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Project Details
STATUS

Completed

PROJECT NUMBER

19-686, TPF-5(295)

START DATE

01/01/19

END DATE

07/24/20

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, SWZDI
SPONSORS

Iowa Department of Transportation
Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

Co-Principal Investigator
Anuj Sharma

Research Scientist and Leader, REACTOR

About the research

Rear-end crashes are one of the primary crash types in work zones and frequently occur at the back-of-queue (BOQ). Some agencies have utilized back-of-queue warning systems (QWSs), where real-time sensors are located upstream of stopped or slowed traffic, either to actually detect BOQs or monitor conditions to predict BOQ locations. QWSs then provide notifications of traffic conditions to drivers, which ideally lead to lower speeds and drivers being prepared to react to the BOQ, resulting in fewer crashes and conflicts. However, a driver needs to be properly monitoring the roadway environment to receive the warning and, then, needs to be prepared to take the appropriate actions when necessary. In many cases, drivers are distracted and fail to recognize warnings, or they receive the warning but fail to comply with appropriate speeds. As a result, one of the main needs to address BOQ situations is to understand what drivers are doing so that a QWS can get a driver’s attention. Additionally, driver behavior may indicate that other countermeasures, such as speed management, may be as effective as formal QWSs. The research described in this report aims to address this knowledge gap through the following objectives:

  • Identify common types of QWSs
  • Summarize QWSs used in Smart Work Zone Deployment Initiative (SWZDI) states
  • Identify driver behaviors in BOQ scenarios
  • Make recommendations
  • Summarize needs for connected vehicle applications

Safety critical events (SCEs) were evaluated for back-of-queue situations using two different datasets. The first was a set of BOQ SCEs that were reduced from camera image captures at BOQ locations in work zones in Iowa during the 2019 construction season. Analysis of these data indicated speeding, following too closely, and forced merges were the primary characteristics associated with BOQ. The second dataset was an analysis of BOQ events in the second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study (NDS). Analysis of these data indicated that following too closely and glances away from the roadway task of 1 or more seconds were statistically significant.

Project Details
STATUS

In-Progress

PROJECT NUMBER

20-735, TPF-5(438)

START DATE

05/01/20

END DATE

04/30/22

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, SWZDI
SPONSORS

Iowa Department of Transportation
Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
John Shaw

Researcher, CTRE

About the research

In the Work Zone Activity Data Logging Phase I project, state transportation agencies in the SWZDI states and beyond expressed a strong need for better information about the location, extent, and timing of lane closures. More than a dozen use cases for detailed lane closure data were identified and prioritized, such as helping first-responders avoid closures, providing more accurate public information about closure locations and timing, and more efficiently conducing post-construction work zone traffic management effectiveness reviews. Phase I affirmed that the vast majority of state DOTs currently lack the ability to track lane closures at the level of temporal and spatial detail required for these uses. Among the very few agencies that have the technical ability to record this information, the data lacks reliability. Closures on county and municipal routes were seldom, if ever, tracked.

Phase I showed that existing data sources are not sufficient to support the high-priority use cases. For example, although underperforming work zones sometimes show up in traffic management center (TMC) delay data, it is difficult to distinguish work zone delays from delays caused by traffic crashes. Since the exact closure location, timing, and extent are seldom recorded, even agencies with lane closure permitting systems are experiencing great difficulty relating work zone performance to closure characteristics. Moreover, TMC databases provide almost no information about well-performing work zones, making it extraordinarily difficult to pinpoint factors of success.

To address these needs, the Phase I project gathered information about existing work zone data sources, identified relevant standards, and developed a series of sketches that lay out a vision for an easy-to-use lane closure data collection application or website. The goal of this project is to transform these conceptual sketches into a working prototype that generates data in a format that could eventually be integrated with TMC data and other existing data sources to provide a more complete picture of work zone performance.

