6.0 Work Zone Impacts Assessment During Design

6.1 What Happens During Design?

Design represents the stage in program delivery where the final design is conducted for the project and appropriate plan documents, specifications, and cost estimates are developed. These documents lay out exactly how the project will be built, what the issues are, and how the work zone will be implemented and managed. Design is an iterative process that consists of different stages, sometimes referred to by different percentages such as the 30% stage (preliminary engineering), the 60% and 90% stages, and then the final design for the project. Through the course of these design stages, final decisions are made on the best options for all the aspects of the project. Based on these decisions the final plans, specifications, and estimates (PS&Es) and the bid package are developed, followed by bidding and contract award.

The following is a summary of the activities that are performed during design:

• Conducting further analysis and design.
• Choosing the best build option.
• Choosing project design and contracting strategy.
• Addressing right-of-way (ROW) and other issues (e.g., utility relocation, coordination).
• Choosing specific design elements (e.g., structural, pavement, geometry).
• Developing construction staging plan(s).
• Developing plans for work zone traffic control and management.
• Developing final cost estimates.
• Developing PS&Es.
• Bidding and contract award.

Preliminary engineering and the subsequent design stages are generally performed by similar staff, i.e., project planners and designers belonging to the design/engineering departments of transportation agencies, either at the central office or the region/district level. Their primary responsibility is to plan, develop, and design specific projects. Often preliminary engineering and design take place in tandem without a clear-cut distinction between the stages. However, this document discusses work zone impacts assessment for preliminary engineering and design in separate chapters. This was done to emphasize the importance and potential benefits of specifically advancing work zone considerations to the preliminary engineering stage, and to highlight some of the early work zone impacts assessment activities that may be performed during preliminary engineering. Such advancement of work zone considerations could make project development and work zone impacts assessments more systematic. The discussion of work zone impacts assessment separately for preliminary engineering and design is not intended to imply that decision-making by transportation agencies is highly compartmentalized.

6.2 Objectives of Work Zone Impacts Assessment During Design

Design is the stage where the final work zone impacts assessment is conducted so as to choose the best construction/staging option(s), the most suitable design and contracting approach, and the most appropriate work zone transportation management strategies. The impacts assessment during design is an iterative process progressing through the various stages of design, and addressing the basic issues of safety, mobility, and constructability. Basic assumptions are re-examined and appropriate changes are made. Consensus of all involved parties is sought, and performance objectives for the work zone are developed.

Most agencies have extensive design manuals, customized versions of the Manual on Uniform Traffic Control Devices (MUTCD)[1], and standards that help assess work zone impacts and develop appropriate work zone strategies. Typically these work zone strategies are limited to traffic safety and control strategies within the work zone or just adjacent to it. Transportation management strategies are not always included. However, there is an increasing recognition that traffic management efforts beyond temporary traffic control (TTC) plans are needed to deal with the increasing traffic volumes using the same roads on which agencies need to perform maintenance and rehabilitation.[2] Therefore, the focus of this guidance is to enhance design-level work zone impacts assessment by considering and addressing work zone impacts from a broader transportation management perspective, rather than solely a traffic safety and control perspective. This broader approach leads to the development of a transportation management plan (TMP) for the project that includes a TTC plan, as well as other appropriate strategies.

The objectives of work zone impacts assessment during design are to:

• Perform a detailed project-level work zone impacts assessment progressively and comprehensively through the various design iterations.
• Reassess and confirm whether the project is a significant project[3].
• Develop recommendations for final construction approach and construction staging.
• Identify final design and contracting strategies – consider innovative design and contracting approaches.
• Develop final recommendations and plans for work zone management strategies.
• Estimate the final costs for the chosen work zone management strategies.
• Identify performance requirements[4] for the work zone.
• Develop the TMP, appropriate PS&Es, and other documents that are required to implement the TMP.
• Develop contracting documents.

The TMP may be developed by the agency itself – either in-house or by using a consultant. Alternatively, the agency may choose to allow the contractor to develop a TMP prior to start of work, and/or use performance-based specifications. If the agency chooses to use a contractor developed TMP (instead of an agency developed TMP), appropriate specifications for the TMP are developed, rather than the TMP itself. In either case, TMP development will be governed by agency-developed recommendations and/or performance specifications. All TMPs that are developed by a non-agency entity (e.g., contractor, consultant) must to be approved by the agency. The agency may also have the TMP reviewed, stamped, and approved by a licensed Professional Engineer.

6.3 Who Are the Participants?

The staff that may perform the work zone impacts assessment during design, the inputs and input providers, and the outputs and users of the outputs are shown in Table 6.1.

