2.0 Overview of the Work Zone Impacts Assessment Process

2.1 Overall Structure

Transportation agencies strive to provide for a safe, efficient, and reliable transportation system for the public. To achieve this, they perform the following two basic types of functions:

Operate, manage, and maintain the existing transportation system.
Identify system deficiencies and improvement needs, and develop and implement appropriate solutions that serve the identified needs.

State Departments of Transportation (DOTs) perform these two functions using a set of processes that include policy, planning, project development, construction/implementation, maintenance and operations, and performance assessment, as shown in Figure 2.1. In the figure, policy is shown as a vertical bar because an agency's policies affect all the steps of the program delivery process to some degree. Performance measurement and system management, maintenance, and operations are shown as vertical bars in Figure 2.1 because these are ongoing activities that are done continuously, rather than at one step in the program delivery process. Work zones are a necessary part of system maintenance and system improvement. Each work zone causes some level of safety and mobility impacts that can be managed by decisions made during the program delivery process.

Figure 2.1 Typical Program Delivery Process[1, 2]

2.2 Incorporating Work Zone Impacts Assessment in Program Delivery

Incorporating work zone impacts assessment in program delivery does not entail an entirely new process; rather, it involves the consideration of work zone impacts issues during pre-existing program delivery activities. Thus, the work zone impacts assessment process described in this Guide is structured to mirror the typical State DOT program delivery process.

Work zone impacts assessment may be incorporated into program delivery by:

Implementing an overall work zone safety and mobility policy at the policy-level.
Conducting a first-cut work zone impacts assessment at the systems planning-level.
Conducting a preliminary project-level work zone impacts assessment during preliminary engineering.
Conducting detailed project-level work zone impacts assessment during design.
Managing work zone impacts during construction.
Conducting work zone performance assessment on a regular basis.
Incorporating work zone impacts assessment procedures in ongoing systems management, maintenance, and operations.

The level of detail and type of work zone impacts assessment varies depending upon the program delivery stage. For example, during systems planning work zone impacts assessment may involve qualitatively identifying the potential work zone impacts of a project, whereas, during design it may involve a more detailed analysis of the work zone impacts. The flowchart shown in Figure 2.2 provides an overview of the overall work zone impacts assessment process described in the remainder of this Guide.

Figure 2.2 Overall Work Zone Impacts Assessment Flow Diagram

Tables 2.1 – 2.6 provide an overview of what happens during the program delivery stages, and how work zone impacts assessment may be incorporated. Many of the key work zone impacts assessment activities are already being performed by agencies. This discussion re-emphasizes them, and incorporates the additional aspects of work zone impacts assessment and management that are advocated by the updated work zone Rule (the Rule). Subsequent chapters provide more detail on work zone impacts assessment during the individual program delivery stages.

Table 2.1 Policy-Level
What happens at the policy-level?	How can work zone impacts assessment be incorporated?
At the policy-level, overall policies and program priorities are established, and applied to the different program delivery stages. As shown in Figures 2.1 and 2.2, policy development and implementation is an over-arching aspect of program delivery that takes place on an ongoing basis. This includes: Setting a vision and developing goals and objectives. Setting policy provisions in the form of requirements, performance standards and/or guidance. Developing and implementing processes, procedures, and practices that help sustain the policy. Applying the policy and its components to the respective program delivery stages. Refining and updating the policy (and its components) periodically.	Work zone impacts assessment starts at the policy-level by setting the tone for an overall work zone policy that supports the systematic consideration and management of work zone safety and mobility impacts. This overall work zone policy may then translate to specific policy components (i.e., vision, goals, objectives, and policy provisions) that help assess and manage work zone impacts through the respective program delivery stages. Many agencies have existing work zone policies. These policies may be updated and/or further developed as needed. In the absence of a pre-existing overall policy, a new one may have to be developed and implemented. Work zone impacts assessment may be addressed at the policy-level by: Adopting an overall work zone policy that supports the systematic consideration and management of work zone safety and mobility impacts. Setting work zone related vision, goals, and objectives; and work zone related policy provisions in the form of requirements, performance standards and/or guidance. Developing processes, procedures, and practices that help sustain the overall work zone policy, and applying them for decision-making during the respective program delivery stages. Updating the work zone policy and its components periodically.

