Roadway Conditions Research Articles

Impact of Inclement Weather on Left-Turn Gap Acceptance Behavior of Drivers

This paper describes an empirical study conducted to quantify the impact of a number of variables on left-turn gap acceptance behavior of drivers at signalized intersections. The variables include the gap duration, the travel time needed to cross the intersection, and the corresponding weather condition. The gap acceptance data set used in the study included 11,114 observations (1,176 accepted gaps and 9,938 rejected gaps) for a permitted left-turn maneuver at a signalized intersection; the data were gathered over 6 months. The data set was divided into six weather categories for different combinations of precipitation and roadway surface conditions. Logistic regression models were calibrated to the data and compared to identify the best model for capturing gap acceptance behavior of drivers. The models reveal that drivers are more conservative during snow than rain. Drivers require larger gaps for wet surface conditions than for snowy and icy surface conditions, and drivers require the smallest gaps for dry roadway conditions. In addition, the models show that drivers require larger gaps as the distance required to traverse the offered gap increases. The study also shows how inclement weather and the number of opposing lanes affect permitted left-turn saturation flow rates. It is anticipated that these findings will be used to develop weather-specific traffic signal timings that account for changes in traffic stream saturation flow rates and also used for intelligent assistance systems for drivers.

Coupling study between Rheology And Electromagnetic Emission of Coal or Rock Dynamic Catastrophe

This paper provides a theory of coal and rock rheological electromagnetic radiation coupling based on the generalized original model by using theoretical analysis, numerical simulation, field test and analysis of the coal rock material damage characteristics and strength statistics. On this basis, the software FLAC was used to simulate the roadway creep strain condition of # 2218 of Chengzhuang Coal Mine, and a research of electromagnetic radiation test on the tunnel was conducted. The practical testing results agree well with the analysis of theory. The results make contributions to the research on the usage of electromagnetic radiation and other disasters.

Detection and Correction of Inductive Loop Detector Sensitivity Errors by Using Gaussian Mixture Models

Inductive loop detectors (ILDs) form the backbone of many traffic detection networks by providing vehicle detection for freeway and arterial monitoring as well as signal control. Unfortunately, ILD technology generally has limited the available sensitivity settings. Changing roadway conditions and aging equipment can cause ILD settings that had been correct to become under- or oversensitive. ILDs with incorrect sensitivities may result in severe errors in occupancy and volume measurements. Therefore, sensitivity error identification and correction are important for quality data collection from ILDs. In this study, the Gaussian mixture model (GMM) is used to identify ILDs with sensitivity problems. If the sensitivity problem is correctible at the software level, a correction factor is then calculated for the occupancy measurements of the ILD. The correction methodology developed in this study was found effective in correcting occupancy errors caused by the ILD sensitivity problems. Single-loop speed calculation with the corrected occupancy increases the accuracy by 12%. Since this GMM-based approach does not require hardware changes, it is cost-effective and has great potential for easy improvement of archived loop data quality.

Empirical Study of Impact of Icy Roadway Surface Condition on Driver Car-Following Behavior

Research was done to quantify the impact of icy roadway conditions on driver car-following behavior. The data used in the study were gathered by a group of researchers at Japan's Hokkaido University in a controlled environment under dry and icy roadway conditions. The data were used to calibrate the Van Aerde steady-state car-following model, along with vehicle acceleration and deceleration constraints. The impact of icy roadway conditions on five driver-specific car-following parameters [driver perception–reaction time (PRT), free-flow or desired speed, speed-at-capacity, capacity, and jam density] was conducted with one-way analysis of variance and Kruskal–Wallis tests. The results demonstrate that icy roadway conditions produce statistically significant differences at a 5% significance level. Specifically, icy roadway conditions reduce the mean free-flow speed, speed at capacity, and capacity by 28%, 13%, and 46%, respectively, compared with driving on dry roadways. The mean PRT for icy conditions is found to take 13% longer than driving under dry conditions. The longer PRTs can be attributed to drivers driving at lower speeds and larger spacing on icy surfaces compared with dry conditions.