Table 6.1 Design-Level Work Zone Impacts Assessment Participants

The primary participants are the project design and construction team: Project planners. Designers. Highway Engineers. Traffic Engineers, ITS and operations engineers. Safety Engineers. Construction Engineers.
Inputs	Input Providers
Applicable policies. Outputs from preliminary engineering (the preliminary work zone definition). Any other project specific information that is identified during the design processes (project constraints, identified structural needs, ROW issues, environmental issues, utility and sub-surface information, soil and hydraulic information, construction methods and needs, traffic control and management information, etc.)	Designers, pavement managers, bridge managers, traffic engineers/managers, safety engineers, planners, maintenance managers. Technical specialists such as pavement experts, soil experts, hydraulics engineers, environmental experts, construction engineers, utility coordination personnel (water, sewage, power, gas, telecom infrastructure), traffic management specialists (traffic operations/ITS), marketing/public relations staff, law enforcement personnel. Contractors and contractor associations such as the American Road and Transportation Builders Association (ARTBA), Associated General Contractors of America (AGC), and American Traffic Safety Services Association (ATSSA). Other stakeholder groups, such as local community representatives, business representatives, other public safety agencies, trucking associations, American Automobile Association (AAA).
Outputs	Users of the Outputs
The outputs may be the actual plan documents, and/or recommendations or specifications for developing the plan documents. These include: Analysis reports and other associated documentation (traffic studies, impact studies, benefit/cost analysis, modeling/simulation results, etc.). Any performance requirements or guidelines for the work zone. TMP with detailed components to include the TTC plan, and TO and PI components as applicable. PS&E package. Contracting method, and letting and award information.	The project design and construction team, including designers, traffic engineers, safety engineers, construction management and contracting personnel, and construction and safety inspectors. Other related staff with specific responsibilities for project implementation, such as traffic operations and ITS staff, marketing/public relations staff, law enforcement coordination staff, and law enforcement officers. Executive level managers. Other stakeholders – regional transportation agencies, public safety and emergency services, community associations, etc. Contractor and contractor staff.

6.4 Assessing Work Zone Impacts During Design

Figure 6.1 illustrates the steps involved in work zone impacts assessment during design. Some notes pertaining to the figure are presented in Table 6.2.

Figure 6.1 Design – Work Zone Impacts Assessment Process

Table 6.2 Process Notes

Much of work zone impacts assessment, to the degree it is done, currently takes place during design and is focused on developing TCPs for projects. This guidance is intended to enhance and supplement existing practices towards adopting a broader work zone transportation management approach.

Work zone impacts assessment during design is an iterative process progressing through the different design stages, leading to the final design, TMP, performance requirements/criteria, and PS&Es for the project. Each design stage consists of specific activities, milestones, and concurrence points. Work zone impacts assessment is not intended to be a separate activity, rather it should be included in the ongoing design activities, with work zone impacts issues being accounted for at each concurrence/decision point. The process shown in Figure 6.1 may not always be a one-shot process; sometimes it may take several iterations of the process to develop the final design, TMP, and PS&Es.

Input from and interaction with appropriate sources (as shown in Figure 6.1) may be required during the assessment: Applicable Policies, shown as a green diamond in the diagram, represents the agency's policies and related policy provisions (i.e., policy requirements, standards, and/or guidance) and appropriate processes, procedures, and practices that apply to the particular activity. They help with decision-making on specific issues during the process, such as the level of impacts assessment and the type of management strategies needed for different projects. For example, for a work zone that is expected to cause a delay of 20 minutes or more, an agency's policy may require the TMP to incorporate management strategies that can help minimize and manage that delay, and a quantitative analysis of the expected delay and the potential delay reduction that can be attained by implementing the management strategies. Section 3.4 of this document provides a brief discussion on potential policy provisions for application during project delivery. Technical Specialists, shown as a green ellipse in the diagram, represents input from specialists in specific disciplines including highway engineers, construction engineers, traffic engineers, structural engineers, pavement specialists, environmental specialists, ROW specialists, and hydraulics engineers. Participation of such staff throughout the work zone impacts assessment may lead to decisions that carry over to subsequent project phases without significant alteration. Public/Community, shown as a green square in the diagram, represents input from the general public including motorists, other highway users, businesses, residents, neighborhood groups, etc. This input may be provided through public involvement processes, customer feedback efforts, surveys, focus groups, etc. Public involvement during design may not be as extensive as the public input and feedback processes that occur during systems planning and preliminary engineering.

The interface between design, systems planning, and preliminary engineering may be fluid. Decision-making and activities from one phase may overlap with or extend into the other. For some projects, systems planning, preliminary engineering, and/or design activities may be conducted as part of the same study (e.g., large regionally significant projects that require multi-year studies).

Agencies may combine work zone impacts assessment with environmental/NEPA assessments. Generally, agencies prepare three types of environmental reviews under NEPA: Categorical Exclusions (CE) for small, routine projects with insignificant environmental impacts; Environmental Assessments (EA) for projects with no significant environmental impacts; and Environmental Impact Statements (EIS) for projects with significant environmental impacts. The opportunity exists to combine work zone impacts assessment with the environmental/NEPA assessments. Sometimes the NEPA process can be a primary source of work zone related constraints or inputs for the project. Example of issues that may be addressed include how work zone impacts tie in to the project location and design process, how are work zone impacts weighed against other socio-economic/environmental impacts and other project considerations, etc. More information on NEPA is available at http://www.environment.fhwa.dot.gov/projdev/index.asp (Accessed 12/22/05)

The following sections provide a discussion of the steps shown in Figure 6.1.