Table 2.2 Systems Planning
What happens during systems planning?	How can work zone impacts assessment be incorporated?
Systems planning constitutes two major groups of activities, namely, "Identifying Transportation Improvement Needs," and "Developing Long-range and Short-term Transportation Plans and Programs." In identifying transportation improvement needs, alternative solutions are developed and evaluated to meet transportation system needs and deficiencies. This is done in many ways, including ongoing review of needs and deficiencies, regional/sub-area/corridor studies, major investment studies (MISs), benefit-cost analyses, environmental/NEPA analyses, and air-quality conformity analyses. Transportation plans and programs are developed by prioritizing the projects identified in the previous step, identifying funding sources, scheduling and coordinating projects, and programming projects to develop Statewide Transportation Improvement Programs (STIPs) and regional Transportation Improvement Programs (TIPs).	The purpose of work zone impacts assessment during systems planning is to understand the work zone impacts of projects at the conceptual planning-level, and identify and cost potential management strategies. This will help allocate resources more effectively to projects early in the project delivery cycle and potentially avoid delays, cost over-runs and change orders in later stages. Work zone impacts assessment may be incorporated in systems planning as follows: Considering work zone impacts issues as a decision-making factor in the assessments/analyses that are performed during alternatives evaluation (e.g., during MISs, NEPA, etc.). Allocating sufficient funds for work zone impacts mitigation and management (based on the considerations and assessments from the previous step). Addressing combined work zone impacts of multiple projects at the regional and corridor levels, coordinating their schedules to minimize impacts.

The transition from systems planning to project development may not always be distinct. Some activities may extend across both systems planning and project development. For example, environmental/NEPA analyses, and the consideration of regional and corridor impacts may extend well into the preliminary engineering phase of projects. Practitioners are encouraged to consider work zone impacts issues during these activities irrespective of the stage in which they take place.

Table 2.3 Project Development (Preliminary Engineering and Design)
What happens during project development?	How can work zone impacts assessment be incorporated?
Project development is where individual projects are developed and designed, and plans are developed for building the project in the field. The majority of work zone impacts assessment currently takes place during project development. The former Rule required only traffic control plans (TCPs) for projects; therefore a majority of work zone impacts mitigation is centered around developing TCPs for projects. Project development consists of two stages – Preliminary Engineering and Design. Preliminary engineering is where early project-level planning and engineering is performed to identify potential construction approaches and develop a preliminary design concept. Currently, very little is done by way of accounting for work zone impacts during preliminary engineering. Design is where detailed analyses and design are performed to develop the final design, construction staging approach, and TCP. Currently, most of the work zone impacts assessment takes place during design.	Current project-level work zone impacts assessment practices may be further enhanced by systematically assessing work zone impacts through the project development stages and by looking at work zone impacts mitigation from a transportation management perspective rather than just a traffic control perspective. The updated Rule requires the development of a transportation management plan (TMP) for each project. During preliminary engineering, this may be accomplished by accounting for the work zone impacts of the potential construction approaches and overall design concept for the project. The assessment during preliminary engineering is generally expected to be qualitative. Design-level work zone impacts assessment may include consideration of corridor and network level impacts, coordination with other projects, addressing work zone impacts issues in conjunction with the project design and construction approaches, work zone transportation management, and development of TMPs. Qualitative and/or quantitative approaches may be used based upon the project characteristics and its expected work zone impacts.

Note: In September 2004, the Federal Highway Administration (FHWA) updated the work zone regulation at 23 CFR 630 Subpart J and renamed it the Work Zone Safety and Mobility Rule (the Rule). Refer to Section 1.6 of this Guide for information on the Rule.

Table 2.4 Construction/Implementation
What happens during construction?	How can work zone impacts assessment be incorporated?
Construction/implementation is where projects are built in the field. Generally, the focus is on implementing the TCP prior to construction, maintaining traffic through the work zone, facilitating safety for motorists and workers, and monitoring and managing the work zone and the construction.	During construction/implementation, the objective is to monitor and manage the work zone impacts of projects on an ongoing basis. This may be done by implementing the TMP, monitoring work zone impacts, and revising the TMP if necessary to improve the performance of the work zone.