Relationship between soil erosion, slope, parent material, and distance to road (Case study: Latian Watershed, Iran)

Soil erosion is the dominating factor of damaging roads in Iran. Roads are a critical component of civilization. Developing and maintaining the economic activity that is vital for the quality of modern life would be difficult without roads. Accelerated erosion and increased sediment yields resulting from changes in land use are critical environmental problems, and one of the important changes is road construction. Construction and condition of roadways are associated with direct and indirect impacts on soil erosion. This paper presents the relationship between soil erosion and some characteristics such as distance to roadway, slope, and parent material in Latian Watershed, Tehran Province, Iran. Soil erosion map was interpreted using aerial photos and GIS technology. Buffer zones, subdivided into 12 strips, each 0.2 km wide, which were located alongside roadway. The distribution patterns of various types of erosion were also identified by GIS by overlaying road buffer strips and soil erosion map. The results show that soil erosion landform such as land slide, badland, bank erosion, channel erosion, etc. found in buffer zones along both sides of roads.

Safety Evaluation of Signalized Highway Intersections Based on the Concept of Level of Safety Service

Crash analysis or conflict analysis procedures have been used for intersection safety evaluation. Both approaches need significant data from crash databases or traffic conflict observations. It might be difficult and time-consuming to obtain these data. Actually, crashes happen with certain random characteristics, and conflict analysis could involve reviewer's subjective judgments. It is useful to develop alternative ways for intersection safety evaluation. These alternative ways could be based only on existing traffic control, geometric, and roadway conditions. A feasible approach belongs to such alternatives for safety evaluation of intersections is based on the concept of safety service that an intersection can provide to traveling public, or called level of safety service. This article presents partial results from a research aiming to developing safety design procedures for highway intersections. In the article, the concept of level of safety service of signalized intersections is introduced, and corresponding models are presented. Conceptually, models under ideal conditions are based only on intersection conflict points between motorized vehicles, between motorized vehicles and nonmotorized vehicles, and between motorized vehicles and pedestrians. Variables related to traffic control, geometrical, and roadway conditions under prevailing conditions are used to adjust models under ideal conditions to obtain level of safety service under prevailing conditions.

Microsimulation Study of Effect of Volume and Road Width on PCU of Vehicles under Heterogeneous Traffic

The traffic volume and roadway capacity are the important basic inputs required for planning, analysis, and operation of roadway systems. Expressing traffic volume as number of vehicles passing a given section of road or traffic lane per unit time will be inappropriate when several types of vehicles with widely varying static and dynamic characteristics are comprised in the traffic. The problem of measuring volume of such heterogeneous traffic has been addressed by converting different types of vehicles into equivalent passenger cars and expressing the volume in terms of passenger car unit (PCU) per hour. The vehicles of highly heterogeneous traffic such as the one prevailing on Indian roads may occupy any convenient lateral position on the road, based on the availability of space, without any lane discipline. This study is concerned with the estimation of PCU values of vehicles in such traffic conditions, using microscopic simulation. The PCU values obtained for different types of vehicles, for a wide range of traffic volume and roadway conditions, indicate that the PCU value of a vehicle significantly changes with change in traffic volume and width of roadway.

Effect of Gradient and Its Length on Performance of Vehicles under Heterogeneous Traffic Conditions

Study of the basic traffic-flow characteristics and clear understanding of vehicular interaction are the prerequisites for highway capacity and level of service analyses and to formulate effective traffic regulation and control measures. Computer simulation has emerged as an effective technique for modeling traffic flow and to study the flow characteristics over a wide range of roadway and traffic conditions due to its capability to account for the randomness related to traffic. This paper is concerned with application of a simulation model of heterogeneous traffic flow, named HETEROSIM, to quantify the vehicular interaction, in terms of passenger car unit (PCU), for the different categories of vehicles, by considering the traffic flow of representative composition, on up-grades of different magnitudes for intercity roads in India. The PCU estimates, determined through microscopic simulation, for the different types of vehicles in heterogeneous traffic, for a wide range of grades and traffic volumes, indicate that the PCU value of a vehicle significantly changes with change in traffic volume and magnitude of grade and its length.

