A survey of work zone practices and validation of HCM work zone capacity model
Raju Thapa, Louisiana Department of Transportation and DevelopmentShow Abstract
Julius Codjoe (Julius.Codjoe@la.gov), Louisiana Department of Transportation and Development
Yaa Amanua, Kittelson & Associates, Inc. (KAI)
Capacity at work zones is one of the major factors affecting queueing at work zones. Different states within the United States (US) use their own methodology in determining work zone capacities and when to implement lane closures at work zones. The objective of this study was two-fold: first, to provide a synthesis of work zone lane closure procedures practiced by the various Departments of Transportation (DOT) nationwide; and secondly, to validate the Highway Capacity Manual 6 th Edition’s (HCM 6) work zone capacity model using field collected data in the state of Louisiana. The first objective was met by administering a survey to DOTs nationwide. The survey revealed that half of the states that responded to the survey require minimum capacity for short term work zone lane closures with minimum capacity ranging from 1,100 to 1,900 pcphpl. In addition, most of the states reported implementing consistent policies across various district offices. The survey findings provide a good source of information on queue analysis and work zone lane closure policies adopted across different DOTs. The second objective was met by collecting traffic flow data from ten work zone sites within the state of Louisiana and validating the capacity model in the HCM 6. Results showed HCM 6 model slightly overestimating the average field observed capacity by 6%. In the absence of local data, the HCM 6 model provides a great tool to estimate work zone capacities in Louisiana.
Investigating the Performance of Snowplowable Reflective Pavement Markers in Illinois
Carmine Dwyer, Applied Research Associates, Inc. (ARA)Show Abstract
Kelly Morse, Illinois Department of Transportation
Kyle Armstrong, Illinois Department of Transportation
The Illinois Department of Transportation (IDOT) investigated the installation and performance of snowplowable reflective pavement markers (SRPMs) to determine optimum pavement marker solutions and policies for roadways in Illinois. The research evaluated the performance of five traditional cast-iron and two plastic SRPMs on test sections of both asphalt and concrete pavements. All five iron markers and one plastic marker had a traditional raised face for the reflective lens, and the other plastic marker was completely recessed in the pavement. Analysis included 1) comparisons of casting design, casting material, and groove design; 2) assessments on how each factor contributed to pavement marker performance; and 3) development of crash modification factors (CMFs) for quantifying any safety improvement from SRPM use. Due to a lack of crash data, the CMF development was limited to freeway sections with six or more lanes (combined directions). The results of the SRPM performance evaluation and CMF development were used to provide recommended updates to IDOT’s guidelines for the use of raised pavement markers and to IDOT’s raised reflective pavement marker inspection policy. This paper presents the SRPM performance assessment methods and results.
Deploying and Integrating Smart Devices to Improve Work Zone Data for WZDx
Skylar Knickerbocker (email@example.com), Iowa State UniversityShow Abstract
Varsha Ravichandra-Mouli, Iowa State University
Archana Venkatachalapathy, Iowa State University
Connected temporary traffic control devices that provide their location and status are a new tool that Infrastructure Owner and Operators (IOOs) can begin to use to improve the accuracy of work zone data. By improving work zone data, better information can be provided to the public. Publishing this data through the WZDx (Work zone data exchange) aims to improve safety by notifying drivers and vehicles of where verified work zones are located. Connected devices such as smart arrow boards and connected cones have continued to grow in the market but little has been done to determine the best method of integrating these devices into the DOTs systems. An approach is presented which integrates deployed smart arrow boards to indicate actual conditions as part of a planned work zone by leveraging a DOTs linear referencing system. This method does not require any additional efforts of field staff and improves the location and temporal accuracy of work zone information as part of a WZDx. This system when deployed successfully showed that smart arrow boards could be automatically associated to a work zone in controlled test scenarios as well as in a limited sample under real-world conditions. In real-world conditions, contractors did not need to provide any additional information to associate the smart arrow board to the 511 work zone event. The effort represents a starting point for how connected temporary traffic control devices can be integrated into the DOTs system to improve work zone data accuracy.
A Citywide Location-Allocation Framework for Driver Feedback Signs: Optimizing Safety and Coverage of Vulnerable Road Users
Mingjian Wu (firstname.lastname@example.org), University of AlbertaShow Abstract
Tae J. Kwon, University of Alberta
Karim El-Basyouny, University of Alberta
Driver feedback signs (DFSs) are being adopted by municipalities around the world in ever-increasing numbers, as they are a low-cost intervention tool that improves drivers’ compliance with speeds. Previous efforts have shown the safety impact of DFS on reducing collisions on urban roadways. However, research is still needed on developing a location-allocation framework to determine the optimal implementation strategies for DFS placement. Hence, the main aim of this paper is to formulate a location-allocation optimization problem with an objective of reducing vehicular collisions while enhancing spatial coverage for vulnerable road users and facilities. The greedy algorithm was employed to solve the proposed optimization problem for two distinct planning scenarios, namely, an all-new and expansion scenario. The all-new scenario represents cases where all existing DFSs are moved to optimal locations whereas the expansion scenario takes an existing DFS system and recommends where new DFS units should be installed. The real-world case study of the City of Edmonton was used to illustrate the distinct features of the proposed method. The findings revealed that the DFS implementation strategies provide decision-makers with the freedom to optimize their city-wide DFS networks by considering both the safety effectiveness and the coverage of vulnerable road users/facilities.
Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps based on Sign Location, Interchange Type, and Time of Day
Md Shakir Mahmud, Michigan State UniversityShow Abstract
Matthew Motz, Michigan State University
Travis Holpuch, Michigan State University
Anthony Ingle, Michigan State University
Timothy Gates (email@example.com), Michigan State University
Peter Savolainen, Michigan State University
Roadway segments that include horizontal curves experience a disproportionate number of crashes compared to straight segments. Many of these crashes are lane departure-related, and excessive speed is often a contributing factor. One particularly vulnerable area for such crashes is freeway interchange ramps, which require a substantial reduction in speed to be safely negotiated. While dynamic speed feedback signs (DSFS) have been found to be an effective speed and crash reduction countermeasure at horizontal curves, the use of such signs on freeway interchange ramps has been limited nationwide. Consequently, the effectiveness of DSFS as a speed reduction countermeasure in such settings has remained largely untested. A before-and-after field evaluation was performed at three freeway exit ramps to assess the impacts of a DSFS on driver speed selection and braking characteristics while approaching and entering the ramp curves. The effectiveness of the feedback sign was tested across various conditions, including sign location, interchange type, time of day, light condition, and vehicle type. In general, the greatest benefits to driver behavior were achieved with the DSFS positioned at the point of curvature, during which curve entry speeds were reduced by approximately 2 mph compared to the pre-DSFS condition. These findings were consistent between the system- and service-interchanges and across all vehicle types. The DSFS was also found to be most effective during daytime off-peak periods compared to peak periods and at night. Based on the study findings, the continued use of DSFS as a speed reduction treatment at freeway exit ramps is recommended.
INTRODUCING A NEW APPARATUS FOR DESIGNATING TWO-LANE HIGHWAY PASSING AND NO-PASSING ZONES
Ahmed Farid, University of WyomingShow Abstract
Zephaniah Connell, University of Wyoming
James Mock, University of Wyoming
Suresh Muknahallipatna, University of Wyoming
Khaled Ksaibati (firstname.lastname@example.org), University of Wyoming
Two-lane highways constitute a large proportion of the nation’s highways. An essential component needed for the design of two-lane highways is the passing sight distance (PSD). Otherwise, insufficient PSDs lead to passing related crashes and hence no-passing zones ought to be marked. There are several methods employed for measuring the PSD. This research involves the development of a new apparatus of the two-vehicle method, a field based method, to replace the defunct apparatus used by the Wyoming Department of Transportation (WYDOT). This research also contributes to the two-lane highway literature by addressing the shortcomings of a recent study involving the implementation of the two-vehicle method. Furthermore, other PSD studies were aimed at estimating the PSD using remote-based data such as global positioning satellite (GPS) data and light detection and ranging (LiDAR) data instead of field data. The apparatus, developed for this research, was tested on both directions of two two-lane highway segments near Laramie, Wyoming. The segments were of WY-210 and US-287. The tests were conducted and the outputted passing/no-passing zone plans were compared to those of WYDOT. According to the comparison, the results were in-line with WYDOT’s. This research lays the foundation for a future study involving the development of a cutting-edge prototype of the two-vehicle method. It is designed to automate a multitude of tasks needed to implement the method and achieve more accurate results.
The Effect of Changing the Color of A Traffic Control Device on Driver Behavior and Perception across Different Age Groups
Hatem Abou-Senna (email@example.com), University of Central FloridaShow Abstract
Mohamed El-Agroudy, VHB
Mustapha Mouloua, University of Central Florida
Essam Radwan, University of Central Florida
The use of express-lanes (ELs) in freeway traffic management has seen increasing popularity throughout the US, particularly in Florida. These lanes aim at making the most efficient transportation system management and operations (TSM&O) tool to provide a more reliable trip. An important component of ELs is the channelizing devices used to delineate the separation between the ELs and the general-purpose-lane (GPL). With the upcoming changes to the Manual on Uniform Traffic Control Devices (MUTCD), this study provided an opportunity to recommend changes affecting safety and efficiency on a nationwide level. It was important to understand the impacts to driver perception and performance in response to the color of the EL delineators. It was also valuable to understand the differences between demographics in responding to delineators colors under different driving conditions. The driving simulator was used to test the responses of several demographic groups to changes in marker color and driving conditions. Furthermore, participants were tested for several factors relevant to driving performance including visual tests and subjective responses to the changes in colors and driving conditions. Impacts to driver perception was observed via eye-tracking technology with changes to time of day, visibility, traffic density, roadway surface type, and, crucially, color of the delineating devices. The analyses concluded that white, was the optimal and most significant color for notice of delineators across the majority of subjective and performance measures, followed by yellow color, with black being the least desirable.
