Repeatability and Reproducibility of Mobile Retroreflectivity Units for Measurement of Pavement Markings

Author(s):  
Bouzid Choubane ◽  
Joshua Sevearance ◽  
Hyung Suk Lee ◽  
Patrick Upshaw ◽  
James Fletcher

The Florida Department of Transportation has historically used a combination of handheld devices and visual surveys to evaluate the retroreflectivity of pavement markings. However, visual surveys have the inherent limitations of operator bias, while the use of a handheld device is slow and labor intensive and presents safety hazards. Many highway agencies have recognized that a mobile retroreflectivity unit (MRU) may be a safer and more efficient alternative to the handheld retroreflectometers. Because the measurement process relies on the operator-driven instrument, a level of uncertainty is always a concern in evaluating pavement markings with the MRU. This research was aimed at assessing the precision and bias of the MRU while using the handheld retroreflectometer as a reference device. Ten 1.0-mi-long field sites were selected to include various pavement surface types and pavement marking materials (paints and thermoplastics). The results indicated that, when compared with the handheld retroreflectometers, the MRU demonstrated no statistical differences or bias at a 95% confidence level for the retroreflectivity values ranging between 200 and 800 mcd/m2/lux. In addition, it was determined that the retroreflectivity values from two properly conducted tests using a single MRU on the same pavement marking should not differ by more than 7.8%, and when different MRUs were used on the same pavement marking, the retroreflectivity values should not differ by more than 13.3%. This paper presents a description of the testing program, the data collection effort, and the subsequent analyses and findings.

Author(s):  
Bouzid Choubane ◽  
Joshua Sevearance ◽  
Charles Holzschuher ◽  
James Fletcher ◽  
Chieh (Ross) Wang

The visibility of pavement markings is an important aspect of a safe transportation system as the markings convey vital roadway warnings and guidance information to the traveling public. Therefore, it is beneficial to maintain acceptable visibility levels of markings on pavements under all weather and lighting conditions. To ensure the intended in-service visibility level is adequately maintained, the reflectivity must be monitored and quantified accordingly. Historically, visibility or retroreflectivity of in-service pavement markings has been measured with handheld devices and visual inspections. However, visual surveys are considered subjective and the handheld measurements are tedious and potentially hazardous. Consequently, the Florida Department of Transportation (FDOT) has focused on the use of a non-contact technology capable of assessing pavement markings continuously at highway speeds with improved safety and efficiency. The use of mobile technology for measuring reflectivity has allowed FDOT to develop and, subsequently, implement a Pavement Marking Management System (PMMS) to improve the safety and nighttime visibility of its roadways. Implementation of such a system provides an efficient and less subjective methodology to identify conditions that are detrimental to roadway safety, and strategize mitigating solutions including the selection of appropriate materials and application techniques. The system will ultimately result in an effective use of state funds while ensuring the safety of the traveling public. This paper presents a description of the Florida Pavement Markings Management System and its subsequent implementation including FDOT’s effort to ensure the quality, consistency, repeatability, and accessibility of statewide pavement marking retroreflectivity data.


Author(s):  
William C. Taylor ◽  
Ghassan Abu-Lebdeh ◽  
Sachin Rai

Shoulder rumble strips and enhanced pavement markings were two key areas identified by AASHTO to reduce runoff-road collisions. The Michigan Department of Transportation is currently testing the effectiveness of placing shoulder rumble strips close to the edge of travel lanes and painting a line on the rumble strip to improve the retroreflective properties of the line. Two issues arise from placing the rumble strips closer to the edge line and moving the paint line onto the rumble strip: the potential increased noise when vehicles crossed over the rumble strips and damage to the pavement if vehicles moved closer to the construction joint between the travel lane and the shoulder. This study found that simply moving the paint line onto the rumble strips resulted in vehicles moving slightly closer to the edge of the travel lane. However, maintaining the current edge line and adding an additional paint line on the rumble strip resulted in vehicles moving away from the edge of the pavement and thus reduced noise and potential damage to the pavement.


2003 ◽  
Vol 1824 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Neville A. Parker ◽  
Massawe S. J. Meja

As an implementation strategy of the federal retroreflectivity standards requirement for pavement markings, the New Jersey Department of Transportation (DOT) evaluated its 3-year fixed-schedule restriping strategy, to determine if it is consistent with the actual service life of the pavement markings. The methodology and results of the study are presented. Two types of data were collected: measured retroreflectivity by using LaserLux and subjective ratings from a survey conducted with the participation of the New Jersey driving public along a 32-mi circuit. Multiple regression techniques were used to correlate the average scores reported by the study participants for each specific roadway section with the corresponding measured retroreflectivity. The results suggested that the threshold value of an acceptable versus unacceptable level of retroreflectivity appeared to be between 80 and 130 mcd/m2/lux for New Jersey drivers younger than 55 and between 120 and 165 mcd/m2/lux for drivers older than 55. These results are consistent with conclusions reached by other investigators in similar research, where results generally ranged between 70 and 170 mcd/m2/lux. Interim visibility indices were developed for each age group per pavement-marking type. New Jersey DOT used the indices to determine and prioritize needs and to quantify needed related resources, on the basis of the threshold between acceptable retroreflectivity and unacceptable retroreflectivity, when it developed its pavement-marking management system. This approach also allows for cost-benefit and life-cycle analysis for different pavementmarking materials.