A real-time versatile roadway path extraction and tracking on an FPGA platform

This paper presents an algorithm for roadway path extraction and tracking and its implementation in a Field Programmable Gate Array (FPGA) device. The implementation is particularly suitable for use as a core component of a Lane Departure Warning (LDW) system, which requires high-performance digital image processing as well as low-cost semiconductor devices, appropriate for the high volume production of the automotive market. The FPGA technology proved to be a proper platform to meet these two contrasting requirements. The proposed algorithm is specifically designed to be completely embedded in FPGA hardware to process wide VGA resolution video sequences at 30 frames per second. The main contributions of this work lie in (i) the proper selection, customization and integration of the main functions for road extraction and tracking to cope with the addressed application, and (ii) the subsequent FPGA hardware implementation as a modular architecture of specialized blocks. Experiments on real road scenario video sequences running on the FPGA device illustrate the good performance of the proposed system prototype and its ability to adapt to varying common roadway conditions, without the need for a per-installation calibration procedure.

Methodology for Determining Laboratory and In Situ Hydraulic Conductivity of Asphalt Permeable Friction Course

The permeable friction course (PFC) is a layer of porous asphalt pavement overlain on conventional impervious hot-mix asphalt or portland cement concrete. The drainage properties of PFC are typically considered to be governed primarily by two hydraulic properties: hydraulic conductivity and porosity. Both of these hydraulic properties change over the life cycle of the PFC layer due to clogging of the pore space by sediment. Therefore, determination of the hydraulic conductivity and porosity of PFC can be problematic. Laboratory and particularly field tests are necessary for accurately determining the hydraulic conductivity of the PFC layer. Taking multiple measurements over the life of the pavement shows how these hydraulic characteristics change with time and the varying roadway conditions at which they are evaluated. Constant head laboratory testing has shown that PFC experiences a nonlinear flow relationship as described by the Forchheimer equation. In addition to the laboratory analysis of the hydraulic characteristics, a falling head field test is recommended to determine the in situ hydraulic conductivity. This incorporates the modeling techniques used in the laboratory testing and applies them to the falling head conditions used in the field. The result is a nondestructive test procedure for determining the in situ hydraulic conductivity which is necessary for estimating the extent to which the benefits associated with the drainage characteristics of the PFC layer will persist.

Theoretical Framework for Modeling Pedestrians’ Crossing Behavior along a Trip

Explaining pedestrians' crossing behavior along entire trips may contribute toward more efficient and targeted planning of pedestrian facilities in urban areas and more accurate consideration of pedestrian safety. Although existing research on pedestrians' crossing behavior is extensive, most related studies examine pedestrians' crossing decisions at local level and focus on a particular set of determinants (roadway environment, traffic conditions, or human factors). On the contrary, crossing behavior along entire trips is seldom explored. This paper presents a theoretical framework for modeling pedestrians' crossing behavior along a trip, addressing a large part of the difficulties involved in collecting the necessary data and setting up a modeling framework. First, a topological approach of pedestrian trip characteristics and crossing decisions is proposed, allowing consideration of distinct patterns of crossing behavior along a trip. Moreover, specific techniques from the family of discrete choice models are proposed for determining the number and location of pedestrians' crossings, accounting for the hierarchical and dynamic nature of pedestrians' decisions along a trip. Finally, a field survey method is presented, allowing collection of detailed information about pedestrians' crossing decisions along urban trips, including data on roadway, traffic, and individual characteristics, as well as the interactions between pedestrians and motorists. Preliminary results from a pilot implementation of the proposed framework are promising, and a full-scale application for testing and validation is in progress.

Detection of Roadway Sign Condition Changes using Multi-Scale Sign Image Matching (M-SIM)

Roadway signs are important for safety, and transportation agencies need to identify sign condition changes to perform timely maintenance, including replacement. Currently, sign condition changes are inspected manually in the field, which is time consuming, costly, and sometimes dangerous. This paper first proposes a novel algorithm to detect 3 condition changes: missing, tilted and blocked signs, using GPS data and video log images. The algorithm consists of 3 steps: 1) Multi-scale Sign Image Matching (M-SIM), 2) image feature analysis, and 3) sign condition change detection and classification. The algorithm was tested using images with simulated sign condition changes and actual video images taken in Fiscal Year 2003 and 2005 by the Louisiana Department of Transportation and Development. The tests demonstrate that the algorithm is effective to detect the 3 types of sign condition changes. Out of 34,000 actual video log images, the algorithm detected and classified 100% of the missing signs, 72.7% of the tilted signs, and 66.7% of the blocked signs, for an overall 74.3% detection rate. These results show that the algorithm is useful for developing an intelligent roadway sign condition change detection system.