Project Details
STATUS

Completed

PROJECT NUMBER

19-535

START DATE

01/01/19

END DATE

01/31/20

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Madhav Chitturi

University of Wisconsin, Madison

About the research

Back-of-queue crashes are a significant safety hazard in highway work zones—especially those with intermittent congestion. A number of intelligent transportation systems (ITS) have been developed to provide queue warning, but historically the cost and complexity of these systems have limited their use.

The objective of this project was to design a low-cost queue warning system (QWS) to reduce costs, simplify deployment, and test in the field. The developed low-cost QWS could allow back-of-queue warning signs to be installed wherever queuing is anticipated (even for short-term projects). Modular design of the low-cost QWS will allow the system to be extended as far upstream as necessary to provide ample driver notification in high-, medium-, and low-demand situations.

The sign support system for a low-cost QWS went through several iterations of design in order to find a design that has been crash tested and approved to the Manual for Assessing Safety Hardware (MASH) standards. The final design of the sign support system is based on a non-proprietary support system crash tested by the Texas A&M Transportation Institute. The proposed sign support design for the low-cost QWS has not been able to be field tested for several reasons. The most notable reason is highway agencies are strongly encouraged for safety and liability reasons to only use hardware systems that have successfully completed crash-testing protocols in accordance to the safety standards in the MASH. To date, only a select few sign support systems have been crash tested to MASH criteria, and none with the type of low-cost QWS hardware required for this prototype.

The second reason was the inability to find field test sites on conventional two-lane highways with 55 mph speed limits and the requirement that the equipment be located outside of a clear zone or shielded by protective barriers. Expressway and freeway facilities can’t be used for testing for this design because the Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) requires larger size signs and font letter sizes for the message required on these types of facilities. Therefore, before field testing can be undertaken on highways open to traffic, an investment in funding for crash testing is strongly recommended.

Project Details
STATUS

Completed

PROJECT NUMBER

19-535

START DATE

01/01/19

END DATE

06/03/19

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Yaw Adu-Gyamfi

Assistant Professor

Co-Principal Investigator
Carlos Sun
Co-Principal Investigator
Praveen Edara

University of Missouri-Columbia

About the research

The objective of this research project was to design, develop, and deploy the Smart Work Zone Activity app (SWiZAPP), which is a cross-platform mobile application for collecting, reporting, and posting accurate, real-time, work-zone activity information and status. The app is enabled with functionalities for managing an unlimited number of construction work zones due to its scalable, cloud-based design architecture. It supports work-zone geolocation and mapping via on-board GPS sensors and Google Maps, respectively. Users of the app can post live activities from construction sites by taking snapshots and uploading images, utilizing buttons within the app’s interface to indicate traffic conditions and lane activities, or text messaging via the app. SWiZAPP also enables its users to view both real-time and historical activities of all work zones in the SWZDI states.

This document includes a user manual, as an appendix, to access and use SWiZAPP for work-zone activity monitoring. The user-friendly interface includes standard work-zone procedures and is suitable for use by both department of transportation (DOT) staff and contractors.

The benefits from the successful deployment of SWiZAPP include more accurate and timely work-zone information for work-zone management, traveler information, inspections, contract monitoring, safety analysis, and project coordination.

Project Details
STATUS

In-Progress

PROJECT NUMBER

19-687, TPF-5(295)

START DATE

01/01/19

END DATE

03/31/21

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, SWZDI
SPONSORS

Iowa Department of Transportation
Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
John Shaw

Researcher, CTRE

Co-Principal Investigator
Anuj Sharma

Research Scientist and Leader, REACTOR

Co-Principal Investigator
Christopher Day

Affiliate Researcher

About the research

Although the Manual on Uniform Traffic Control Devices (MUTCD) mandates temporary pedestrian accommodations when permanent facilities are disrupted, in practice, temporary accommodations for pedestrians, people with disabilities, and bicyclists are often inadequate or even nonexistent. Agencies need better tools to manage conflicts between motorized and nonmotorized traffic and reduce the rising number of non-motorist casualties in work zones.