Step 1 of 5: Compile Preliminary Engineering Material

This step involves the compilation of the preliminary engineering material (i.e., the preliminary work zone strategy), which should include:

• The project definition.
• Candidate construction/staging approach(es).
• Preliminary assessment of work zone impacts.
• Significant project designation.
• Preliminary work zone transportation management strategies.
• Preliminary cost estimates for the management strategies and the candidate construction/staging approach(es).
• Available information on implementation resources, challenges, and opportunities for the management strategies.
• Available project coordination/conflict information.

If the preliminary engineering work zone strategy has not been developed yet, the agency can follow a process like the one described in Section 5.4 to perform the preliminary engineering work zone impact assessment, and develop a preliminary work zone strategy for the project. For larger projects, preliminary engineering and design may take place as part of one study effort.

Step 2 of 5: Reassess Work Zone Impacts

The purpose of this step is to reassess the work zone impacts of the project so that any issues are identified and addressed before the final design is completed. Reassessment of work zone impacts starts with the preliminary work zone strategy and progresses through the various design stages. As design progresses, more detailed project information becomes available and project-related decisions are finalized (e.g., pavement choice may be finalized, which will influence the total duration of construction). Decisions may be made during later design stages that may change the project parameters, potentially changing the work zone impacts implications of the project. Therefore, the reassessment of work zone impacts should be conducted along with the ongoing design activities, with work zone impacts issues being accounted for at each concurrence/decision point. For example, any design-level constructability reviews[5] and value engineering (VE)[6] studies should be encouraged to look at the potential for work zone impact reductions. Such reassessment can help avoid the propagation of errors to the final design, and potentially avoid costly changes later during construction.

Reassessment of work zone impacts is expected to be a qualitative process to double-check the validity of the assessments and assumptions that were made in earlier stages, as more design decisions are finalized and more information becomes available. If the assessment indicates that the work zone impacts may be different from what was expected, further investigation and analysis may be needed. If not the agency may proceed to final design. Depending on the complexity of the project, the agency may conduct additional quantitative analysis of work zone impacts in Step 3. General guidance is provided in Step 3 on the types of projects for which additional quantitative analysis may be required.

The reassessment of work zone impacts can be done in a manner similar to that described in Step 2 of 6 of the systems planning process (Section 4.5), and Step 4 of 7 of the preliminary engineering process (Section 5.4). The key difference in design is that the assessment is more detailed and specific, and the issues that are identified will lead to the final TMP strategies and design recommendations for the project.

The following are some issues to consider in reassessing work zone impacts during design:

• Project Definition. As design progresses, final decisions are made on various aspects related to the project definition. These include decisions on the exact nature of work to be performed, location, extent, and duration; roadway alignment and ROW; cross-sectional, elevation and super-structure details; pavement and structural needs; soil, hydraulics, and environmental needs; utility related infrastructure and coordination issues; and design parameters. When such decisions are finalized, an assessment should be made to determine if those decisions influence the work zone impacts of the project. Project design options should be chosen with consideration for minimizing their life-cycle work zone impacts (e.g., choosing long-life pavements, designing wider shoulders to facilitate easier maintenance, incorporating other features that reduce the work zone impacts of maintenance/rehabilitation). Project Definition is also discussed in Step 2 of 7 of the preliminary engineering process (Section 5.4).

  At the New York State Department of Transportation (NYSDOT), materials and life cycle costing are key design issues. NYSDOT has incorporated design features to accommodate future work zone mobility needs (e.g., wider bridges to facilitate use of the shoulder as a travel lane during construction, avoiding piers in medians).

  Source: NYSDOT comments in response to the FHWA Advance Notice of Proposed Rulemaking (ANPRM) on Work Zone Safety, June 6, 2002, United States Department of Transportation (U.S.DOT) online Docket Management System. URL: http://dmses.dot.gov/docimages/pdf81/175976_web.pdf (Accessed 01/18/06).

  The FHWA Highways for LIFE program focuses on how to build a highway safer, longer lasting, at a lower cost, and faster. More information on this program is available at https://www.fhwa.dot.gov/hfl (Accessed 01/18/06).

• Constructability/Construction Staging Approach(es). During preliminary engineering and early design, it may not be possible to finalize the construction/staging approach for the project. In design, further investigation is performed and decisions are made on the most suitable construction/staging approach for the project, and constructability issues are identified and addressed. The choice of construction/staging approach directly influences the potential work zone impacts of the project. Therefore, as design progresses and decisions are made, any variations from prior decisions/assumptions should be noted and assessed for their work zone impacts implications. In choosing the construction/staging approach and in conducting constructability reviews, work zone impacts issues should be considered and the selection of construction/staging approach(es) should seek to minimize work zone impacts. Construction staging approach is also discussed in Step 3 of 7 of the preliminary engineering process (Section 5.4), and Step 2 of 6 of the systems planning process (Section 4.5).