Table 2.5 Performance Assessment
What happens during performance assessment?	How can work zone impacts assessment be incorporated?
Performance assessment is where the performance of the processes, practices, and procedures are assessed for their effectiveness, successes, and failures at the project and program levels.	Assessing the performance of individual work zones, analyzing area-wide impacts of multiple projects (before, during, and after construction), synthesizing information to identify trends, and conducting process reviews all provide information that can be used to improve the agency's work zone processes, practices, and procedures.

Table 2.6 Maintenance and Operations
What happens during maintenance and operations?	How can work zone impacts assessment be incorporated?
Maintenance and operations encompass the ongoing activities that are typically performed by an in-house maintenance crew. They encompass both planned and emergency maintenance. Examples of typical activities include installation and maintenance of traffic signs and other roadside devices, debris removal, painting/striping, minor guardrail work, mowing operations, and minor utility work. Such activities generally require short-term and/or mobile work zones. Currently, most agencies employ typical temporary traffic control (TTC) approaches for different types of operations/maintenance work zones. These typically are based on engineering judgment and analyses, and generally focus on the safety aspects of these work zones.	Current work zone impacts assessment and management practices for maintenance and operations may be enhanced by: Applying work zone impacts assessment and management to different categories of operations/maintenance projects, monitoring their performance, and making revisions to processes and practices on an ongoing basis. Mainstreaming processes to assess impacts of operations and maintenance work zones. Revisiting typical TTC approaches and updating them to meet current work zone safety and mobility needs. Considering the mobility aspects of maintenance work in addition to safety.

2.3 Work Zone Impacts Considerations

The essence of assessing and managing the work zone impacts of road construction and maintenance projects lies in:

Safety - Maximizing the safety of road users and highway workers.
Mobility - Maximizing mobility and accessibility on roadways.
Constructability - Planning, designing, and building projects as effectively and efficiently as possible.

Safety, mobility, and constructability are the three critical work zone related issues that need to be addressed while planning, designing, and building road projects. Constructability can be defined as the optimum use of construction knowledge and experience in planning, design, procurement, and field operations to achieve overall project objectives. The objective of constructability is to facilitate rational bids and minimize problems during construction. Benefits of constructability include cost reduction, schedule adherence, higher productivity, enhanced quality, and more safety and convenience for the traveling public.[3] Constructability reviews are performed to facilitate the practicality of construction and minimize project delays, changes, and costs, while at the same time maximizing productivity, quality, safety, and convenience.

TIP: Constructability and value engineering may be similar in that they require reviews of project plans and designs; however, their purposes are vastly different. Value engineering provides for the necessary functions while reducing or eliminating project costs. Value engineering is normally performed during the design and/or construction phase, whereas constructability needs to be reviewed on an ongoing basis throughout project development. More information on value engineering is available on the Federal Highway Administration (FHWA) Value Engineering web site at https://www.fhwa.dot.gov/ve/index.htm.

As work zone impacts assessment is performed progressively through the various program delivery stages, the three basic issues of safety, mobility, and constructability are addressed in an iterative manner. Information from one stage feeds into the next, with the level of detail of the assessment progressively increasing from stage to stage. The objective is to achieve constructability without compromising safety and mobility. Safety, mobility, and constructability are affected by the following types of issues, including:

Project characteristics.
Travel and traffic characteristics.
Corridor, network, and community issues.
Design, procurement, and construction options.
Work zone design and safety issues.
TTC strategies.
Transportation operations (TO) strategies.
Public information (PI) strategies.

Table 2.7 provides an overview of different work zone impacts considerations for each of these issues. Additional detail on these considerations is provided throughout this document at appropriate locations.