Queue analysis at work zones: An analysis from field collected data
Julius Codjoe (Julius.Codjoe@la.gov), Louisiana Department of Transportation and DevelopmentShow Abstract
Raju Thapa, Louisiana Department of Transportation and Development
Elisabeta Mitran, Louisiana Department of Transportation and Development
Estimation of capacity of work zones is vital to manage the possibility of traffic flows over exceeding capacity and resulting in unbearable queues during work zone lane closures. A plethora of research papers studied several ways to estimate work zone capacity, with Highway Capacity Manual (HCM) having its own methodology to estimate capacity based on various site characteristics. However, HCM always recommend validating its model with local data to reflect actual driving behavior of the region. This study considered work zone capacity as a function of queue discharge rate (QDR), defined as 15-min average flow rate immediately after the breakdown, also known as a post-breakdown flow rate. By collecting data from ten different work zones within the state of Louisiana, the study estimated QDR and its corresponding duration at all the breakdowns. This study found an average QDR of 1,664 pcphpl and an associated queue with average duration of 120 minutes. The result from ANOVA showed that average QDR across all the sites were not significantly different. The QDR prediction model revealed that right lane closed and work zone on linear roadways significantly increased the discharge rate. However, the presence of nearby exit ramps, daytime scenarios, and increase in the speed ratio and truck percentages were found to decrease the discharge rate. A separate model for the duration of queue or breakdown found time of day, change in the speed ratio, presence of entry ramp, location of work zones, and AADT of the roadway as significant variables.
Effectiveness of Warning Piles on Driving Behavior on the Curve of Low-grade Highway
Yibing Liu, Beijing University of TechnologyShow Abstract
Xiaohua Zhao, Beijing University of Technology
Jia Li (firstname.lastname@example.org), Beijing University of Technology
Yang Bian, Beijing University of Technology
Jianming Ma, Texas Department of Transportation
In order to develop a scientific and practicable guideline for implementing warning piles on Chinese low-grade highways, it is necessary to study the effect of warning piles on driving performance in different road alignment and environment. Based on a driving simulator, this paper the effect of unilateral and bilateral warning piles on vehicle speed and lateral position on a two-lane rural highway curve with different road geometries. The results showed a significant effect of bilateral warning piles on speed control, and this function became more obvious with the radius decreased and superelevation increased. In sharp curves, vehicles’ speed rapid increased in the second half of the curve, and the bilateral warning piles could significantly control the increase of the speed to keep away from the danger. Meanwhile, the effect of bilateral warning piles on keeping vehicles staying in a more safety lane position was also statistically significant at the second half of the curve. With the radius decreased and superelevation increased, the value of the maximum lateral position got increased. The bilateral warning piles could reduce the lateral position to keep the vehicle in a stable track. Besides, the bilateral warning piles could keep a better performance at night. This paper studied both the unilateral and bilateral warning piles’ effect on driving behavior in different road geometries, the study result could provide a theoretical basis for the engineering application of warning piles.
Work Zone Intrusion Alarm Systems - Evaluation and Practical Implementation Guide for Work Zone Traffic Plans
Ghazan Khan (email@example.com), California State University, SacramentoShow Abstract
Kevan Shafizadeh, California State University, Sacramento
The main goal of this research was to evaluate the effectiveness of work zone intrusion alarm (WZIA) systems and provide recommendations on the effectiveness and practicality of implementing such systems in a work zone. Three WZIA systems were selected for evaluation. A detailed evaluation framework was developed to assess the performance of each system and understand their capabilities, issues, and limitations. Pilot testing was conducted, resulting in some issues identified during the literature review, and other new issues and unexpected outcomes. Supplemental testing was subsequently conducted to better assess the systems’ capabilities and strengthen recommendations. The final results showed that the Worker Alert System (WAS) performed well, with certain limitations and differences from the manufacturer’s specifications observed. The SonoBlaster system encountered several issues and limitations, most of which could not be resolved or corrected. The Intellicone system’s intermittent issues observed during the pilot testing were resolved after extensive supplemental testing and consultation with the manufacturer, and subsequent trials were successful. Additionally, supplemental plans to the T-13 Caltrans standard work zone traffic control plan were developed. These supplemental plans detail the recommended deployment location, range distances, and setup of the Intellicone and WAS. Implementation of the Intellicone and WAS in California work zones could provide additional safety benefits, supplementing existing safety practices for the benefit of work zone workers and reducing work zone fatalities.
Development of Cost-Effective Restriping Strategies Using Standard Width and Wide Waterborne Paints on Asphalt Pavements in Hot and Humid Climates
Momen Mousa, Louisiana State UniversityShow Abstract
Marwa Hassan (firstname.lastname@example.org), Louisiana State University
Paul Carlson, Road Infrastructure, Inc.
Jason Davis, Louisiana Department of Transportation and Development
Saleh Mousa, Louisiana State University
In Louisiana, most districts restripe their roadways using waterborne paints every other year; this strategy is questionable in terms of efficiency and economy. Meanwhile, previous studies showed substantial variability in the paint service life throughout the United States ranging between 0.25 and 6.2 years. Shortcomings in modeling the retroreflectivity of waterborne paints appear to significantly contribute to these variations as several studies predicted these values using degradation curves with a coefficient of determination (R 2 ) as low as 0.1. Therefore, the objective of this study was to develop new cost-effective restriping strategies using 4-inch (15-mil thickness) and 6-inch (25-mil thickness) wide waterborne paints when applied on asphalt pavements in hot and humid climates. To achieve this objective, National Transportation Product Evaluation Program (NTPEP) data were collected and analyzed to evaluate the field performance of waterborne paints commonly used in Southern United States and to develop a decision-making model that may be used by transportation agencies to predict when to restripe their roadways. Results indicated that 4-inch wide standard paints exhibited service life up to four years depending on the line color, traffic and initial retroreflectivity, while 4-inch wide high-build paints had a service life of at least three years. Based on a life-cycle cost analysis, it was concluded that LaDOTD could restripe their district roads every three years instead of the current two-year period using the same product (4-inch or 6-inch wide) saving about $4.3 or $1.9 million, respectively, every year when restriping a 5,000-mile network.