  Many agencies have successfully used full road closures for accelerating road construction and minimizing overall impacts to road users. The FHWA developed a series of case studies to provide examples of projects using full road closure for work zone operations. The case studies are available at http://www.ops.fhwa.dot.gov/wz/construction/full_rd_closures.htm (Accessed 01/18/06).

  The National Cooperative Highway Research Program (NCHRP) Report 476 contains Guidelines for Design and Operation of Nighttime Traffic Control for Highway Maintenance and Construction. This report is available at http://trb.org/publications/nchrp/nchrp_rpt_476.pdf (Accessed 01/18/06).

  A Traffic Control Handbook for Mobile Operations at Night is available from the FHWA Office of Safety (http://safety.fhwa.dot.gov – Accessed 8/25/06).

• Work Zone Management Strategies. Design-level decisions can influence the choice of work zone management strategies. As specific decisions are made and milestones are attained, the work zone management strategies should also be reassessed to determine if they still apply and whether they adequately serve the purpose of mitigating the work zone impacts of the project. If not, additional management strategies need to be identified. This reassessment is a quick review as to whether the prior assumptions (from preliminary engineering or other design stages) still apply, or whether the previously identified management strategies need to be modified. For example, the preliminary engineering assessments may result in the identification of two alternative "construction and work zone management approaches" – the first being a night work option with a basic TMP (i.e., TTC plan only), and the second being a daytime work option with a complete TMP (i.e., TTC, TO, and PI included). As design progresses, more information may become available on the feasibility of each of the construction approaches, leading to the elimination of the night work option. Therefore, the second option would be chosen and further developed. Step 6 of 7 of the preliminary engineering process in Section 5.4, and Step 4 of 6 of the systems planning process in Section 4.5 discuss the initial identification of work zone management strategies.

  More detailed information on the different work zone management strategies is provided in Developing and Implementing Transportation Management Plans for Work Zones, available at http://www.ops.fhwa.dot.gov/wz/resources/final_rule.htm (Accessed 1/18/06).

• Work Zone Impacts. Work zone impacts should be reassessed when decisions are made on the construction/staging approach(es) and the accompanying work zone management strategies. The reassessment is expected to be an iterative process that progresses along with the ongoing design activities, with checks and balances being made at the respective design milestones and concurrence points. Work zone impacts issues to address include safety; traffic capacity/demand; community impacts; combined impacts with nearby, concurrent projects; significant project designation; modifications to management strategies; and work zone performance requirements (either policy-level or project-specific). If the reassessment indicates that the chosen work zone management strategies will be effective and help attain the performance requirements/goals for the work zone, the agency would proceed to Step 4 (final design). If not, the management strategies may need to be modified, or additional management strategies may need to be identified as appropriate. For smaller (less complex) projects, the reassessment can be based on simplified tools and rules and/or engineering judgment. For larger (more complex) projects a more detailed (quantitative) analysis may be needed, which is discussed in Step 3. In general, a quick reassessment can indicate whether or not a project would need additional quantitative analysis. General guidance is provided in Step 3 on the types of projects for which additional quantitative analysis may be needed. Table 2.7 – Work Zone Impacts Considerations in Section 2.0 provides a detailed list of the different work zone impacts issues and considerations that may be addressed.

Step 3 of 5: Analyze Work Zone Impacts (As Needed)

This step may be considered as an extension of the work zone impacts reassessment discussed in Step 2. The purpose of this step is to conduct a more detailed (quantitative) investigation and analysis of the work zone impacts. Similar to Step 2, this quantitative analysis should also be performed iteratively, progressing along with the design activities, with the design milestones and concurrence points being used as junctures for work zone related checks.

In the process diagram (Figure 6.1), this step is shown as a box with dashed lines, indicating that this step would be performed on an as-needed basis. It is up to individual agencies to determine whether or not quantitative analysis is needed, based on the type, complexity, and expected work zone impacts of the project. If it is determined that further quantitative analysis is not needed, the agency would skip this step and proceed directly to Step 4.

TIP: Though this step may not be performed for all projects, detailed quantitative analysis during design may be the best way to get a clear understanding of the expected work zone impacts of a project. Most project decisions are finalized during design and this is when the project design/construction team may have the best understanding of how exactly the project will be built. A quantitative analysis conducted during design will probably yield the best estimation of the magnitude, location, duration, and costs of the work zone impacts, and help identify the management strategies that best mitigate these impacts. Further, detailed analysis may potentially avoid omission or oversight of work zone safety and mobility issues prior to final design. It may also help identify and address issues that may lead to a work stoppage during the construction stage (e.g., queue lengths or delays in excess of agency policy).

Quantitative analysis may be used to:

• Confirm and re-examine whether the project is a significant project.
• Choose between alternative project design, construction/staging, and traffic control and management approaches.

  The Massachusetts Highway Department (MHD) routinely performs quantitative analysis to compare the construction time for maintaining traffic through the work zone versus closing the highway and diverting traffic. The objective is to maintain pre-existing levels of vehicular and pedestrian mobility and minimize construction cost and schedule.

  Source: FHWA Work Zone Best Practices Guidebook, April 2000, http://ops.fhwa.dot.gov/wz/practices/best/Default.htm (Accessed 01/18/06).

