included responses from agencies indicating that they did not use, or rarely used, concrete pavements. Case examples illustrating a variety of proj- ects with different situations and considerations are also presented. Work zone management and maintenance of traffic considerations are important aspects of construction and rehabilitation of concrete pavements under traffic. While agencies continue to use traditional tools, such as temporary pavements, driver advisory signs, and portable signs in work zone areas, they have also begun to use other techniques, such as pilot cars operated 24 hours per day and 7 days per week and staged (rolling) detours. Many agencies have been conducting rehabilitation work during nighttime hours and during weekend windows to avoid traffic impacts. Agencies have also been modifying their permitting practices to accommodate accelerated construction needs while con- structing under traffic. A variety of cementitious materials have been developed over the past few decades that allow for both rapid placement and early opening to traffic. The durability of these types of materials has improved, although further improvement is needed. In many cases, costs have been reduced relative to conventional materials. An important research need for rehabilitation of concrete pavements under traffic is the development of long-lasting and crack-resistant rapid-setting concrete materials to perform full-depth repairs of con- crete pavement during an overnight closure. Precast concrete pavement technologies are sometimes used for this purpose. Optimization of base and subbase materials to reduce transport time and minimize schedule impacts from the environment provide more effec- tive pavement designs for new construction or reconstruction. The use of these materials promotes construction and rehabilitation under traffic by allowing limited lane closure times and expedited construction schedules. S U M M A R Y Construction and Rehabilitation of Concrete Pavements Under Traffic
2 Construction and Rehabilitation of Concrete Pavements Under Traffic Advancements in paving equipment and placement techniques have had perhaps the most significant impact on construction under traffic. Development of the zero-clearance paver and use of stringless paving and three-dimensional modeling technology have resulted in much greater flexibility in maintaining traffic during placement. Zero-clearance pavers facilitate paving with tight clearances and can allow traffic movement in close proximity to the actual placement. Stringless paving eliminates the need for setting stringlines for machine guidance and elevation control and can therefore permit placement under traffic on even two-lane facilities. Early-age saw-cutting and sensors for early-age maturity are also increasingly being used. As in the case of paving equipment, paving operations can also affect the extent and dura- tion of traffic impacts. Decisions on closures, detours, two-lane versus one-lane paving, and haul roads all play a key role in how quickly a project can be completed and in maintenance of traffic plans. Agencies are exhibiting flexibility in terms of paving operations, such as considering time and access requirements to identify the project paving goals or considering two-lane versus one-lane paving. Proper management of a construction project is necessary to ensure that the project is proceeding as planned, so that it is completed on time and within budget, while meet- ing agency needs for quality, safety, and traffic impacts. Agencies have also started using risk management tools and systems, geographic information system and data management tools, and e-Construction tools for managing projects. The mechanism of project delivery is another factor that has a bearing on construction projects in terms of how they are managed and executed. Agencies are using or considering using mechanisms such as designâbuild and its variations, including designâbuildâmaintain and designâbuildâwarrant, publicâprivate partnerships, and construction manager/general contractor as a way to speed decision-making processes and reduce overall project duration, which in turn can affect the extent to which traffic is affected. Methods of procurement such as cost-plus-time (also referred to as A+B) bidding, alternative technical concepts, and faster decision making through partnering are increasingly being used to shorten project durations and reduce traffic impacts. Various forms of incentives and disincentives are effective tools that can be used by an agency to accelerate construction and reduce delays and corresponding traffic impacts. The majority of agencies use liquidated damages for late completion of new construction or for late opening to traffic after nighttime rehabilitation, or incentive/disincentive provisions for early completion of the project. Practices such as lane rentals and flexible notice-to-proceed dates are also becoming increasingly common. Project-related communications, public outreach, and providing motorists with timely information are even more crucial when constructing concrete pavements under traffic as compared to conventional construction practices. While agencies continue their traditional practices of preconstruction conferences, prepaving team meetings, changeable message signs, and press releases or media alerts, they are increasingly using social media, project websites, email lists, and even third-party applications to reach out directly to the affected public and motorists in a timely and effective manner. In the survey responses, agencies expressed some concerns and reservations about modi- fying practices for construction and rehabilitation of concrete pavements under traffic. The primary concerns were potentially higher bid prices, local construction contractor resis- tance, absence of established performance criteria/standards, perceived negative impact on competition (i.e., reduced number of bidders, particularly among small contractors), and possible increases in disputes with contractors and litigation.
Summary 3 The literature review, agency survey, and telephone discussions with agency engineers suggest there are many technologies, practices, materials, and equipment strategies that can be considered for the construction and rehabilitation of concrete pavement under traffic. However, most of these were not specific or unique to construction and rehabili- tation of concrete pavement under traffic. For example, pilot cars with one-lane traffic, changeable message signs, liquidated damages, and other practices have been used for asphalt pavement construction as well. Stringless paving, roller-compacted concrete, and many other technologies, practices, materials, and equipment are increasingly being used as standards of practice regardless of traffic. Often, the construction and rehabilitation of concrete pavements are not isolated activities but part of a larger project that could include bridges, culverts, guardrails, drainage improvements, ramps, intersections, inter- changes, viaducts, and so forth. As such, the construction of the concrete pavement itself is only a part of all the various factors that are considered by agencies on any given project. However, as the case examples show, these technologies, practices, materials, and equip- ment are helpful when used in situations where traffic is a major consideration.