Public Internet‐connected cameras used as a cross‐continental ground‐based plant phenology monitoring system

AbstractPlant phenology is highly sensitive to changes in environmental conditions and can vary widely across landscapes. Current observation methods are either manual for small‐scale, high precision measurements or by satellite remote sensing for large‐scale, low spatial resolution measurement. The development of inexpensive approaches is necessary to advance large scale, high precision phenology monitoring. The use of publicly available, Internet‐connected cameras, often associated with airports, national parks, and roadway conditions, for detecting and monitoring plant phenology at a continental scale can augment existing ground and satellite‐based methodologies. We collected twice‐daily images from over 1100 georeferenced public cameras across North America from February 2008 to 2009. Using a test subset of these cameras, we compared modeled spring ‘green‐up’ with that from co‐occurring remote sensing products. Although varying image exposure and color correction introduced noise to camera measurements, we were able to correlate spring green‐up across North America with visual validation from images and detect a latitudinal trend. Public cameras had an equivalent or higher ability to detect spring compared with satellite‐based data for corresponding locations, with fewer numbers of poor quality days, shorter continuous bad data days, and significantly lower errors of spring estimates. Manual image segmentation into deciduous, evergreen, and understory vegetation allowed detection of spring and fall onset for multiple vegetation types. Additional advantages of a public camera‐based monitoring system include frequent image capture (subdaily) and the potential to detect quantitative responses to environmental changes in organisms, species, and communities. Public cameras represent a relatively untapped and freely available resource for supporting large‐scale ecological and environmental monitoring.

Improving the Safety of Mobile Lane Closures

Mobile lane closures, which are increasingly used, are a potentially hazardous traffic control procedure for highway maintenance and operations activities. To improve the safety of workers and motorists, Applied Research Associates, Inc., studied driver behavior around full-scale field tests of mobile lane closures. Tests were conducted over a range of traffic, roadway, and driver conditions, and effects of various traffic control components (including truck number, spacing, and configuration; sign messages; and police presence) were evaluated. This report summarizes Phase I results and important findings regarding the behavior of motorists around mobile lane closures. Phase II research is ongoing and will recommend revisions to existing traffic control standards.

Assessment of Data Quality for Evaluations of Manual Pavement Distress

Assessment of the conditions of current assets is a task of major relevance in a transportation agency asset management program. It not only provides information on the current condition of the asset but also helps the agency make decisions on future maintenance and rehabilitation activities. Although low-volume roadways represent a large proportion of the total road network in the United States, little research on the management of these assets has been done. Two major data collection techniques are used for roadway condition assessment: manual and automated. Although automated techniques have been found to be safer and quicker, manual condition surveys have been proven to offer preciseness and cost-effectiveness. In the case of low-volume roadway assessment, for which the funds available to asset managers are limited, manual condition surveys are often preferred. Nevertheless, manual condition surveys must address the potential subjectivity of the results. Therefore, agencies could benefit from a system for ensuring quality on manual condition surveys. This paper proposes a framework for assessment of data quality and presents a case study of its implementation in the Northern New Mexico Pavement Evaluation Program. The proposed framework is easily implementable and able to identify potential and actual data collection issues. The framework can be used as part of an asset management program and could be particularly beneficial in the case of low-volume roads.

Design of Biomass Co-firing System Considering Resource Distribution and Transportation Optimization

Biomass resources have huge potential to secure energy supply in next decades with carbon neutral emissions. However, the resources itself are widely scattered diffusely throughout the country, and the capacity of utilization plant highly depends on the quantity of primary resources available. The study focuses on the equilibrium between resource supply and energy demand in Tohoku area in Japan, considering geographical distribution and transportation paths. Woody biomass and agricultural residues are introduced in the study as a co-firing fuel supplied to three coal power stations in Tohoku area. The biomass energy system is modeled and analyzed using both geographic information solver and the roadway condition data. In particular, resource supply such as biomass resource collection, preprocessing before transportation, storage, long distance transportation, and energy conversion to electricity, is modeled and introduced to the system. As a result of the model analysis, a supply curve of biomass resources is obtained, which shows a relationship between procurement cost for power supply and annual electricity production at coal power stations. The supply curve shows that an electricity of 4.3 × 108 kWh/yr can be supplied with the procurement cost of 10 JPY/kWh, and the maximum electricity reaches 12.7 × 108 kWh/yr with the procurement cost of 14 JPY/kWh.