• Estimate the life-cycle costs of the project, taking into account the cost of maintaining and rehabilitating the facility over its life-cycle.

  The Ohio Department of Transportation (ODOT) uses Life Cycle Costing to select the type of pavement to be used. In the past, pavements were selected for reasons such as supply, personal choice, and maintenance. These reasons were not quantified, were generally subjective, and sometimes did not yield a long pavement life. Life-cycle cost analysis provides quantitative information about the pavement type to use, helps justify decisions, and maximizes pavement cost and life.

  Source: FHWA Work Zone Best Practices Guidebook, April 2000, http://ops.fhwa.dot.gov/wz/practices/best/Default.htm (Accessed 01/18/06).

• Choose between alternative work zone transportation management strategies.
• Understand specific aspects of work zone impacts of the project (e.g., choke points, bottlenecks, diversion patterns, queue lengths, queue build-up and dissipation rates).

  DYNASMART-P is a tool developed by FHWA to model the impacts of operational aspects on the transportation network, including work zones and incidents. The user can represent work zones on the network, and run dynamic simulations to estimate impacts such as traffic backup and queuing, queue length, delay, and the effects of using management strategies (e.g., using DMS to divert traffic to alternate routes). More information on DYNASMART-P is available at http://www.dynasmart.com (Accessed 01/18/06).

• Understand the work zone impacts implications of any value engineering proposals that recommend the removal of certain project elements for cost-cutting purposes.
• Understand the combined impacts and coordination issues with other nearby, concurrent projects.
• Identify the work zone performance requirements/goals for the project (e.g., by analyzing the work zone impacts under different scenarios and developing a range of potential impacts, which can then serve as the basis for the performance goals).
• Set the parameters for any innovative/alternative contracting approach (e.g., in the case of A+B bidding, the objective is to minimize construction duration by getting contractors to bid on the actual work items (Part A), and the total number of days to complete the project multiplied by the daily road user cost stipulated in the contract (Part B). The combined values of A and B determine the winning bid. The agency may need to conduct a quantitative analysis of the work zone impacts to estimate the associated daily road user costs that it needs to stipulate in the contract).

  The Indiana Department of Transportation (INDOT) uses the QUEWZ software to predict congestion and associated user costs. The user cost information is used to establish incentives on A+B Contracts and as criteria for the best alternative for maintaining traffic. The version of QUEWZ used by INDOT has the ability to account for the traffic that will divert from the route. It has been calibrated by INDOT and found to be reasonably accurate in user cost and delay estimation, resulting in more efficient construction phasing and maintenance of traffic planning.

  Source: FHWA Work Zone Best Practices Guidebook, April 2000, http://ops.fhwa.dot.gov/wz/practices/best/Default.htm (Accessed 01/18/06).

• Justify additional funds for work zone management strategies, or to justify why a project will not have major work zone impacts. (e.g., by quantifying the work zone impacts, the associated user-costs, and the benefits and costs of the work zone management strategies).
• Determine and design the specific aspects of the management strategies.
  • TTC Plan – quantify expected queue length and incorporate that information in designing the taper for the project; design the lane-widths; set the work zone speed limits; estimate costs of TTC strategies; etc.
  • TO Component – determine the communications and detector requirements for a work zone traffic monitoring and incident management system; estimate traffic diversion patterns and rates to determine potential impacts on the alternate route(es) and appropriately improve operations on the alternate route (e.g., signal timing adjustments); evaluate the positioning of dynamic message signs (DMS) which may affect the diversion patterns; estimate the number of people who would switch to transit so as to structure the transit incentive program; estimate the costs of the TO strategies; etc.
  • PI Component – estimate the volume of traffic that would be affected by the project to determine the PI needs; determine the types of PI strategies to use (e.g., real-time updates through email, telephone based information); coordinate with stakeholders to initiate the PI program; estimate the costs of the PI strategies; etc.

Quantitative impacts analysis may generally be needed for significant projects that are expected to have major impacts at the corridor, network, or regional levels, but this does not mean that it will not be needed for other projects. A decision to analyze or not to analyze should be made on a project-by-project basis. The following provides some general guidance to help agencies determine the types of projects for which detailed quantitative analysis may be appropriate:

• Section 3.4.1 discusses the classification of projects according to their expected work zone impacts. Table 3.2 in that section presents the project classification scheme used in the FHWA Work Zone Self Assessment program,[7] which classifies projects into four types. The project complexity and expected work zone impacts is highest for Type I projects, followed by Types II, III, and IV, respectively. In general, quantitative analysis of work zone impacts may be appropriate for all Type I and Type II projects; may be needed for some Type III projects; and may not be needed for most Type IV projects.
• Section 3.4.1 also presents a classification scheme based on the type of TMP that may be needed for projects. The example classification scheme uses three types of TMPs - Basic TMP, Intermediate TMP, and Major TMP. Using this classification scheme, quantitative analysis may not be needed for most Basic TMP projects; may be needed for some Intermediate TMP projects; and may be needed for most Major TMP projects.