Influence of Stop Lines on Driver Behavior at Two-Way Stop Controlled Intersections
Melissa Duhn, University of Minnesota, Twin CitiesShow Abstract
John Hourdos, University of Minnesota, Twin Cities
Andrew Loutfi, University of Minnesota
Peter Dirks, Cook County Department of Transportation and Highways
Stop lines are ubiquitous, but do they really influence driver behavior? Prior to this project, no long term studies on intersection safety with stop lines had been completed. This observational study was developed to determine if stop lines have an effect on driver behavior at intersections, and look at where drivers are stopping both before and after the installation of a stop line. Video was collected at 16 different intersections before and after a stop line was painted, and results were analyzed both qualitatively and quantitatively. The observational study and regression analysis of observational results all show that stop lines do not have a significant impact on driver behavior or intersection safety, but other factors like site geometry and pedestrian presence can. Implications for practice include carefully examining sight distance at the intended stopping point to ensure drivers will have adequate sight distance in both directions; if sight distance is not adequate, moving the intended stopping location or reconsidering if the intersection should be signed as yield or uncontrolled may result in better driver compliance and safety.
Investigating the Effectiveness of Stop Lines in Improving Safety at Two-Way Stop Controlled Intersections
Melissa Duhn, University of Minnesota, Twin CitiesShow Abstract
Gary Davis, University of Minnesota, Twin Cities
John Hourdos, University of Minnesota, Twin Cities
Peter Dirks, Cook County Department of Transportation and Highways
Andrew Loutfi, University of Minnesota
Stop lines are ubiquitous, but do they really impact intersection safety? Prior to this project, no long term studies on intersection safety with stop lines had been completed. This safety study was developed to estimate the effect, if any, stop lines have on intersection safety. Following established Highway Safety Manual (HSM) procedures, the study utilized historical crash records from all NAWSC intersections in five Twin Cities metropolitan areas’ stop-controlled intersections to quantify the effect and significance of stop lines on crash occurrence while controlling for other variables like AADT, sight distance quality, speed limits, and other. The safety study showed that stop lines do not have a significant impact on driver behavior or intersection safety, but other factors like site geometry and pedestrian presence can have an impact. Implications for practice include carefully examining sight distance at the intended stopping point to ensure drivers will have adequate sight distance in both directions; considering adaptions when sight distance is not adequate, such as moving the intended stopping location or reconsidering if the intersection should be signed – stop or yield – or uncontrolled may yield better driver compliance and safety.
Safety Impact of Connected Vehicles on Driver Behavior in Rural Work Zones under Foggy Weather Conditions
Eric Adomah, University of WyomingShow Abstract
Arash Khoda Bakhshi, University of Wyoming
Mohamed Ahmed, University of Wyoming
Work zone safety is one of the paramount goals of the safety community. The safety concerns in work zones might be exacerbated under foggy conditions, as an exogenous factor, contributing to high driver behavior variability. In line with the Connected Vehicle (CV) Pilot Deployment Program on Interstate-80 (I-80) in Wyoming, this study investigates the safety benefits of CV Work Zone Warning (WZW) application on driver behavior during foggy weather conditions. A work zone was simulated using VISSIM under four sequential areas, including the advance warning, transition, activity, and termination area. The effect of increased drivers' situational awareness under the impact of WZW was calibrated in VISSIM based on the results of a high-fidelity Driving Simulator experiment.Various Surrogate Measures of Safety (SMoS), including Time-To-Collision (TTC), Modified Deceleration Rate to Avoid Crash (MDRAC), Time Exposed Time-to-collision (TET), and Time-Integrated Time-to-collision (TIT), were employed to quantify the safety performance of CVs under varying CVs Market Penetration Rates (MPRs). According to the results of TTC and MDRAC, it was found that the increase in CV-MPR enhances the safety performance of the work zone area. Findings showed that, under foggy weather conditions, the advance warning area had the highest TIT and TET values. Furthermore, it was revealed that an increase in MPR up to 60% on I-80 would reduce mean speed and standard deviation of speed at each of the work zone areas, leading to more speed harmonization and minimizing crash risk in work zones.
