Using Crowdsourced Vehicle Braking Data to Identify Roadway Hazards

The Federal Highway Administration (FHWA) reported between 2016 and 2017, fatal crashes in work zones increased by 3%, while fatal crashes outside of work zones decreased by 1.5%. The FHWA also reported that work zones account for approximately 10% of the nation’s overall congestion and 24% of unexpected interstate delays. This paper reports on a study of 23 construction work zones that covered approximately 150 centerline miles of Indiana interstate roadway in the summer of 2019. Approximately 50% of all interstate crashes for the period of May to September 2019 occurred within or in an approach upstream or downstream of one of these work zones. Commercially available vehicle hard-braking event data is used for the study and geofenced to the work zone approaches and limits. This research examined 196,215 hard-braking events over a 2-month period in the summer of 2019 and 3132 crashes over the same 2-month period in 2018 and 2019 for the 23 interstate work zones. The study found there were approximately 1 crash/mile for every 147 hard-braking events in and around a construction site. The R2 was approximately 0.85. The paper concludes by recommending that hard-braking event data be used by agencies to quickly identify emerging work zone locations that show relatively large number of hard-braking events for further evaluation.

Potentially inappropriate medications (PIMs) identified by the American Geriatrics Society should generally be avoided by older adults because of ineffectiveness or excess risk of adverse effects. Few studies have examined the effects of PIMs on driving safety measured by prospectively and objectively collected driving data. Data for this study came from the Longitudinal Research on Aging Drivers study, a multisite naturalistic driving study of older adults. Multivariable negative binominal modeling was used to estimate incidence rate ratios and 95% confidence intervals of hard braking events (proxies for unsafe driving behavior defined as events with a deceleration rate ≥0.4 g) associated with PIM use among older drivers. The study sample consisted of 2932 drivers aged 65–79 years at baseline, including 542 (18.5%) who used at least one PIM. These drivers were followed through an in-vehicle recording device for up to 44 months. The overall incidence of hard braking events was 1.16 per 1000 miles. Use of PIMs was associated with a 10% increased risk of hard braking events. Compared to drivers who were not using PIMs, the risk of hard braking events increased 6% for those using one PIM, and 24% for those using two or more PIMs. Use of PIMs by older adult drivers is associated in a dose-response fashion with elevated risks of hard braking events. Reducing PIM use in older adults might help improve driving safety as well as health outcomes.

Identifying risk factors for road traffic injuries can be considered one of the main priorities of transportation agencies. More than 12,000 fatal work zone crashes were reported between 2000 and 2013. Despite recent efforts to improve work zone safety, the frequency and severity of work zone crashes are still a big concern for transportation agencies. Although many studies have been conducted on different work zone safety-related issues, there is a lack of studies that investigate the effect of adverse weather conditions on work zone crash severity. This paper utilizes probit–classification tree, a relatively recent and promising combination of machine learning technique and conventional parametric model, to identify factors affecting work zone crash severity in adverse weather conditions using 8 years of work zone weather-related crashes (2006–2013) in Washington State. The key strength of this technique lies in its capability to alleviate the shortcomings of both parametric and nonparametric models. The results showed that both presence of traffic control device and lighting conditions are significant interacting variables in the developed complementary crash severity model for work zone weather-related crashes. Therefore, transportation agencies and contractors need to invest more in lighting equipment and better traffic control strategies at work zones, specifically during adverse weather conditions.

<div class="htmlview paragraph">This paper discusses one method for reducing heavy-duty truck rollover accidents, the Freightliner/MeritorWABCO Roll Advisor and Control (RA&C) System. It describes the operation of this system and the unique way in which RA&C trains drivers to avoid high-risk rollover and braking conditions. In addition, the rationale for this approach is discussed in terms of Behavioral Based Safety (BBS), and the means employed to communicate with drivers is described.</div> <div class="htmlview paragraph">A technical description of the RA&C system is presented including a discussion of the challenges of designing and developing this product to be a cost-effective system readily implemented in today's commercial vehicles. Resolution of these challenges leads to the choice of the ABS platform to house and operate the necessary electronics and software along with the Freightliner Driver Message Center for displaying driver information. To maximize reliability and keep installation as simple as possible, all external sensors were eliminated and the existing vehicle data busses were employed to transfer all required information.</div> <div class="htmlview paragraph">As a BBS system, RA&C presents timely performance feedback to help the driver to reduce the incidence of rollover risk and hard braking events. The design of the interface employed the Freightliner Driver Message Center platform and was guided by the implementation of human factors principles and driver testing. Several methods are used to communicate the degree of rollover risk. Driving advisories are provided as guidance for avoiding future rollover risk situations. In addition, a method that allows drivers to monitor driving performance through access to cumulative rollover risk and hard braking event message counts is discussed.</div>