Author(s):  
Scott Gabree ◽  
Stephanie Chase ◽  
Marco daSilva

The United States Department of Transportation’s (USDOT) John A. Volpe National Transportation Systems Center (Volpe Center), under the direction of the USDOT Federal Railroad Administration (FRA) Office of Research and Development (R&D), recently completed a study on the use of pavement markings to reduce instances of vehicles stopping on the tracks at grade crossings. Specifically, the study evaluated the effectiveness of pavement markings placed within the dynamic envelope, the region between and immediately adjacent to the tracks at a grade crossing, and new corresponding signage at the Commercial Boulevard grade crossing (ID# 628186E) in Ft. Lauderdale, Florida. The goal of this research study was to gain an understanding of the effect of dynamic envelope pavement markings and accompanying signage on driver’s not stopping while traversing the tracks. The addition of the dynamic envelope markings and signage is intended to make this area more pronounced, resulting in fewer motorists entering the dynamic envelope if they are unable to exit the other side. Researchers coded driver stopping behavior at this crossing before and after the surface treatments were installed. Vehicles were coded as having stopped in one of four zones: behind the stop line and gate arm (Zone 1), past the stop line but before the tracks (Zone 2), on the tracks (Zone 3), or immediately after the tracks (Zone 4). Stopping in Zone 3 is considered to be the most dangerous behavior that a driver could perform, while stopping in Zone 1 is the safest. The goal of the added markings and signage is to reduce the number of vehicles which come to a stop within the dynamic envelope, thus reducing the possibility that a vehicle is present on the tracks when a train approaches resulting in a collision. The addition of the dynamic envelope pavement markings and modified signage resulted in a statistically significant change in driver stopping behavior. Specifically, the pavement markings and signage reduced the proportion of vehicles that stopped in Zone 3, resulting in a 45% reduction in vehicles stopped in Zone 3 for eastbound vehicles and 14% for westbound vehicles. They also increased the proportion of vehicles stopping in Zone 1, which is the safest behavior a driver can perform (9% increase for eastbound and 6% increase for westbound). Additionally, fewer vehicles were found to stop in both Zone 2 and Zone 4, which are both moderately dangerous. Based on these results, the Florida Department of Transportation is exploring the use of this safety treatment at additional grade crossings with a high risk for unsafe vehicle stopping behavior.


Author(s):  
Madaniyo I. Mutabazi ◽  
Eugene R. Russell ◽  
Robert W. Stokes

Traditionally, highway improvement project evaluation is done without incorporating highway users’ views. The Kansas Department of Transportation (KDOT) wants drivers to be satisfied and have “good feelings” about its passing lanes program. KDOT needs input to decide whether passing lanes are efficient, safe, and acceptable to the public. Drivers’ views were solicited via a questionnaire survey which was part of a comprehensive study on passing lanes in Kansas. Generally, drivers support the passing lane program and suggest construction of more passing lanes. Drivers think that passing lanes are more beneficial for improving safety than for saving time. They are equally divided on the length of passing lanes between “too short” and “just right,” although the provided lengths are within the recommended optimum lengths found in the literature. The “too short” responses could be due to existing passing lane spacings, preference of four-lane highways over two-lane highways, and difference in local conditions from those used to determine lengths. Drivers cited fellow drivers’ failure to follow signs and markings properly, and failure to use the lanes properly; this seems to indicate that improvements in signing and pavement markings should be considered. A smaller proportion of drivers, satisfied with a lower frequency of local travel on a route closer to the state’s borders (i.e., more unfamiliar drivers), suggests the importance of standardizing highway operating and design practices throughout the country.


Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1737
Author(s):  
Ane Dalsnes Storsæter ◽  
Kelly Pitera ◽  
Edward McCormack

Pavement markings are used to convey positioning information to both humans and automated driving systems. As automated driving is increasingly being adopted to support safety, it is important to understand how successfully sensor systems can interpret these markings. In this effort, an in-vehicle lane departure warning system was compared to data collected simultaneously from an externally mounted mobile retroreflectometer. The test, performed over 200 km of driving on three different routes in variable lighting conditions and road classes found that, depending on conditions, the retroreflectometer could predict whether the car’s lane departure systems would detect markings in 92% to 98% of cases. The test demonstrated that automated driving systems can be used to monitor the state of pavement markings and can provide input on how to design and maintain road infrastructure to support automated driving features. Since data about the condition of lane marking from multiple lane departure warning systems (crowd-sourced data) can provide input into the pavement marking management systems operated by many road owners, these findings also indicate that these automated driving sensors have an important role in enhancing the maintenance of pavement markings.


Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 15
Author(s):  
Filippo Aleotti ◽  
Giulio Zaccaroni ◽  
Luca Bartolomei ◽  
Matteo Poggi ◽  
Fabio Tosi ◽  
...  