IMPACT OF ADVERSE WINTRY CONDITIONS ON THE EFFECTIVENESS OF CENTERLINE RUMBLE STRIPS - A CASE STUDY OF WYOMING AND COLORADO USING BEFORE-AFTER EMPIRICAL BAYES DESIGN
Irfan Ahmed, University of WyomingShow Abstract
Mohamed Ahmed, University of Wyoming
Head-on crashes contribute towards the highest share of multi-vehicle crashes despite being a small percentage of overall crashes. Over the years, centerline rumbles strips (CLRS) have emerged as a cost-effective countermeasure to prevent head-on or cross-over-the-centerline crashes. The overall safety benefits of CLRS is well-proven in the literature. However, there are some anecdotal evidence of its reduced effectiveness during adverse wintry conditions. Since there was no quantitative research in this matter, this study aims to fill that gap. The overall safety effectiveness of CLRS in Wyoming and Colorado was quantified in this study by season; summer and winter. A before-after Empirical Bayes method was chosen to develop Crash Modification Factors (CMFs). Safety performance functions were developed to predict annual, summer, and winter Total, Property Damage Only, Fatal and Injury, as well as Target crashes. Expected crash reductions in Wyoming were found to be between 23% and 72% and those in Colorado ranged between 41% and 84%. The higher percentage of expected crash reductions were associated with the target crashes, head-on crashes. Results show that the CMFs obtained for Wyoming are higher than the ones for Colorado, which can be attributed to the winter maintenance efforts of the jurisdictions. Furthermore, winter CMFs were found to be higher than the summer CMFs suggesting the impact of accumulated snow or ice on reduced depth accompanied by reduced noise and vibration levels. Active and timely winter maintenance efforts are key to keep the CLRS free of snow or ice, thereby not reducing its effectiveness.
Enhancing Construction Truck Safety at Work Zones: A Microscopic Traffic Simulation Study
Zijin Wang, University of Central FloridaShow Abstract
Jaeyoung Lee, Central South University
Highway work zones are generally considered dangerous, causing hundreds of fatalities every year. One significant task of work zone safety issue is how to manage construction trucks egress from work zones. Previous studies have been conducted to improve truck egress safety, yet few engineering countermeasures have been proposed, which might have a significant improvement of safety at highway work zones. In this study, a microsimulation network of highway work zone interval is built and calibrated using field data in Florida. The impact of work zone truck egress speed is investigated based on the simulation model, and the results indicates that it is significant to provide a sufficient truck acceleration lane inside the work zone. Afterwards, the truck egress system (TES) that aims at providing a sufficient gap for trucks to merging into when egress from the work zone is developed. Then, the truck egress process is simulated with different settings of TES. The results show that the introduction of TES improves the safety, and the best settings for different traffic volume scenarios are selected. The findings of this study could help transportation engineers or decision makers understand the effect of the TES before implementing it in the real field.
Safety Effects of Work Zone Advisory Systems under the Intelligent Connected Vehicle Environment: A Microsimulation Approach
Suyi Mao, Central South UniversityShow Abstract
Guiming Xiao, Central South University
Jaeyoung Lee, Central South University
Ling Wang, Tongji University
Zijin Wang, University of Central Florida
Helai Huang, Central South University
The maintenance is essential to keep good roadway conditions. Nevertheless, it is inevitable that crash risks increase in work zones. There have been many efforts to minimize crash risks in the work zones by installing conspicuous orange colored signs, imposing doubling fines, providing work zone information by fixed and portable dynamic message signs (DMSs), etc. Still, work-zone related crashes are considered as a serious issue. In this study, we investigated the safety effects of work zone advisory systems. The traditional system includes a dynamic message signs while the advanced system includes an in-vehicle work zone warning application under the connected vehicle (CV) environment. A comparative analysis was conducted by designing microsimulation experiments. The results indicate that the CV-based warning system outperforms the DMS. From this study, the optimal distances of placing a dynamic message sign varies according to different traffic conditions. Nevertheless, negative influence of excessive distance DMS placed from the work zone would be more obvious when there is heavier traffic volume. Thus, it is recommended that the optimal distance DMS placed from the work zone should be shortened if there is a traffic congestion. It was also revealed that higher market penetration rate of CVs will lead to safer network under good traffic conditions.
The Safety Effect of Traffic Signs for Median Openings on One-Side-Widened Freeways
Xu Wang (email@example.com), Shandong UniversityShow Abstract
Peiyu Jiang, Shandong University
Yue Cao, Wuhan University
Nengchao Lyu, Wuhan University
Lei Niu, Shandong Transportation Research Institute
Highway networks deteriorate as a result of increasing traffic and aging infrastructure. Aging infrastructure requires timely maintenance, expansions and upgrades. Due to limited project budgets, however, highways are sometimes widened on only one side, and openings are configured on existing medians, rather than existing medians being removed altogether, particularly in developing countries. The additional safety risks and mobility problems associated with this uncommon road configuration call for extra attention when designing, laying out and placing traffic signs around median openings. The safety effect of these signs must be evaluated before implementation. Thus, this study aims to develop a thorough understanding of sign configuration to improve the safety of median openings. Different sign configuration plans were tested through driving simulation of a section of the Binlai Freeway in Shandong, China. The data collected on the different driving performance and workload measures determined the safety benefits brought by different signs. The results show that the sign configuration with the best safety performance must be determined considering the unique traffic flow environment at each opening. The findings from this study can effectively inform open-median traffic control on one-side-widened highways.
