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2Traffic congestion, especially in metropolitan areas, places a significant and serious burden on the public and threatens the economic vitality of the nation. A significant portion of traffic congestion is attributable to roadway construction and maintenance activities (10 to 24 percent as reported in various studies). One way to reduce the congestion effects of roadwork activities is to perform such activities during times of reduced traffic demand. Traffic demand fluctuates dramatically over a 24-hour period; the percentage of daily traffic each hour of the day is much less during the evening and early morning hours than it is during the daytime. Data taken during the summer of 2001 suggest that one-third of the work zones present on national highway system roadways were active primarily at night, compared to 58 percent of the work zones that were active during the day (and nine percent of the projects involved continuous work activities over both daytime and nighttime hours) (Ullman et al. 2004). The Problem Although the benefits to performing work activities at night are obvious and significant, par- ticularly on high-volume roadways in urban areas, a number of issues can make night work challenging. Safety of Personnel According to some sources, night work presents challenges to work-crew safety. For example, night work generally involves degraded vision for the workers because of lower overall lumi- nance levels in the work zone, the effects of shadows created by equipment and materials, and glare from vehicle headlights and equipment lights around the work area. In addition, concerns exist over potential degradations in worker attention levels and overall health due to the disrup- tion of the bodyâs natural circadian rhythms. Finally, questions have arisen as to the effect of performing work at night, specifically as it affects worker quality of life as a result of reduced social- and family-interaction opportunities. Safety of the Traveling Public The nighttime work-zone issues related to the driving public that are most commonly cited include the following: ⢠Reduced visibility for drivers due to lower levels of light at night (this is especially an issue for older drivers with vision deterioration). C H A P T E R 1 Introduction and Framework
Introduction and Framework 3 ⢠Decreased driver expectancy for encountering road work activities at night. ⢠Higher percentage of impaired and/or drowsy drivers on the road at night. ⢠Higher traffic speeds approaching and traveling through the work area (potentially leading to more severe crashes). Quality of Work and Production Working at night can have implications on work quality, production rates, and costs for the contractor. These implications may translate into higher project costs for the agency. The effects of lower light levels on worker vision may reduce work quality, and night work can require a cost premium for materials and labor. However, lower traffic volumes make it easier for materials to be delivered to or transported from the jobsite, potentially increasing productivity and reducing overall costs. Construction Nuisances Night work can have impacts on adjacent neighborhoods and businesses that would either not be experienced or not be as disturbing if they occurred during the daytime. These impacts include noise levels that affect sleep patterns of nearby residents, glare from temporary light- ing systems that intrude upon residential dwellings, and accessibility to businesses that operate primarily at night. The hazards, demands, and nuisances have been the subject of a number of previous research studies: ⢠Illumination requirements of nighttime work zones (El-Rayes and Hyari 2005a, El-Rayes and Hyari 2005b, Hyari and El-Rayes 2006a, Hyari and El-Rayes 2006b, and Nassar 2008) ⢠Evaluation of construction nuisances during nighttime work zones (Schexnayder 1999 and Schexnayder and Ernzen 1999). ⢠Evaluation of the impact of nighttime work zones on driver and worker safety (Arditi et al. 2004 and Arditi et al. 2007). ⢠Quantification of the impact of nighttime operations on construction cost and quality (Al-Kaisy and Nassar 2005, Kumar and Ellis 1994, and Lee and Thomas 2007). While previous studies made significant contributions to the advancement of the practice of nighttime construction, this Guidebook seeks to provide a comprehensive assembly of informa- tion concerning nighttime construction work in transportation corridors. According to previous research, 27 state transportation agencies (STAs) reported that they have experienced serious nighttime construction issues (Schexnayder and Ernzen 1999). How- ever, most agencies reported that with appropriate project specifications, a viable nighttime con- struction environment can be created. Controlling specifications need to clearly indicate to the contractor the critical issues associ- ated with a project and how to address them. A good construction specification is an effective tool in mitigating the effects of nighttime construction issues. The mechanisms to achieve that goal will vary from one contract to another because of area-specific conditions, the type of con- struction, the traffic flow that must be handled, the inherent nature of project neighbors, and the desires of the community. Supplemental standard provisions can dictate specific measures on a contract-by-contract basis to address special local issues. The existence and importance of lighting and nuisance con- trol specifications need to be emphasized at pre-bid and pre-construction conferences.