Inferring heterogeneous treatment effects of work zones on crashes

Transportation agencies across the U.S. are expending a great deal of effort to improve highway work zone safety. Among those efforts is a special fund for work zone enforcement established by the Indiana Department of Transportation (INDOT). The allocation of enforcement funding was based on expert knowledge and weights and scores applied to work zone characteristics considered relevant to traffic safety. The objective of the reported project was to develop a rational and defendable tool for programming police enforcement that maximizes the safety benefits of police enforcement in INDOT work zones.\nTo understand what affects work zone safety, the research team carried out an extensive literature review, designed field experiments to evaluate the effect of selected enforcement strategies on drivers’ behavior in work zones, and developed speed models incorporating the effect of police enforcement. The estimated speeds were used to derive CMFs that express the effect of the police enforcement strategy on work zone safety. Finally, the research team combined all of the developed components in a method of predicting the costs and the safety benefits in works zones under various enforcement strategies. This last method was included in the optimization tool for programming police enforcement in a group of planned work zones.\nThe described project developed an optimization tool implemented in a Microsoft Excel spreadsheet with the OpenSolver add-in. The tool is flexible, straightforward, and easy to use. The user should be able to quickly become familiar with the required input, results, and obtained solution.

Work zones pose mobility issues to the traveling public and safety challenges to travelers and road maintenance workers. These safety and mobility issues may be exacerbated by the presence of heavy vehicles. Connected and automated vehicle (CAV) technologies have been identified as a potential solution for these issues. This paper investigates the operational impacts of connected and automated heavy vehicles (CAHV) on freeway work zone operations on interstate highways. A microsimulation model, calibrated to empirical work zone field data, was used to study the operational impacts of CAHV platoons under various work zone and traffic conditions. It was found that, as the CAHV market penetration rate increases, the average work zone delay and queue length decreases. In addition, as the demand and heavy vehicle percentage increases, so do the benefits of using CAHV technology. For example, it was found that, when all heavy vehicles are classified as CAHV, the average flow rate is approximately 67% higher, and the maximum queue size and average delay decrease by approximately 97%. The methodology used in this paper will help transportation agencies as they design work zones to accommodate heavy vehicles equipped with CAV technologies.

<b>Objective:</b> Work zone safety is one of the top priorities for transportation agencies. In recent years, a considerable volume of research has sought to determine work zone crash characteristics and causal factors. Unlike other non–work zone–related safety studies (on both crash frequency and severity), there has not yet been a comprehensive review and assessment of methodological approaches for work zone safety. To address this deficit, this article aims to provide a comprehensive review of the existing extensive research efforts focused on work zone crash-related analysis and modeling, in the hopes of providing researchers and practitioners with a complete overview.<b>Methods:</b> Relevant literature published in the last 5 decades was retrieved from the National Work Zone Crash Information Clearinghouse and the Transport Research International Documentation database and other public digital libraries and search engines. Both peer-reviewed publications and research reports were obtained. Each study was carefully reviewed, and those that focused on either work zone crash data analysis or work zone safety modeling were identified. The most relevant studies are specifically examined and discussed in the article.<b>Results:</b> The identified studies were carefully synthesized to understand the state of knowledge on work zone safety. Agreement and inconsistency regarding the characteristics of the work zone crashes discussed in the descriptive studies were summarized. Progress and issues about the current practices on work zone crash frequency and severity modeling are also explored and discussed. The challenges facing work zone safety research are then presented.<b>Conclusions:</b> The synthesis of the literature suggests that the presence of a work zone is likely to increase the crash rate. Crashes are not uniformly distributed within work zones and rear-end crashes are the most prevalent type of crashes in work zones. There was no across-the-board agreement among numerous papers reviewed on the relationship between work zone crashes and other factors such as time, weather, victim severity, traffic control devices, and facility types. Moreover, both work zone crash frequency and severity models still rely on relatively simple modeling techniques and approaches. In addition, work zone data limitations have caused a number of challenges in analyzing and modeling work zone safety. Additional efforts on data collection, developing a systematic data analysis framework, and using more advanced modeling approaches are suggested as future research tasks.

During drive off maneuvers from stand still with high torque unpleasant longitudinal oscillations of the vehicle occur, commonly referred to as the power hop phenomenon. This effect especially arises in vehicles with manual transmission in a maneuver with abrupt release of the clutch, also known as snap start. Traction control on the engine control unit provides a cheap and easy way to reduce power hop and thus to improve the comfort for the passengers. In this paper two methods for estimation of tire road friction coefficient during snap start are presented with regard to road condition dependent parametrization of a Sliding Mode traction control. Since the road conditions can change in every maneuver, a fast but also accurate estimation algorithm is necessary. The first method is based on a vehicle model and uses an Extended Kalman Filter to estimate the current maximum friction coefficient. The second method uses only wheel speed measurements to deduce information about the road condition. These methods can be used to adapt the parameters of the control algorithm to different road surfaces and thus improve the performance. Experimental results on different road surfaces are presented.

