Search

Prediction models have been extensively used in the field of road safety. However, none of these models have yet been particularly applied to injuries related to zero-emission electric vehicles (EVs), which may lead to different outcomes due to their inaudible engines. Using an optimisable classification tree, the aim of this first-ever study was to predict the likelihood of personal injury severities stemming from EV-related crashes on Britain's roads. The prediction model was found to be capable of detecting significant and insignificant factors. These factors provide important insights into how the severity of injuries could be reduced in the future deployment of EVs. Although there was an increased risk for injuries classified as 'slight severity', particularly at lower urban speed limits, several predictors are suggesting that EVs do not pose more of a risk to a certain group. Contrary to popular belief, no convincing evidence was found to suggest that eco-friendly EVs are 'silent killers' for vulnerable road users. [ABSTRACT FROM AUTHOR]

The use of natural river silt treated as a 'waste material' has become the focus of research in the Yellow River flooded area, especially in the field of highway engineering. It is therefore of great significance to study the deformation and stiffness degradation of Yellow River silt (YRS) under long-term cyclic loads. To this end, a series of undrained cyclic triaxial tests on YRS for a large number of cycles (10 000) was carried out using a triaxial apparatus and the effects of confining pressure and cyclic stress ratio on the resilient strain of the YRS were explored. The critical cyclic stress and the critical cyclic stress ratio between the plastic shakedown state and incremental collapse state of the YRS were determined, and the modulus-softening behaviour of the YRS was assessed. The results of this study not only provide theoretical support for the long-term engineering performance of YRS, but also provide theoretical guidance for the cyclic response of all similar types of subgrade soils. [ABSTRACT FROM AUTHOR]

There have been limited efforts to investigate the potential of using detailed trajectory data obtained from connected vehicles and/or other sensors in deriving metrics for use in real-time assessment of traffic safety. This study investigated the use of disturbance metrics for this purpose. The disturbance metrics considered were the number of oscillations (NoO) and a measure of disturbance durations in terms of the time exposed time-to-collision index (TETIndex). The time exposed time-to-collision (TET) has been widely used as a safety surrogate measure, but there is no study on the identification of its thresholds to justify activating plans to mitigate unsafe conditions in real-time operations. This study found a TETIndex of 0.03 and NoO of 10% can be used to recognise unsafe conditions in the case study of this research. Since estimation of the TETIndex requires the location and speed of both leading and following vehicles and therefore cannot be measured accurately with low sample sizes of vehicle trajectories, a regression model was derived to estimate the TETIndex based on speed parameters. It was also found that the investigated disturbance metrics and associated models and thresholds are significantly related to crash occurrence and can thus be used in the activation of transportation management strategies to reduce the probability of unsafe traffic and ease traffic disturbances that have an adverse impact on traffic safety. [ABSTRACT FROM AUTHOR]

Sincere thanks are extended to the following people who reviewed manuscripts submitted to the I Journal of Performance of Constructed Facilities i during the period of July 1, 2021, to June 30, 2022. Hassan Abbasi I Islamic Azad University, South Tehran Branch i A. B. M. Abdullah I Arkansas Department of Transportation i Masato Abe I BMC Corporation i Michael Joseph Abrahams I WSP USA Corp. i Mehmet Ada I Usak University i Jose M. Adam I Universitat Politècnica de València i Süleyman Adanur I Karadeniz Technical University i Hamdy M. Afefy I Tanta University i Mohammad Aghababaei I Texas A&M University i Ihab El Aghoury I Ain Shams University i Emma Marinie Ahmad Zawawi I Universiti Teknologi MARA i Hüseyin Akay I Gazi Universitesi i Zülal Akbay Arama I Istanbul University-Cerrahpasa i Emre Akin I Adnan Menderes Universitesi i Ahmet Emin Aktan I Drexel University i Haluk Aktan I Western Michigan University i Ahmed Sh. [Extracted from the article]