4 A Guidebook for Nighttime Construction: Impacts on Safety, Quality, and Productivity The Decision The decision to conduct construction activities at night can be made at various levels of the STA and at various points in the project development process or even by a construction com- pany, depending on the individual project. However, this decision needs to be made as early in the project development process as possible and communicated to all project participants throughout the remainder of project development and construction. This is to ensure that the decision is reflected in the project planning, design, and cost estimation. The Project Development Process Transportation projects typically go through five phases of project development (Anderson et al. 2007): 1. Planning. 2. Scoping. 3. Design. 4. Advertise and Bid. 5. Construction. In different transportation agencies, the development phases may have different names; how- ever, these are the typical activities. While Table 1.1 describes the design-bid-build method, the typical activities may vary depending on the project delivery method. The Research Project To help STAs and responsible personnel understand nighttime construction issues, the National Cooperative Highway Research Program (NCHRP) initiated the project that produced this Guidebook. The objective of this guide is to provide comprehensive and concise material to support nighttime highway construction and maintenance operations. Development Phase Typical Activities Planning Determine purpose and need, determine whether it is an improvement or requirement study, consider environmental factors, facilitate public involvement/participation, and consider interagency conditions. Scoping Conduct environmental analysis, conduct schematic development, hold public hearings, determine right-of-way impact, determine project economic feasibility, obtain funding authorization, develop right-of-way, obtain environmental clearance, determine design criteria and parameters, survey utility locations and drainage, make preliminary plans such as alternative utility locations and drainage, make preliminary plans such as alternative selections, assign geometry, and create bridge layouts. Design Acquire right-of-way; develop plans, specifications, and estimates; and finalize pavement and bridge design, traffic control plans, utility drawings, hydraulics studies/draining design, and cost estimates. Advertise and Bid Prepare contract documents, advertise for bid, hold a pre-bid conference, and receive and analyze bids. Construction Determine the lowest responsive bidder; initiate contract; mobilize; conduct inspecting and materials testing; administer contract; control traffic; and construct bridge, pavement, and drainage. Table 1.1. Project development process (Anderson et al. 2007).
Introduction and Framework 5 The material presented in this guide was assembled through a review of literature, surveys, interviews with agencies and contractors, and limited field measurements. Additional informa- tion on the project can be found in the contractorâs final report. The information for this project was collected from many different sources, but the primary sources were STA personnel. A national survey was conducted to collect preliminary informa- tion from each of the state highway agencies regarding each of the nighttime construction areas of interest. Later, more in-depth interviews were conducted to collect additional information and gather field observations. Information was also assembled from published sources. The culmination of information from all sources is presented in this Guidebook. Guidebook Framework This Guidebook provides a practice-oriented presentation of nighttime construction issues. The objective is to provide practitioners with a comprehensive reference on nighttime construction practices. The information in this guide is provided in chapters specific to each of the considerations of nighttime construction. Some of the information and chapters are more specific for night- time activities, while others are more general, primarily because practices may not be different between daytime and nighttime construction. Chapter 1: Introduction and Framework Chapter 1 provides readers with an understanding of the challenges faced in nighttime construction. This chapter also describes the development process for the Guidebook and its layout. Chapter 2: Risk Risks inherent to construction work zones are numerous. The obvious risks are related to safety and include vehicle intrusions in work zones, workers being struck by intruding vehicles, workers struck by construction equipment, and construction equipment intrusion in operational lanes. In addition, other risks in nighttime construction relate to quality, cost, communication, and nuisances. This chapter introduces these risks and includes a discussion on risk management. The remainder of the Guidebook chapters can then be used to address these risks. Chapter 3: Illumination Illumination is not often considered for daytime construction, while it is imperative to suc- cessful completion of a nighttime project. Therefore, illumination is a unique and critical factor in nighttime activities. This chapter presents lighting requirements for highway construction as well as potential lighting guidelines for different nighttime construction activities. Chapter 4: Nuisances Several types of control mechanisms exist for noise nuisances during highway construction. These mechanisms include source, path, and receptor controls. This chapter explores each type of control mechanism and discusses methods found for control of nighttime construction nui- sances. The chapter also touches briefly on vibration and dust nuisances.