On Consistency in the Selection of Countermeasure at Mid-block Crosswalks
Balaji Ponnu, Ohio State UniversityShow Abstract
Marshall King, Ohio State University
Beth Snoke, Ohio State University
There are two most commonly used methods identified in the literature for the choice of countermeasure at mid-block crosswalks namely the pedestrian crash safety method, and the pedestrian level of service method. Agencies typically use one of the two methods, leading to an inconsistency in the recommended countermeasure for the same crosswalk. The variation could lead to a large difference in the recommended treatments e.g., a crosswalk that warrants a full signal in the first method might warrant only a marked crosswalk in the second. This research collects empirical data from ten different mid-block crosswalks across the Ohio State University campus in Columbus, Ohio and finds that the two methods lead to significantly different treatments for 70% of the crosswalks. The lack of consistency in the existing crosswalk countermeasure choice procedures is an important finding since deciding countermeasures based on pedestrian crashes is not necessarily optimal for reducing pedestrian delays and vice versa. Then, at a given crosswalk, considering the stricter countermeasure from among the two methods and the existing control present, this work develops a procedure to arrive at a recommended countermeasure. Agencies could use this procedure considering both the methods to arrive at a countermeasure rather than just using only one of the methods until a comprehensive crosswalk countermeasure choice procedure combining both is developed in the future. The need for including other potential factors such as vehicle delays in the comprehensive procedure is also emphasized.
A Multiple Correspondence Approach to Identify Contributing Factors Related to Work Zone Crashes
Parisa Hosseini, Rowan UniversityShow Abstract
Mohammad Jalayer, Rowan University
Subasish Das, Texas A&M University
Work zones are perilous locations that can interrupt normal traffic flow and cause safety problems for both drivers and construction workers. Each year, approximately 700 fatalities and 40,000 injuries are reported related to work zone crashes in the United States. As such, further in-depth investigation of characteristics of work zone-related crashes has been of long-standing interest in traffic safety. The main objective of this study is to investigate the key factors contributed to work zone crashes by using Multiple Correspondence Analysis (MCA). MCA is an extension of the Corresponding Analysis (CA) method, which identifies the pattern association between various categorical variables. In this study, a total of 8,232 work zone-related crash data in New Jersey from 2016 to 2018 were obtained and analyzed. Results showed factors such as the number of vehicles involved, lighting conditions, time of the crash, and crash type are the most significant contributing factors associated with work zone crashes. The findings of this study can help transportation professionals select the most efficient and effective countermeasures to mitigate the frequency and severity of work zone-related crashes.
Identification and Characterization of Mobile Work Zones using Floating Car Data
Weimin Huang, HEREShow Abstract
Yildirim Dülgar, Mercedes-Benz AG
Hubert Rehborn, Mercedes-Benz AG
Bruce Bernhardt, HERE
This paper describes a methodology for the identifying active mobile roadworks zones based on detecting the forward forming shockwave associated with the congestion front with the use of vehicle probe data. Two examples are provided and characterized where the activity is verified by independent means for ground truth. Additional shockwave transitions determined to be a wide-moving jam and a mega jam associated with the mobile roadworks activities within the congested regions are also identified and characterized as well. The algorithms to determine the propagation rate of the transitions are presented and compared to traffic theory. The impact on vehicle travel times during the presence of the mobile roadworks are determined.
Work-Zone Crash Severity Analysis: Development and Use of the Joint Distribution of Crash-Related Variables
Seyed Hooman Ghasemi, Washington State UniversityShow Abstract
Ji Yun Lee, Washington State University
Mohammad Jalayer, Rowan University
Parisa Hosseini, Rowan University
Pooyan Khajehshahzanian, Amirkabir University of Technology
Over the past few decades, work-zone crashes have been perceived as one of the pivotal concerns in improving roadway safety. Each year, traffic accidents in construction and maintenance zones result in hundreds of fatalities and thousands of injuries, and accordingly, many studies have investigated the statistical properties of work-zone crashes as part of efforts to reduce the numbers of fatalities and injuries. The primary goal of this study is to investigate the combined effects of various driving conditions on work-zone crash severity so that maximum speed in construction zone can be adjusted to meet the pre-defined safety. To this end, the paper first filters and clusters work-zone crash data and develops the marginal probability density functions of various exogenous and endogenous variables. In this study, vehicle speed and driving conditions (e.g., road surface, light and weather conditions) are identified as the key independent variables in crash severity analysis. Finally, the distributions of total work-zone crash cost conditioned on vehicle speed and various driving conditions are developed to specify the allowable speed limit of vehicles with the goal of reducing the crash costs. The proposed cost-based crash severity analysis can be further utilized in an online speed limit system considering various driving conditions.
Impact of risk factors on work zone crashes using logistic models and Random Forest
Huthaifa Ashqar, Booz Allen Hamilton, Inc.Show Abstract
Qadri Shaheen, Michigan Department of Transportation
Suleiman Ashur, Eastern Michigan University
Hesham Rakha, Virginia Polytechnic Institute and State University (Virginia Tech)
Work zone safety is influenced by many risk factors. Consequently, a comprehensive knowledge of the risk factors identified from crash data analysis becomes critical in reducing risk levels and preventing severe crashes in work zones. This study focuses on the 2016 severe crashes that occurred in the State of Michigan (USA) in work zones along highway I-94. The study identified the risk factors from a wide range of crash variables characterizing environmental, driver, crash and road-related variables. The impact of these risk factors on crash severity was investigated using frequency analyses, logistic regression statistics, and a machine learning Random Forest (RF) algorithm. It is anticipated that the findings of this study will help traffic engineers and departments of transportation in developing work zone countermeasures to improve safety and reduce the crash risk. It was found that some of these factors could be overlooked when designing and devising work zone traffic control plans. Results indicate, for example, the need for appropriate traffic control mechanisms such as harmonizing the speed of vehicles before approaching work zones, the need to provide illumination at specific locations of the work zone, and the need to establish frequent public education programs, flyers, and ads targeting high-risk driver groups. Moreover, the Random Forest algorithm was found to be efficient, promising, and recommended in crash data analysis, specifically, when the data sample size is small.