Depth perception is paramount for tackling real-world problems, ranging from autonomous driving to consumer applications. For the latter, depth estimation from a single image would represent the most versatile solution since a standard camera is available on almost any handheld device. Nonetheless, two main issues limit the practical deployment of monocular depth estimation methods on such devices: (i) the low reliability when deployed in the wild and (ii) the resources needed to achieve real-time performance, often not compatible with low-power embedded systems. Therefore, in this paper, we deeply investigate all these issues, showing how they are both addressable by adopting appropriate network design and training strategies. Moreover, we also outline how to map the resulting networks on handheld devices to achieve real-time performance. Our thorough evaluation highlights the ability of such fast networks to generalize well to new environments, a crucial feature required to tackle the extremely varied contexts faced in real applications. Indeed, to further support this evidence, we report experimental results concerning real-time, depth-aware augmented reality and image blurring with smartphones in the wild.


2021 ◽  
Vol 6 (2) ◽  
pp. 18
Author(s):  
Alireza Sassani ◽  
Omar Smadi ◽  
Neal Hawkins

Pavement markings are essential elements of transportation infrastructure with critical impacts on safety and mobility. They provide road users with the necessary information to adjust driving behavior or make calculated decisions about commuting. The visibility of pavement markings for drivers can be the boundary between a safe trip and a disastrous accident. Consequently, transportation agencies at the local or national levels allocate sizeable budgets to upkeep the pavement markings under their jurisdiction. Infrastructure asset management systems (IAMS) are often biased toward high-capital-cost assets such as pavements and bridges, not providing structured asset management (AM) plans for low-cost assets such as pavement markings. However, recent advances in transportation asset management (TAM) have promoted an integrated approach involving the pavement marking management system (PMMS). A PMMS brings all data items and processes under a comprehensive AM plan and enables managing pavement markings more efficiently. Pavement marking operations depend on location, conditions, and AM policies, highly diversifying the pavement marking management practices among agencies and making it difficult to create a holistic image of the system. Most of the available resources for pavement marking management focus on practices instead of strategies. Therefore, there is a lack of comprehensive guidelines and model frameworks for developing PMMS. This study utilizes the existing body of knowledge to build a guideline for developing and implementing PMMS. First, by adapting the core AM concepts to pavement marking management, a model framework for PMMS is created, and the building blocks and elements of the framework are introduced. Then, the caveats and practical points in PMMS implementation are discussed based on the US transportation agencies’ experiences and the relevant literature. This guideline is aspired to facilitate PMMS development for the agencies and pave the way for future pavement marking management tools and databases.


2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Zhi Huang ◽  
Xinsheng Zhang ◽  
Ming Zhou ◽  
Xiaoding Xu ◽  
Xianzheng Zhang ◽  
...  

Increasing functionality demands more heat dissipation from the skin of handheld devices. The maximum amount of heat that can be dissipated passively, prescribed by the natural convection and blackbody radiation theories, is becoming the bottleneck. In this letter, we propose a novel bio-inspirited technique that may overcome this passive cooling limit. It is made possible by using a biomimetic skin capable of perspiration on demand. The key component of the biomimetic skin is a thin layer of temperature sensitive hydro gel (TSHG). The TSHG layer can sweat the skin with moisture when the skin temperature is higher than the TSHG’s lower critical solution temperature (LCST), and thus boost the heat dissipation rate through evaporation. The TSHG layer can absorb moisture at low temperature to replenish. With this novel passive cooling technology, a handheld device can have nearly four times more power beyond the traditional passive cooling limit, and may be powerful enough to run a desktop operation system like a full functional personal computer.


Author(s):  
Timothy P. Barrette ◽  
Adam M. Pike

Raised retroreflective pavement markers (RRPMs) are commonly used to provide nighttime delineation of roadways. Although RRPMs are visible during dry conditions, they provide their greatest benefit during wet-night conditions, when typical pavement markings become flooded and lose their retroreflectivite properties. Naturally, the retroreflectivity of RRPMs degrades over time as a result of traffic, ultraviolet light, precipitation, and roadway maintenance activities. Subsequently, it is necessary to examine the relationship between driver performance and the condition of the RRPMs. To assess visibility relative to RRPM condition, study participants rode in the passenger seat of a vehicle operated by a member of the research team, traveling at approximately 15 mph, for two laps around a closed course. Throughout each lap of the course, nine treatments consisting of RRPMs or preformed pavement marking tape of various retroreflectivity levels diverged from a center line to either the right or left. Participants indicated when they could tell which direction the treatment diverged, which was recorded using a GPS unit. A generalized linear model was estimated on a dataset constructed by pairing the observed distances from various treatments with demographic information about each participant. The analysis indicates the distance at which a particular treatment would be visible, which can then be converted to preview time to assess treatment adequacy for a variety of speeds. The RRPM treatments generally provided adequate preview time for older drivers based on the extant literature; however, the preformed pavement marking tape was less adequate at higher speeds and under overhead lighting.


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