The goal of this project is to investigate several accommodation techniques and develop guidance to assist agencies in applying them. The final list of techniques will be established in consultation with the SWZDI Board of Directors, and could include temporary curb ramps, options for managing vertical transitions, warning signage, and related items.

Project Details
STATUS

Completed

START DATE

12/01/16

END DATE

08/31/18

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Henry Brown

University of Missouri - Columbia

Co-Principal Investigator
Carlos Sun
Co-Principal Investigator
Praveen Edara

University of Missouri-Columbia

Student Researcher(s)
Roozbeh Rahmani

About the research

Engineering practitioners must balance safety and mobility when evaluating different construction phasing alternatives for highway work zones. There is a need for practitioner guidance and practical tools to assess work zone safety impacts as such resources are currently lacking. The objective of the study was to extend a structured safety assessment tool that was previously developed for freeways, expressways, and rural two-lane highways to include other facilities such as arterials, signalized intersections, unsignalized intersections, multi-lane highways, and ramps. Using Missouri data, this study introduces five new crash prediction models for work zones on urban multi-lane highways, arterials, ramps, signalized intersections, and unsignalized intersections. All the work zone models in this report are proposed for the first time. These work zone models are implemented in a user-friendly spreadsheet tool that automatically selects the appropriate model based on user input. The tool predicts crashes by severity, and computes the crash costs for each construction phasing alternative.

Project Details
STATUS

In-Progress

PROJECT NUMBER

TPF-5(295), 18-646

START DATE

01/01/18

END DATE

09/30/20

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, SWZDI
SPONSORS

Iowa Department of Transportation
Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Anuj Sharma

Research Scientist and Leader, REACTOR

Co-Principal Investigator
Shauna Hallmark

Director, InTrans

Co-Principal Investigator
Jennifer Shane

Director, CMAT

About the research

The lack of broadly available information on current and historical work zone activities is a key limiting factor to proactive work zone management. Historically, “passive” data has been used extensively for research and evaluation on the operational and safety impacts of work zones. The sources of such passive data include project plans and letting information, which provide only general guidance as to when and where work is being conducted. In practice, the location, duration, and type of work activity is likely to vary from these initial planning-level projections based upon site-specific issues and unanticipated sources of delay such as adverse weather. Consequently, the use of “active” work zone data is preferred, where agencies collect, disseminate, and maintain detailed work zone information in near real-time. While this type of information is often captured in daily work reports (DWRs), such data is generally not archived in a convenient format. Consequently, there is an urgent need for developing guidance and methods to collect, store, and utilize work zone activity data. This research aims to develop a framework that can be broadly utilized for the effective collection and utilization of active work zone data, allowing for more efficient performance monitoring by state departments of transportation (DOTs), in addition to facilitating more effective research as to the operational and safety impacts of work zones.

Ultimately, the goal is to identify best practices in active work zone data collection and archiving. Based upon these practices, recommendations will be provided as to a prototype application that can be broadly used by state DOTs to effectively archive work zone data.

Project Details
STATUS

Completed

PROJECT NUMBER

18-645, TPF-5(295)

START DATE

04/01/18

END DATE

07/14/20

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, SWZDI
SPONSORS

Iowa Department of Transportation
Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Jing Dong

Transportation Engineer, CTRE

Co-Principal Investigator
Anuj Sharma

Research Scientist and Leader, REACTOR

About the research

This project validated the Highway Capacity Manual (HCM) work zone capacity methodology for urban and rural freeways and provides recommendations for a more accurate estimation of work zone capacity. This study collected data from 16 work zone sites across Iowa in 2018 and 2019. The free flow speeds (FFSs), capacities, and queue discharge rates (QDRs) at these work zones were calculated using the HCM method and compared to field measurements.