Analysis of Work Zone Driver Merge Behavior and Merge Location Decision Using Work Zone Camera Images
Cibi Pranav, Georgia Institute of Technology (Georgia Tech)Show Abstract
Yichang Tsai, Georgia Institute of Technology (Georgia Tech)
Work zone merge behavior is a pressing safety concern. This paper aims to 1) develop a methodology to study the impact of different roadway, traffic, and vehicle factors on real-world work zone driver merge behaviors, especially merge decision behavior (early or late merge) using camera images, and 2) reveal the real-world impact of different roadway geometry and traffic scenarios on driver merge decision behavior. The developed methodology consists of three modules: 1) the field test design module that includes scenario-based field data collection, zone-based work zone division for grouping driver merge behavior, and a factor-based case study to quantitatively (zone-based) analyze the impacts of different factors on driver merge behaviors, 2) the data extraction module for extracting traffic and driver behavior data, including traffic density, vehicle data, and zone-based merge location data from camera images, and 3) the data analysis module for computing and plotting the proportion of driver merges decisions in each zone to analyze the zone-based merge location decisions. Results from work zone camera data collected on Georgia Interstate-95, U.S.A, reveal that higher percentage of car drivers merge late under high traffic density condition and when a curved roadway geometry precedes the work zone. However, majority of truck drivers typically merge early compared to car drivers regardless of roadway geometry and traffic conditions. Based on the observed behaviors, transportation agencies can optimize work zone traffic control setups to improve work zone safety and mobility.
Fast Safety Assessment and Correction Framework for Maintenance Work Zones
Zhepu Xu, Shanghai Institute of TechnologyShow Abstract
Qun Yang, Tongji University
A framework is proposed to assess the safety of maintenance work zones in a timely manner, show whether there are safety hazards, whether adjustments need to be made and how to adjust it. By means of advanced data acquisition technologies such as multi video detection and portable device based naturalistic driving, the microscopic vehicle behaviour data can be collected. Based on this data, a method for expressing and displaying the distribution of unsafe vehicle behaviour is used to show whether safety hazards exist. Using Vissim, the impacts of the length and speed limit of the warning area, the length and type of the upstream transition area and the length of the work area of the maintenance work zone on the distribution of unsafe vehicle behaviour are simulated to establish the safety correction matrix, which can tell maintenance departments the direction of adjustment when safety hazards exist in maintenance work zones.
Agile Work Zone Management Based on Probe Traffic Data
Jairaj Desai, Purdue UniversityShow Abstract
Steven Rogers, Purdue University
Woosung Kim, Purdue University
Howell Li, Purdue University
Deborah Horton, Purdue University
James Poturalski, Indiana Department of Transportation
Darcy Bullock, Purdue University
Peak period lane closures can result in significant queueing on major interstates. As a result, many state agencies have a lane closure policy in place based upon historical time of day and day of week traffic volumes. The COVID-19 pandemic resulted in a significant reduction in traffic volumes in Indiana during the March-May 2020 period. In some periods, traffic volume reductions were over 35%. During this period, the Indiana Department of Transportation (INDOT) implemented an agile lane closure policy based upon observed volumes and monitored those exceptions using commercial probe data. This paper reports on the analysis of 11 lane closure exceptions on 4 interstate roadways (I-65, I-69, I-70 and I-265) across Indiana, lasting from 36 days to 41 days. Congestion comparisons have been made for each of the 11 exceptions for the same time period in 2020 and 2019. Even with the lane closures exceptions, the study found 10 of 11 sections actually had fewer mile-hours of congestion and the total mile-hours of congestion for all 11 sections was reduced from 1281 mile-hours in 2019 to 244 mile-hours in 2020. Overall, crashes decreased from 127 in 2019 to 70 in 2020. Year-over-year congestion statistics and crash counts for these exceptions demonstrated significant opportunities for agile work zone lane closure practices when they are coupled with close monitoring of crash and congestion data.
Are Work Zones and Connected Automated Vehicles Ready for a Harmonious Coexistence? A Scoping Review and Research Agenda
Amjad Dehman (firstname.lastname@example.org), Ryerson UniversityShow Abstract
Bilal Farooq, Ryerson University
The recent advent of connected and automated vehicles (CAVs) is expected to transform the transportation system. CAV technologies are being developed rapidly and they are foreseen to penetrate the market soon. On the other hand, work zones (WZs) have become common areas on highway systems as a result of the increasing construction and maintenance activities. The near future will therefore bring the coexistence of CAVs and WZs which makes their interaction inevitable. WZs expose all vehicles to a sudden and complex geometric change in the roadway environment, something that may challenge many of CAV navigation capabilities. WZs however also impose a space contraction resulting in adverse traffic operational and safety impacts, something that legitimately calls for benefiting from the highly efficient CAV mobility and safety functions. CAVs should be able to reliably traverse WZ geometry and WZs should benefit from CAV intelligent functions. This paper explores the key concepts of deploying CAV systems at WZs with a focus on mobility, safety, and infrastructure considerations. The paper also provides a review on the recent literature and summarizes a research agenda. The paper aims to provide a bird’s eye view, but with necessary details that can benefit practitioners, planners, and transportation agencies.