Quantitative analysis can be performed at the work zone, corridor, and/or network levels. Appropriate measures may be considered in the analysis for safety, mobility, societal impacts, road user-costs, life-cycle cost implications, and benefits of the work zone management strategies. Examples of different work zone impacts issues and measures are provided in Step 3 of 6 in Section 4.5 (Systems Planning Process) and under Step 5 of 7 in Section 5.4 (Preliminary Engineering Process). The key difference in design is that the analysis is more detailed and will lead to the development of the final design and TMP for the project. The level of detail and clarity of analysis is expected to be higher. For example, early work zone impacts analysis performed during preliminary engineering (e.g., using a sketch-planning tool) for a particular project may indicate that traffic diversion to the designated alternate route for the project would be significant, leading to a preliminary decision to upgrade and re-time the traffic signals on the alternate route. In design, a more detailed analysis (e.g., using a micro-simulation tool) may be conducted to determine the actual diversion patterns, the volume of traffic expected to divert to the alternate route, and the actual intersections that would be affected. This analysis may then be used to identify the number of traffic signals that need to be upgraded and the exact nature of the upgrades, and to develop the signal timing plans and estimate the costs for the same.

In addition to the measures in Section 4.5 and Section 5.4, agencies may be interested in understanding some more specific operational issues during the design level analysis. Examples include queue build-up and dissipation patterns/durations, queue lengths, traffic diversion patterns/volumes, effects of slight modifications in work duration (i.e., changes in start and stop time), vehicle trajectory analysis (e.g., to understand the impacts of tight curves and lane shifts), benefits of specific management strategies (e.g., travel time savings that may be attained by deploying a work zone traffic monitoring and incident management system, speed and crash reduction that may be attained through a speed advisory and enforcement program, overall mobility savings that can be attained through a work zone traveler information program).

Key technical issues to be addressed in the analysis include:

• Constructability (project cost, schedule, construction effectiveness and efficiency, construction staging, work area access, construction quality, environmental constraints, utilities, noise, weather interference, project coordination and interdependencies, any interference with/to ongoing maintenance activities, etc.).
• Work Zone Impacts (crashes; queues; recurring delay; non-recurring delay; traffic diversion; nearby railroad crossings; transit junctions; interchanges/intersections; impacts to businesses/residents; combined impacts with nearby, concurrent projects; user-costs of the impacts; etc.). Table 2.7 – Work Zone Impacts Considerations in Chapter 2.0 provides a detailed list of the different work zone impacts issues and considerations that may be addressed.
• Work Zone Management Strategies (TTC, TO, PI, innovative design and contracting, advanced construction technologies, coordination with other projects, combining multiple projects, etc.).

More detailed information on the different work zone management strategies is provided in Developing and Implementing Transportation Management Plans for Work Zones, available at www.ops.fhwa.dot.gov/wz/resources/final_rule.htm (Accessed 1/18/06).

The three technical issues presented above are briefly explained in Steps 2, 3, 4, and 5 of the systems planning process in Section 4.5; and Steps 3, 4, 5, and 6 of the preliminary engineering process in Section 5.4. The key difference in design is the level of detail in analyzing and addressing individual issues.

Deterministic/Highway Capacity Manual (HCM) based tools, traffic simulation models, and other tools that can help perform a detailed analysis may be most appropriate for this level of analysis. The objective of quantitative analysis during design is to analyze and address specific issues in detail, and make final decisions and recommendations towards development of the final design and TMP for the project. Detailed analysis tools such as deterministic tools and traffic simulation models may be most suitable. Higher-level travel demand models and sketch planning tools may also be used if the project situation warrants their use (e.g., budgetary constraints, regional impacts, readily available model from the agency's planning division). Sometimes a combination of different levels of tools may be needed to appropriately analyze the impacts. Many agencies also use tools that are developed in-house and are customized according to their respective policies and program priorities.

Deterministic tools are capable of providing accurate results for specific locations or small roadway sections provided there is adequate information on traffic volume, roadway geometrics, traffic control and management features, and any roadside friction that may exist. For example, an HCM-based deterministic tool can replicate the TTC plan for a project (i.e., taper lengths, number of lanes, lane widths, shoulder widths, turning lanes, traffic signal information), and predict the delay and queue length for the corridor on which the work zone is setup. A tool such as QuickZone (which uses both deterministic and sketch-planning methods) can estimate queues and delays on the mainline corridor and diversion to the adjoining network. It also provides a high-level estimate of the benefits of different management strategies (e.g., ITS, demand management, real-time information). However, if agencies are interested in simulating the effect of the work zone on a dynamic basis[8] (e.g., determine the roadways to which traffic may divert, estimate queue development and/or discharge rates, estimate queue durations, identify traffic overflow/spillback, estimate the operating effects and benefits of management strategies) simulation models may be most suitable.