Rating Roads for Motorcyclist Safety

Motorcycles are vastly different from other vehicles on the road: they are highly unstable and provide little protection to users. Because of motorcycle instability, variations in road surfaces and geometry may be more hazardous to motorcyclists than to other road users. Road safety ratings for the entire vehicle fleet, primarily cars, have been applied to roadways in Europe, the United States, and Australia. However, these primarily car-oriented systems have limited value for motorcyclists. This study develops a unique road safety rating system designed for motorcyclists. On the basis of normalized motorcycle crash rates, roads were classified into five safety rating categories, ranging from low risk to severe risk. The new methodology for rating roads was applied to 16 roads in New Jersey, covering 1,099.5 mi (1,769.5 km) of road. Roadways were mapped to create a visual representation of the distribution of safety hazards on the analyzed roads. Of these roads, 19% posed a severe risk to motorcyclists. The majority of the roads mapped (27%) had a medium risk for motorcycles. The statewide crash risk mapping was supplemented by an in-depth site investigation of an area known to be particularly hazardous to motorcyclists, to develop a better understanding of potentially dangerous roadway conditions.

Unified methodology for site-characterization and sampling of highway runoff

Hydrology, roadway traffic conditions, and atmospheric deposition are three essential data categories for the planning and implementation of highway-runoff monitoring and characterization programs. Causal variables pertaining to each data category could be site specific but have been shown to correlate with runoff pollutant loads. These data categories were combined to derive statistical relationships for characterization and prioritization of the respective pollutant loads at highway runoff sites. Storm runoff data of total suspended solids (TSS), total dissolved solid (TDS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) collected from three highway sites in Charlotte, North Carolina, USA, were used to illustrate the development of site-specific highway-runoff pollutant loading models. This unified methodology provides a basis for initial assessment of the pollutant-constituent loads from highway runoff using hydrologic component variables. Improved reliability is achievable when additional traffic and/or atmospheric component variables are incorporated into the basic hydrologic regression model. In addition, operational guidance is suggested for implementing highway-runoff monitoring programs that are subject to sampling and resources constraints.

Optimal Information Location for Adaptive Routing

One strategy for addressing uncertain roadway conditions and travel times is to provide real-time travel information to drivers through variable message signs, highway advisory radio, or other means. However, providing such information is often costly, and decisions must be made about the most useful places to inform drivers about local conditions. This paper addresses this question, building on adaptive routing algorithms describing optimal traveler behavior in stochastic networks with en route information. Three specific problem contexts are formulated: routing of a single vehicle, assignment of multiple vehicles in an uncongested network, and adaptive equilibrium with congestion. A network contraction procedure is described which makes an enumerative algorithm computationally feasible for small-to-medium sized roadway networks, along with heuristics which can be applied for large-scale networks. These algorithms are demonstrated on three networks of varying size.

Methodology SHAKER and the Capacity Analysis of Five Toll Plazas

Modeling traffic at toll collection facilities can assist in computing plaza capacity and performance. It may help planners and operators decide on which lane configurations are appropriate for specific hourly approach volumes and vehicle types. On a network of toll roadways, it can be used to identify bottleneck locations. This is accomplished by comparing a plaza's capacity to the capacity of a highway segment's just downstream. Both the characteristics of the approaching traffic as well as the roadway conditions before and at the plaza come into play. Choosing a lane configuration with an adequate number of dedicated electronic toll collection lanes that match the approaching traffic demand is one key to maximizing the toll plaza throughput. The capacity of a toll lane is simply the lane's average hourly processing rate under queuing conditions as measured in the field. Measurements must take place when there is uniformity in the type of toll collected in the lane as well as uniformity in the type of vehicle being processed. The average hourly processing rates for several categories of traffic and tolling type have been measured in the field and have been collected for this study. Complexity is added to the model when configuring a mixed lane that either provides several methods of toll collection, or provides the same toll collection type to several different categories of customers, or provides toll collection in a manner that is a mixture of these two. SHAKER was developed to address these issues and compute capacities of toll plazas that consist of mixed lanes as well as dedicated lanes. This study also applied the SHAKER methodology to 5 real toll facilities plazas on the Florida Turnpike. The model was both calibrated and validated using these data.