Typical traffic control and operations at work zones are not effective in mitigating the work zone bottleneck, as the common early merge behavior limits utilizing the available capacity in the closed lane. Recently, using late merge strategy is encouraged to fully utilize the closed lane, therefore increasing efficiency of the work zone. In practice, the late merge strategy does not work effectively due to the lack of compliance by drivers. This paper is aimed at exploring two work zone late merge strategies with and without enabling connected vehicles (CV) technology. This first strategy is the late merge without CV enabled. The second strategy incorporates CV-enabled cooperative merge to enhance the work zone efficiency through communications between vehicles in the open and closed lanes. The CV-enabled strategy employs a rule based decentralized control algorithm. The paper has implemented both late merge strategies in microsimulation and evaluated the operational performances. Three major performance measures, which are throughput, delay and queue length, are used in the evaluation. The results indicate that the operational performance of the CV-enabled cooperative late merge is superior to the late merge strategy without CV in most cases, especially when traffic demand is moderate, while both late merge strategies outperform the traditional early merge strategy. Moreover, effects of the control variables including the traffic demand, heavy vehicle percentage, lane distribution percentage, late merge length, reduction of gap acceptance factor, and compliance rate, have been analyzed. Ultimately, sensitivity analysis has been performed to investigate the trend of effects from the significant variables control.

The sustained deterioration of the freeway infrastructure of a nation has resulted in an increase in the number, duration, and scope of maintenance projects. In order to enhance the mobility and safety of freeway segments plagued by work zone activities, transportation agencies and professionals have been exploring the potential benefits of efficient and economical maintenance scheduling. This thesis proposes systematic methodology for the optimization of work zone scheduling based on analytical and simulation models to estimate total project cost. Multi-regression models were developed using microsimulation and embedded them into the costs models and costs were predicted. Solver optimizer was used to find the optimal start and end times, productivity indices, and corresponding sub-sectional lengths of project by minimizing the total project cost. Case studies were conducted to assess the performance of the proposed methodology. Lastly, conclusions were made to support transportation agencies in the development of work zone management plans.

Mitigation strategies for work zone congestion are used by transportation agencies to manage or reduce congestion through a work zone as part of the project's transportation management plan. The objective of this research is to assist agencies’ strategy selection by identifying strategies used by state transportation agencies (STAs) nationwide and their experiences. An online survey was developed to identify current, past, and future strategy implementation for projects similar to four developed scenarios: rural reconstruction, rural resurfacing, urban reconstruction, and urban resurfacing projects. The survey received 42 responses from individuals representing 28 states (responses were received from multiple districts or regions from a few states). It was found that agencies used several strategies to address different aspects of mobility and safety. Strategy selection varied between facility location and work activity. STAs also provided strategies that failed to meet expectations and identified strategies their agency plans to implement in the future. Based on the survey results and gaps in current literature, recommendations for strategy selection and future research are provided.

This paper presents a novel piezoactuator-based valve for vehicle ABS. The piezoactuator located in one side of a rigid beam makes a displacement required to control the pressure at a flapper-nozzle of the pneumatic valve. In order to obtain the wide control range of the pressure, a pressure modulator comprised of dual-type cylinder and piston is proposed. The governing equation of the piezovalve system which consists of the proposed piezoactuator-based valve and the pressure modulator is obtained. The longitudinal vehicle dynamics and the wheel slip condition are then formulated. In order to evaluate the performance of the proposed piezovalve system from the viewpoint of the vehicle ABS, a sliding mode controller is designed for wheel slip control. The tracking control performances for the desired wheel slip rate are evaluated and the braking performances in terms of braking distance are then presented on different road conditions (dry asphalt, wet asphalt, and wet jennite). It is clearly shown that the desired wheel slip rate is well achieved and the braking distance and braking time can be significantly reduced by using the proposed piezovalve system associated with the slip rate controller.

Controller design for vehicle stability enhancement

&lt;div&gt;In order to improve the safety and dynamic performance of electric vehicles equipped with four in-wheel electric motors, and prevent the wheels from locking or slipping when braking or accelerating, a new longitudinal control strategy which combines ASR traction and ABS braking control is proposed using an observation algorithm of effective radius for four wheel of electric vehicle. Using the electric motor torques as the unique actuator signal sources, this combined ASR/ABS can act as acceleration slip regulation (ASR) by preventing the wheels from slipping during acceleration and as an antilock braking system (ABS) by preventing the wheels from getting locked during braking. A variation of effective radius of the wheel’s tire can have an incidence on the longitudinal and lateral control. Moreover, the wheel effective radius observer based on high order sliding mode approach using the information of the electric motor torques and the angular velocities is used in the combined ASR/ABS systems. First, adjusting the motor torque and based on Fuzzy logic control, the acceleration slip regulation (ASR) is designed to maintain the wheel slip in the optimal range using the angular acceleration and slip rate. Second, for limiting the wheel slip by adjusting the motor torque the sliding mode control is used. Several Matlab/Simulink simulation tests will be carried out to validate the effectiveness of the proposed controller.&lt;/div&gt;