Examples of tools that may be most appropriate for conducting the design-level quantitative work zone impacts analysis are:

• Work Zone Specific Sketch-Planning Tools such as MicroBENCOST, QuickZone, QUEWZ, and CA4PRS.
• Deterministic/Highway Capacity Manual (HCM) Based Tools such as Highway Capacity Software (HCS 2000), Assessment of Roundabout Capacity and Delay (ARCADY), Freeway Delay Calculation Program (FREWAY), and Dynamic Toll Plaza Queuing Analysis Program (Dqueue).
• Traffic Simulation Tools such as:
  • Macroscopic Simulation Models such as Bottleneck Traffic Simulator (BTS), CORFLO, and NETCELL.
  • Mesoscopic Simulation Models such as DYNASMART-P, DYNAMIT-P, etc. Microscopic Simulation Models such as TSIS/CORSIM, PARAMICS, and VISSIM.

The quantitative analysis may be combined with an ongoing project study such as corridor/sub-area study, EIS, etc. Environmental/NEPA assessments must cover the range of impacts of the project, and address issues such as design alternatives that would decrease pollution emissions, construction impacts, esthetic intrusion, relocation assistance, possible land use controls that could be enacted, and other possible efforts. Any work zone impacts analysis that is conducted during design may be combined with other such project assessments, can provide information towards effective completion of other assessments, and can use information and constraints that come out of the other assessments. This applies especially to large projects for which planning, preliminary engineering, and design are performed as part of the same study.

Based on the results of the analysis, the agency may choose to either revise the management strategies and/or the construction/staging approach for the project. This represents the iterative aspect of the work zone impacts assessment process. Decision-making at this juncture is driven by the required level of performance for the work zone (as determined by the agency and/or design team, or as defined by applicable policies and standards).

Step 4 of 5: Develop/Recommend Final Construction Staging and TMP

In this step, information from the previous steps is used to complete the final design, the construction staging, the TMP, and the cost estimates for the project. These are then compiled into the PS&E package. Agencies may arrive at this step directly after the reassessment in Step 2, or after conducting further quantitative analysis in Step 3. In some agencies and/or for some projects, these plans and documents may not be finalized until the construction stage. Also, TMP development responsibility and sequencing may vary according to the chosen design approach and contracting strategy.

• Traditional Design-Bid-Build process. In this case, the final plans, TMP, PS&E and bid package are developed by the agency (or consultant as appropriate).
• Design-Build. This involves a stage-by-stage approach to designing and building the project, where design and construction take place in tandem. When construction is taking place on one phase, the subsequent phase is designed. This generally saves project time and money. This approach is more often adopted for major infrastructure reconstruction or rehabilitation projects and is performed by a team of engineering consultants and contractors.
• Contractor Developed TMP. In this case, the agency includes basic TMP requirements and recommendations in the bid package, rather than the agency developing the TMP itself. Contractors may then include appropriate TMPs in their bids.
• Performance Based TMP. In this case, work zone performance requirements are established by the agency. Contractors may then include TMPs that help meet those performance requirements in their bids.

All TMPs that are developed by a non-agency entity (e.g., contractor, consultant) must be approved by the agency. The agency may also have the TMP reviewed, stamped, and approved by a licensed Professional Engineer.

As stated in the updated Rule[9] (the Rule), the TMP for a significant project must consist of a TTC plan, and also address TO and PI components. TMPs for all other projects must consist of a TTC plan, with the consideration of TO and PI components being encouraged as appropriate.

The following provides some general guidance and resources for TMP development, based on information provided in Implementing the Rule on Work Zone Safety and Mobility[10]:

• A TTC plan describes TTC measures to be used for facilitating road users through a work zone or an incident area. The TTC plan plays a vital role in providing continuity of reasonably safe and efficient road user flow and highway worker safety when a work zone, incident, or other event temporarily disrupts normal road user flow. The TTC plan must be consistent with the provisions under Part 6 of the MUTCD and with the work zone hardware recommendations in Chapter 9 of the American Association of State Highway and Transportation Officials (AASHTO) Roadside Design Guide. In developing and implementing the TTC plan, pre-existing roadside safety hardware must be maintained at an equivalent or better level than existed prior to project implementation. The scope of the TTC plan is determined by the project characteristics, and the traffic safety and control requirements identified by the agency for that project. The TTC plan must either be a reference to specific TTC elements in the MUTCD, approved standard TTC plans, agency TTC manual, or be designed specifically for the project.

  Chapter 9 of the AASHTO Roadside Design Guide is entitled, ''Traffic Barriers, Traffic Control Devices, and Other Safety Features for Work Zones." The entire document is available for purchase from the American Association of State Highway and Transportation Officials (AASHTO), 444 North Capitol Street, NW., Suite 249, Washington, DC 20001 or at the URL: http://bookstore.transportation.org (Accessed 01/18/06). It is available for inspection from FHWA Headquarters and Division Offices.

• The TO component of the TMP includes strategies that will be used to mitigate impacts of the work zone on the operation and management of the transportation system within the work zone impact area. Typical TO strategies may include but are not limited to demand management, corridor/network management, safety management and enforcement, and work zone traffic management. The scope of the TO component should be determined by the project characteristics, and the transportation operations and safety strategies identified by the agency.

  The FHWA conducted a cross-cutting study on several deployments of ITS in work zones. This report, "Intelligent Transportation Systems in Work Zones: A Cross-Cutting Study," showcases four examples and is available at http://www.ops.fhwa.dot.gov/wz/its/index.htm (Accessed 01/18/06).