The History of Rural Interstate Speed Limits in the United States
Thomas Cook, HDRShow Abstract
Michael Pawlovich, South Dakota State University
Reginald Souleyrette, Kentucky Transportation Cabinet
The impacts of speed limit increases on the Interstate Highway System (IHS) have been studied and researched many times over the course of the last 50 years in the United States. These research efforts began after the implementation of the National Maximum Speed Law (NMSL), which reduced all speed limits to a maximum of 55-mph. In the following years, this restriction was relaxed to 65-mph with the Surface Transportation and Uniform Relocation Assistance Act (STURAA) and ultimately was later repealed by the National Highway System Designation Act (NHSDA). Since the repeal, states have reacted in diverse ways with some relaxing rural interstate limits to historic high speeds and others maintaining limits of 60-mph or 65-mph. Despite trends of speed limit relaxation, future technological innovations such as vehicle connectivity and automation, vehicle energy source, and variable speed limits will pose many safety questions and potentially affect how these speed limits are set. In order to provide greater context, this paper seeks to present a proper summation of the legal and analytical aspects of rural interstate speed limit history in the United States and to consider what will affect these limits in the future.
Evaluation of the Effectiveness of Dynamic Speed Feed Back Signs in Work Zones on High-Speed Kansas Roadways
Samantha Anderson, Kansas State UniversityShow Abstract
Jack Cunningham, Kansas State University
Jia Liang, Kansas State University
Eric Fitzsimmons, Kansas State University
Work zones are essential to keeping our roadways preserved so they are safe and efficient. Work zones tend to increase safety risks due to the normal driving’s changing conditions whether short or long-term. In 2017, there were 799 fatalities in work zones; this showed a 3% increase from 2016 (FHWA, 2019). In order to reduce safety risks, reduced speed limits are used throughout work zones. However, different vehicle speeds across a work zone site can increase traffic congestion, delay, increase crashes if not properly signed using temporary traffic control and / or a reduction in vehicle speed. The objective of this study was to evaluate vehicle speed profiles in work zones and determine a dynamic speed feedback sign’s overall effectiveness. Three work zone sites in Kansas were evaluated in this study using pneumatic road tubes. Work zone 1 compared the accuracy of tracing vehicles using a computer program versus manual tracing. Work zones 2 and 3 included a dynamic speed feedback sign to notify drivers they were traveling above the posted work zone speed. Manual tracing of individual vehicles gave researchers more accurate results when evaluating speed. A statistical analysis found that work zones 2 and 3, had significant speed reductions. However, work zone 3 showed the most consistent reductions and put vehicle speeds closer to the posted speed limit. Additionally, passenger vehicles and tractor-trailer trucks proved most likely to exceed the posted speed limit. Overall, the dynamic speed feedback sign was found to be effective.
State-of-the-Art Methods in Estimating Freeway Work zones Capacity: A Literature Review
Ali Hassandokht Mashhadi, University of UtahShow Abstract
Mohammad Farhadmanesh, University of Utah
Abbas Rashidi, University of Utah
Nikola Markovic, University of Utah
Road reconstruction and the resulting work zones are considered as a major source of traffic congestion and delays on freeways. The roadway capacity is decreased due to a reduced number of traffic lanes, work zone speed limits, and narrower lanes. Accurate prediction of work zone capacity helps traffic engineers to have a better estimation of the traffic flow characteristics. To this end, multiple methodologies have been developed to quantify the impacts of work zones on traffic flow. This paper presents a critical review of the three types of approaches to estimating work zones capacities, including parametric, non-parametric, and simulation. Then the most commonly considered factors and their frequency are presented. It also performs a detailed review of the approaches and objectives. Lastly, it provides recommendations for future research.
A Methodology to Evaluate the Impact of Signage on Interstate Speeds using Vehicle Trajectory Data
Jenna Kirsch, Wayne State UniversityShow Abstract
Jonathan Waddell, Wayne State University
Stephen Remias (email@example.com), Wayne State University
Well operated transportation facilities require effective tools and performance metrics to evaluate the impact traffic control devices have on drivers. Managing traffic relies on providing useful information to drivers and understanding the impact messaging has on driver behavior. Transportation engineers often perform speed limit studies, install signage, immediately measure results, and declare victory. Active traffic management requires transportation engineers to dynamically provide messaging to drivers. Effective active traffic management requires engineers to understand the impact those messages are having on driver behavior. This study introduces a methodology using crowd sourced vehicle trajectory data to understand the influence of signage and elevation change on vehicle speeds. Four case studies are presented using a newly proposed speed profile graphic on I-75 near Chattanooga, Tennessee. The case studies investigate a speed limit increase, a speed limit decrease, a speed limit sign with no speed change, and dynamic message signs. The results of these case studies show that signage can impact driver speeds in counter-intuitive ways. Using crowd sourced trajectory data and aggregated speed profile graphics provides the opportunity for agencies and engineers to better understand the impact of signage on traffic. This proof of concept study provides a tool for future engineers to study effective signage placement and messaging techniques.
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