Figure 31: The Sources of Congestion National Summary - FHWA https://ops.fhwa.dot.gov/aboutus/opstory.htm

Sources of Congestion

Special Events/Other 5% Poor Signal Timing 5%

Bad Weather 15%

Bottlenecks 40% Work Zones 10%

Traffic Incidents 25%

Figure 31: The Sources of Congestion National Summary - FHWA (https://ops.fhwa.dot.gov/aboutus/opstory.htm)

Historically, the Pennsylvania Department of Transportation (PennDOT) has utilized the Work Zone Delay Analysis Workbook to analyze work zone impacts. Recently, the Safety and Traffic Operations in partnership with the Bureau of Maintenance and Operations (BOMO) of PennDOT have decided to use a freeway evaluation software FREEVAL (FREeway EVALuation) to determine highway efficiency under work zone conditions. The FREEVAL, which is based on analytical formulas of the 6th edition of the Highway Capability Manual, is a tool for freeway analysis that could be calibrated and used to assess the possible scenarios of work zone activities in those areas. However, not all work zones are located on the freeways or rural and suburban highways. Therefore, to assist in developing practical plans to evaluate and manage the anticipated type, severity, and extent of work zone impacts on travel time and delay, there is a need to identify appropriate analytical tools and methods for different types of work zones in other (e.g., urban) areas.

7.1 Work Zone Analysis Tools

Federal agencies paid considerable attention to improving the safety and mobility of work zones, mostly after 1991, when the Intermodal Surface Transportation Efficiency Act (ISTEA) mandated a highway work zone safety program to enhance the safety at highway construction sites. Afterward, multiple legislation, regulations, and initiatives in the past two decades have been declared and adopted. These initiatives aimed at enhancing safety, facilitating the management of the mobility impacts of work zones, implementing a policy for the systematic

consideration of work zone impacts on Federal-aid highway projects, and addressing the safety of motorists, pedestrians, and highway construction workers in highway construction work zones (Ye and Al-kaisy, 2010).

Many of these studies considered the impact of work zones in a freeway and urban area. Jiang and Adeli (2003) presented a new freeway work zone traffic delay estimate and total work zone cost optimization model that can be adopted for short- and long-term projects. Khanta (2008) evaluated several traffic simulation modeling packages that are designed specifically for work zone analysis and provided recommendations for traffic agencies to opt for the appropriate software for a specific work zone project. Elefteriadou et al. (2008) reported from Florida Department of Transportation criteria that may impact arterial work zone capacity and improve the used analytical model. The FHWA (Bauer et al., 2019), considered referenced two spreadsheet analysis tools from Michigan and Missouri DOTs for estimating queuing and traffic delays during work zones. A more in-depth summary of these projects can be referenced in Appendix D.

Many of these projects used and recommended different work zone analysis tools (other tools are explained more in detail in Appendix E). Work zone traffic analysis tools are necessary to provide a better view of the condition in the work zone section prior to and during the work zone activities. Several tools have been utilized historically for the analysis of work zones and some of them are still in use today. However, according to the literature, most of the states in the United States are developing appropriate tools based on the situation and requirements of those states. The developed tools are mainly spreadsheet-based analytical tools. In the following, some of the most common tools are mentioned.

 FREEVAL: Freeway evaluation (FREEVAL) is a computerized method intended to diligently execute computations for undersaturated and oversaturated directional highway installations for organizational study. FREEVAL is a powerful tool based on the

Highway Capability Manual for macroscopic freeway research (HCM).  FREEVAL-WZ: FREEVAL-WZ is a version of FREEVAL-2015e which is specifically designed to have a user-friendly environment that applies to work zone study planning level approach. The program aims to have the ability to easily test the results of various work zone conditions and to calculate the effects over time and space of congested times (Trask et al., 2016).  FREEVAL-NC: FREEVAL-NC is the unique variant of FREEVAL for North Carolina intended to have a user-friendly environment that applies an approach to the planning stage for work zones and reliability review of the freeway. Additionally, FREEVAL-NC has access to the segmentation index of the entire North Carolina highway system. The program aims to rapidly test the results of multiple work zone conditions and to measure the effects of congested cycles over time and space with the ability to expand the reliability study over the year (Trask and Aghdashi, 2019).

 FREEVAL-PA: FREEVAL-PA is a tool developed by Pennsylvania DOT that facilitates all forms of freeway research, helping PennDOT workers and contractors to easily gain meaningful information on what traffic effects they will see on every limited-access highway facility in the state from various forms of construction and maintenance programs. The software tool, along with traffic volume and speed data, weather data, elevation data, and a computing engine operated by the HCM, is programmed with the roadway characteristics of each highway section in Pennsylvania to understand the effect of decision-making on capacity. The concept of this tool is from the FREEVAL which has been programmed in North Carolina in the early 1990s (FREEVAL-PA, 2020).  VISSIM: VISSIM as one of the most popular microsimulation tools could be used for freeway analysis especially conducting research for work zone study. VISSIM requires calibration and validation processes before providing meaningful simulation results. With a systematic procedure for calibration of a VISSIM model, capacity, speed, and queue length can be obtained for work zone analysis. One study regarding the calibration of

VISSIM for freeway work zones has concluded that if field speed data is input for desired speed distribution, VISSIM does not reproduce the data for single-lane freeway work zones (Kan et al., 2014).

7.2 Effect of Work Zones on Arterial Networks

Construction zones can be broken into those in an urban, arterial setting or freeways. These are very different situations and require separate consideration. Since a greater impact of early opening will be experienced by urban roads, this category will be considered and reported in this report. An alternate analysis of freeways can be referenced in Task 4 of this project.

7.2.1 Methodology

To analyze the work-zone impact on the user delay costs of an urban arterial network, a subarea of the Pittsburgh Downtown was used (Figure 32). The network was modeled in VISSIM microsimulation environment. The model consists of 28 signalized intersections and about 550 Origin-Destination (OD) routes. The model was developed for the City of Pittsburgh, for the PM peak hour, and was given to University of Pittsburgh researchers. Considering that the VISSIM model was developed only for the busiest hour of a day, it was necessary to develop a methodology for adjusting the resulting work-zone outputs for the remaining hours of the day.