• The PI component of the TMP includes communications strategies that seek to inform affected road users, the general public, area residences and businesses, and appropriate public entities about the project, the expected work zone impacts, and the changing conditions on the project. This may include traveler information strategies. The scope of the PI component should be determined by the project characteristics and the public information and outreach strategies identified by the agency. Public information should be provided through methods best suited for the project, and may include information such as the project characteristics, expected impacts, lane closure details, and commuter alternatives.

  The Virginia Department of Transportation (VDOT) uses special management and operations plans on selected, high traffic volume projects (usually Interstate projects). These include the use of incentive and disincentive clauses to expedite the work, A + B type bidding taking both project cost and user delay into consideration, using public input in determining the construction strategy and least impact to the business community, and extensive public awareness campaigns.

  Source: VDOT comments in response to the FHWA Advance Notice of Proposed Rulemaking (ANPRM) on Work Zone Safety, June 6, 2002, United States Department of Transportation (U.S.DOT) online Docket Management System. URL: http://dmses.dot.gov/docimages/pdf81/176059_web.pdf (Accessed 01/18/06).

  More specific guidance on designing a public information and outreach campaign for work zones is provided in Work Zone Public Information and Outreach Strategies, available at: http://ops.fhwa.dot.gov/wz/resources/final_rule.htm (Accessed 11/18/05).

• Agencies should develop and implement the TMP in sustained consultation with stakeholders (e.g., other transportation agencies, railroad agencies/operators, transit providers, freight movers, utility suppliers, police, fire, emergency medical services, schools, business communities, and regional transportation management centers).
• The PS&Es must include either a TMP or provisions for contractors to develop a TMP at the most appropriate project phase as applicable to the agency's chosen contracting methodology for the project. A contractor developed TMP must not be implemented before it is approved by the agency.
• The PS&Es must include appropriate pay item provisions for implementing the TMP, either through method or performance based specifications. For method-based specifications individual pay items, lump sum payment, or a combination thereof may be used. For performance based specifications, applicable performance criteria and standards may be used (e.g., safety performance criteria such as number of crashes within the work zone; mobility performance criteria such as travel time through the work zone, delay, queue length, traffic volume; incident response and clearance criteria; work duration criteria).
• The agency and the contractor must each designate a trained person, as specified in section 630.1008(d) of the Rule, at the project-level who has the primary responsibility and sufficient authority for implementing the TMP and other safety and mobility aspects of the project.

  More specific guidance on TMPs is provided in Developing and Implementing Transportation Management Plans for Work Zones. The Guide includes a listing and brief explanation of the different types of TTC, TO, and PI strategies and their characteristics and applicability. This Guide also has a matrix that summarizes the key aspects of the different strategies, which can be used as a quick reference guide. This Guide is available at http://ops.fhwa.dot.gov/wz/resources/final_rule.htm (Accessed 11/18/05).

Step 5 of 5: Advertise and Award Contract

This activity is already performed as part of existing design and construction programs, and is included in this discussion solely for process continuity and integrity.

The activities that generally occur in this step include finalization of ROW issues, finalization of utility and other coordination, submission and approval of fund requests, final review of bid package and project documents by the agency's contracts (bidding and letting) department, contract advertising, addressing contract amendments (if any), conducting pre-bid meetings (if any), and bid review and contract award. The following are some aspects to consider during the contracting process:

• Innovative and alternate contracting approaches (as alternatives to the traditional low-bid process) can help achieve the project objective, accelerate construction, and minimize impacts to road users. Examples include design-build, A+B bidding, lane-rentals, incentive/dis-incentive contracting, and performance-based specifications.
• Timing of the bidding and award process directly impacts the on-time completion of the project and the impacts to road users. For example, if contracts are let in early spring rather than in summer (to late summer), the contractor can take advantage of the spring, summer, and early fall season to complete the work in one construction season as opposed to extending it over two or more construction seasons.
• Timely budgeting and funding are key to ensuring on-time start and completion of work.
• Timely reviews of bids and other contract related issues (amendments, value engineering proposals) can avoid project delays.
• This is a good juncture to coordinate schedules of multiple projects (that may impact each other) by making final adjustments and coordination.
• ROW, utility, and other coordination issues need to be addressed on time.
• Increasingly, agencies are allowing contractors to participate in and provide input to the overall project and construction approach so that their field experience is incorporated into the project before designs, PS&Es, and bids are finalized. Agencies use pre-bid conferences, design competitions, and pre-qualification of contractors to seek contractor input. Such input may help produce designs that are practical to implement, facilitate rational bids, and avoid change orders.

Information on Innovative Contracting is available on the FHWA work zone web site at http://www.ops.fhwa.dot.gov/wz/contracting/index.htm (Accessed 01/18/06). Additional examples of innovative/alternative contracting approaches are available in the FHWA Work Zone Best Practices Guidebook at http://ops.fhwa.dot.gov/wz/practices/best/Default.htm (Accessed 01/18/06).

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