6 A Guidebook for Nighttime Construction: Impacts on Safety, Quality, and Productivity Chapter 5: Productivity The productivity levels of nighttime construction have not been researched in depth. This chapter presents ways to improve productivity, as well as potential pitfalls that may be encountered. Chapter 6: Quality The objective of a transportation agency is to provide a quality project. Quality is often one of the keys in contractor payment. Project quality is linked to the inspectability of the product being delivered. This chapter provides information for the visual requirements necessary to inspect different types of work properly, along with information from various agencies on quality efforts in nighttime construction. Chapter 7: Cost The chapter includes discussions about factors that have an impact on cost and guidance on what to consider when planning and budgeting nighttime construction activities. Chapter 8: Safety The safety of nighttime work has an impact on both the traveling public and the construction workers. This chapter examines the safety issues for both. Chapter 9: Communications Many complaints about nighttime construction nuisances can be mitigated through a good communications program. This chapter explores communicationâboth with the public and within the transportation agencyâand presents practices from agencies across the country. Chapter 10: Interactions Chapter 10 of the Guidebook discusses the interactions that are inherent between the topics previously discussed. The factors considered in nighttime construction decisions and planning interact with each other, given that the risks associated with nighttime construction activities are not mitigated exclusively or monitored by only one method. For example, safety can be improved with illumination, but providing illumination can add cost to the project. Chapter 11: Summary for Implementation and Keys to Success The conclusions of the Guidebook offer a final overview perspective of the information pro- vided on nighttime construction. References Source information for the citations in this Guidebook is provided in the references. Acronyms and Abbreviations A look-up table for acronyms and abbreviations used in this Guidebook is provided.
Introduction and Framework 7 Appendix: Sample Safety Quiz This appendix contains a sample toolbox talk, written quiz, and answer sheet on safety activity responsibilities. Guidebook Content Each chapter of the Guidebook generally has three sections: an introduction, body, and con- clusion. Within the chapters, certain types of information are highlighted to call attention to important details. These include key take-aways, tips, and additional resources (Table 1.2). How to Use the Guidebook This Guidebook provides information on primary of areas of interest to consider and deci- sions to be made in planning and conducting nighttime construction and maintenance activities. The Guidebook is intended to act as an overall reference for this topic and explores each of the topical areas separately, and, in addition, looks at the interaction among the topic areas. Considerations about nighttime work need to begin early in the planning or design devel- opment process. Therefore, the audience for this Guidebook spans all members of the project development and construction process within the STA. All users could benefit from reading the Introduction and Framework, Risk, and Summary for Implementation and Keys to Suc- cess chapters. Additional chapters of importance depend on the userâs informational needs as outlined in Table 1.3. Summary Nighttime work on the nationâs highways is becoming more prevalent for a number of rea- sons. At the same time, nighttime work presents a number of challenges. The purpose of this Guidebook is to help individuals and teams who are planning or working on nighttime projects understand and address the challenges of working at night. With proper planning, STA teams can effectively address nighttime construction challenges during the proj- ect development process to ensure a successful project. Symbol Section Name Content Key Take-Away ⢠An indicator of key, not-to-forget informationâfor quick reference. Tip ⢠Possible tips for use of information. Resources ⢠Sources of useful information: o Internet. o Literature. o Agency or group. o Reports. Table 1.2. Guidebook content.
8 A Guidebook for Nighttime Construction: Impacts on Safety, Quality, and Productivity Several of the topics covered in this Guidebook are specific to nighttime construction, such as illumination,whereas others include a discussion that is not all that different from the efforts needed on all projects regardless of the time of day, such as communications. While these discussions are more generic, project personnel are reminded that these roadway construction challenges are no less important and may have a greater impact during nighttime construction. User Chapter Justification Planner 3. Illumination Planning for illumination needs to begin during the earliest stages of project planning and development. 8. Safety Both worker and public safety are paramount to project success. Cost Estimator 3. Illumination Costs to light work areas need to be included in estimates. 4. Nuisances Nuisance mitigation needs to be included in estimates. 5. Productivity Working at night can increase or decrease productivity and have an impact on project estimates. 6. Quality Working at night can affect quality and may have an impact on pay items as well as incentive and disincentive amounts. 7. Cost Lighting costs are of particular interest in cost estimates. Designer 3. Illumination Early installation of permanent lighting can reduce the costs of temporary lighting. 4. Nuisances Nuisance mitigation needs considered during design. 6. Quality Establishing standard quality measures is important so that product quality does not differ for nighttime activities. 8. Safety Different design ideas may need to account for worker and public safety. Project Manager or Field Engineer 3. Illumination Permanent and temporary illumination considerations for the job site need to be monitored and corrected immediately beyond the project planning phase. 4. Nuisances A clear understanding of how to mitigate nuisances is required. 7. Cost Work at night may have an impact on construction costs. 8. Safety A safe project site for agency personnel, contractor personnel, and the traveling public is required. 9. Communications Effective communications within the project group and with the public helps ensure project success. Construction Inspector 3. Illumination Good illumination is required. 4. Nuisances Nuisance mitigation measures need to be monitored. 5. Productivity The project site needs to support productivity. 6. Quality The quality specification for the project must be met. 8. Safety Good safety practices are required. 9. Communications Effective communications, both on the jobsite and with the public, can be the key to a successful project. Table 1.3. Guidebook chapters of particular interest by user role.