Table 2.7 Work Zone Impacts Considerations
Project Characteristics
Project type. Project size, extent, duration, and complexity. Roadway classification. Area type (urban, suburban, rural).
Travel and Traffic Characteristics
Traffic demand and volumes. Seasonal and temporal variations in demand (hourly, daily, or weekly). Occurrence of special events. Percentages of different vehicular volumes (autos – Single-Occupancy Vehicle, High-Occupancy Vehicle; trucks; or buses). Type of travel (commuter or tourist), freight corridor, transit corridor. Public and private facility access issues. Potential impacts of weather. Other such similar characteristics.
Corridor, Network, and Community Issues
Impacts of the project at both the corridor and network levels including parallel corridors, alternate routes, the transportation network, other modes of transportation, and impacts of other work zones in the vicinity of the project, either at the corridor level or the network level. Impacts on nearby transportation infrastructure such as key intersections and interchanges, railroad crossings, public transit junctions, and other junctions in the transportation network. Impacts on evacuation routes in the vicinity of critical transportation or other infrastructure. Impacts on affected public properties, including parks, recreational facilities, fire stations, police stations, and hospitals. Impacts of the project on affected private properties, including businesses and residences.
Design, Procurement and Construction Options
Temporal alternatives for work performance such as season, month, day of week (weekend versus weekday), and time of day (night time versus day, off-peak versus peak). Alternative lane closure strategies such as full closure, partial closure, crossovers, multiple lane closure, single lane closure, and impact of alternative traffic management strategies on lane-closure decisions. Alternative design solutions that address the durability and economy of maintenance of the roadway. Alternative design solutions and strategies that impact decision-making on right-of-way (ROW) acquisition. Alternative construction staging plans, and construction techniques and methodologies (e.g., accelerated construction techniques) that may have varying types and severity of work zone impacts. Alternative contracting methodologies such as design-build, A+B bidding, and incentive/disincentive contracting.
Work Zone Design and Safety Issues
Cross-sectional issues such as lane widths, shoulder availability and widths, and number of lanes available for travel. Longitudinal issues such as taper widths, taper lengths, and stopping sight distance. Horizontal and vertical sight distance. Project signing and advance warning. Roadside devices and safety. Work area separation, channelization, and protection (e.g., positive separation, barrels, cones, clear zone considerations, construction zone intrusion detection). Work area and worker delineation (visibility, retroreflectivity, etc.). Work site access and access points. Visibility issues (e.g., night-time work, lighting, fog). Curvature and gradient – vertical and horizontal. Speed – posted speed limits, speed zoning, etc. Work zone enforcement (e.g., use of uniformed police officers and/or patrol cars, active enforcement using radar guns and/or automated enforcement).
TTC Strategies
Traffic safety and capacity requirements. Alternate route scenarios. Potential impacts on other corridors, nearby intersections/interchanges, and the larger transportation network. Lane closure types and strategies (full-closure, lane-width restrictions, cross-overs, positive separation, etc.). Work zone and work area configurations. Traffic safety and control checklists for developing a TMP.
TO Strategies
Deployment of ITS technologies for work zone traffic monitoring and management. Provision of real-time traveler information to the public, including web-based information. Application of transportation systems management (TSM) and corridor management strategies, including mitigation treatments for alternate routes (e.g., traffic signal timing adjustment on affected corridors), and alternate modes (e.g., public transit subsidies, incentives, and special programs). Coordination of transportation management with existing regional transportation management centers (TMCs). Conduct of mobility and safety reviews and audits. Speed enforcement and management in work zones using either police officers or automated techniques. Traffic incident management plans for work zones. Policies on work zone traffic management during emergencies (e.g., hurricane evacuations).
PI Strategies
Provision of project and work zone information prior to the commencement of the work in order to make the public aware of the expected work zone impacts and the State's actions to mitigate the impacts. Recommendations to the public on commuter alternatives, such as information on alternate routes and/or modes. Provision of information on changing conditions on the project during implementation (e.g., changes in lane closure scenarios, construction staging, construction times, or alternate routing). Obtaining public input for the development of appropriate work zone impacts management strategies during the planning and design phases of the project; refinement of work zone management strategies during project implementation; and feedback on performance of the work zone and the project following the completion of the project. Dissemination of information through brochures, pamphlets, and media sources including newspapers, television, radio channels, and web sites. Public meetings and hearings. Coordination and cooperation with affected public and private parties.

Developing and Implementing Transportation Management Plans for Work Zones provides a focused discussion on TTC, TO, and PI strategies along with overview discussions, applicability, advantages, and disadvantages. This Guide is available at http://www.ops.fhwa.dot.gov/wz/resources/final_rule.htm (Accessed 1/18/06).

Appendix A presents an example application of how the overall work zone impacts assessment process described in this Guide can be applied to a project. The appendix discusses the work zone impacts issues faced by the project and describes the strategies used for the project to mitigate work zone impacts.

STIP – Statewide Transportation Improvement Plan; TIP – Transportation Improvement Program
NEPA – National Environmental Policy Act
National Cooperative Highway Research Program (NCHRP) Report 390, Constructability Review Process for Transportation Facilities, Stuart Anderson and Deborah Fisher, National Academy Press, 1997.

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