For the work zones considered in this study, the key findings are as follows:

  • FFSs estimated using the HCM method had a greater variance than the field-measured values. Under free flowing conditions, Iowans generally drove around the work zone speed limits, while the HCM method predicted a wide range of FFSs.
  • The field-measured prebreakdown capacities and QDRs were significantly lower than the values computed using the HCM method, indicating that traffic breakdown could happen at a much lower flow level than the capacity predicted by the HCM method.
  • With complex work zone configurations, such as narrow lanes, lane shifts, and crossovers, the observed FFS and prebreakdown capacity were significantly lower than typical work zone configurations.
Project Details
STATUS

Completed

START DATE

01/01/17

END DATE

06/01/18

SPONSORS

Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Soyoung Ahn

University of Wisconsin, Madison

Co-Principal Investigator
Madhav Chitturi

University of Wisconsin, Madison

Student Researcher(s)
Anupam Srivastava

About the research

Travel time reliability studies have garnered interest in recent years with researchers and practitioners recognizing reliability as a trait of significant importance to commuters. Presence of work zones can significantly impact the capacity and speeds at the location and consequently impact travel time reliability. This study built a framework for studying impacts of work zone on travel time reliability. The framework covers aspects of work zone selection, evaluation of work zones, derivation of travel time distributions for each work zone, and developing a predictive model for work zone impact on travel time reliability. Work zone and travel time data were collected from 19 freeway and highway work zones across the state of Wisconsin. Supporting hourly traffic counts were collected for the work zones where available. Average travel time trends through a day, travel time distribution, and reliability metrics were studied at each candidate location individually to observe the impacts of the work zone. Reliability measures from across all work zones were combined to study discernible relationships between the change in reliability measures caused due to the work zone and a variety of work zone properties, and predictive regression models were developed to estimate work zone impact on reliability. Due to limitations in the quality and quantity of data available, the regression modeling yielded moderate goodness of fits. A larger dataset and/or availability of detailed work zone information might result in better travel time reliability models. The report presents limitations and findings from the study and informs on quality of data that needs to be collected for future studies on work zone travel time reliability.

Project Details
STATUS

Completed

PROJECT NUMBER

InTrans Project 18-535

START DATE

01/01/17

END DATE

04/01/18

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Smart Work Zone Deployment Initiative

Researchers
Principal Investigator
Madhav Chitturi

University of Wisconsin, Madison

About the research

Roadway lanes are often repositioned to accommodate highway work operations, resulting in a need to alter pavement markings. Even the most effective methods for removing old pavement markings sometimes leave “ghost” markings at the old lane line locations. The ghosts can be quite conspicuous under certain lighting conditions and viewing angles. To address this issue, some international jurisdictions use a special marking color (orange or yellow) to increase the salience of temporary lane lines; this practice appears to have originated in Germany in the 1980s and is now routine in several European countries and the Canadian province of Ontario. Special-color markings have also been used experimentally in Australia, New Zealand, and Quebec. In some jurisdictions the special-color markings override existing markings (such that the old markings are left in place), while other jurisdictions use special-color temporary marking but also attempt to remove old lane lines. The Wisconsin Department of Transportation (WisDOT) experimented with orange work zone marking on a high-volume long-term freeway-to-freeway interchange reconstruction project in Milwaukee; surveys indicate good driver acceptance, but the complex traffic flow characteristics and frequent configuration changes at the site make it difficult to separate the effects of the orange markings from other aspects of the work zone management strategy. To assess the driver behavior aspects of orange markings in a simpler environment, a matched-pair study was conducted on two bridge re-decking projects on I-94 near Oconomowoc, Wisconsin. Evaluation of vehicle positioning and speed data indicated very similar driver behavior with the two colors. Driver surveys and interviews with project field engineers indicated a preference for the orange marking when lateral lane shifts are required. Perhaps the most pragmatic approach is to reserve orange as an emphasis color for specific work zone locations that require difficult driving maneuvers.

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