Random Effect (RE) models are used for analyzing data that are non-independent or when data are characterized by a hierarchical structure. In traffic and highway engineering, RE models have been successfully employed to estimate free-flow speed distributions from data containing observations that are naturally nested according to different levels (i.e. direction, sections, roads). Empirical studies conducted on both urban arterials and rural two-lane highways have shown that RE models, by properly accounting for the survey design, are superior to traditional Fixed Effect (FE) models. However, RE models are non-transferable because of the unknown RE value for roads or road sections belonging to a different network or road of the same network that were not originally used to develop the model. In this paper, the transferability of RE models to road sections that were not in the original sample used for model estimation was studied, under the assumption that for these additional sections very few observations are available or can be collected. This problem poses two challenges. First, random effects for the new road sections should be estimated in order to make out-of-sample predictions. Second, the original model formulation makes use of speed quantiles as predictors of the linear model which are not readily available for the new sections. The method proposed estimates an auxiliary model, in which the RE of the original model are correlated to the RE to be defined for the new section, with the former being used to predict the latter. The RE pairs are modeled jointly, taking advantage of their potential mutual correlation. The model coefficients obtained are also validated using a jackknife technique. Results show that the method converges quite fast and that a handful of observations for the new road section are sufficient for good RE estimates. [ABSTRACT FROM AUTHOR]

• Engineering judgment is widely trusted. In road safety the trust may not be deserved. • Engineers are not trained in road safety nor learn it from their own experience. • Engineers must hold safety paramount. Transportation engineers cannot really do so. • It is up to standard committees to strike and informed safety vs. 'utility' balance. Decisions that highway and traffic engineers make significantly affect the safety of road users. The documents that guide highway and traffic engineering practice suggest that many of these decisions be made by 'engineering judgment'. One would like this judgment to be informed by evidence-based anticipation of their likely safety consequences and by a professional ability to balance safety against mobility and other dimensions of 'utility'. I show that these desiderata are largely unfulfilled. The many implications of this finding are discussed. [ABSTRACT FROM AUTHOR]

• A review of research studies about route familiarity in road safety was conducted. • Route familiarity was shown as able to broadly affect the driving behaviour. • Both psychological and economic perspectives revealed this potential influence. • The several implications in the road and traffic engineering practice were shown. • Different criteria for identifying route familiarity were harmonized in a new proposal. Route familiarity can be an important safety-related variable, which is often neglected. A review of previous works highlighting the relationships between route familiarity and road safety in behavioural studies and engineering standards/frameworks has been conducted. Theoretical frameworks supported by experimental results have revealed that driving behaviour can be affected by route familiarity. The latter may lead to distraction and self-confidence; and in turn to more dangerous behaviours after repeated journeys. From an economic perspective, the possible worsening of driving safety performance may be explained by trade-offs with mobility benefits. Route familiarity is also considered in engineering practice. Road design guidelines assuming a "design driver" were suggested as implicitly preserving the safety of familiar/unfamiliar drivers. The mix of familiar and unfamiliar drivers in traffic flow is explicitly considered when computing the design traffic. The safety implications of these matters find only partial confirmation in previous studies focused on involvement in crashes. However, comparing those findings was difficult due to the high variability in measuring the route familiarity itself. An attempt to harmonize the possible identifications of familiarity for future studies, based on previous findings, is proposed. The proposal considers two different scales used for measuring route familiarity: one based on travelling frequency, the other on distance from residence. [ABSTRACT FROM AUTHOR]

The paper presents an overview of safety and insights regarding traffic at highway intermediate cross-sections in the interurban highway network. This overview includes rigid and soft 'one plus one' cross-sections, passing lanes traffic and geometric characteristics, as well as criteria for widening a two-lane highway to form a divided multilane highway. The design overview of intermediate highway cross-sections includes traffic and safety warrants, design speed characteristics and cross-section infrastructure components, including elements that enhance traffic safety. These developments are partly an outcome of the new Israeli geometric design policy and controls for rural (interurban) highways. [ABSTRACT FROM AUTHOR]

The Belt and Road initiative has been gaining attention internationally since its proposal. This study applies complex network theory to the Belt and Road countries’ exchange rate markets by constructing a correlation network for these markets using the detrended cross-correlation coefficient (DCCA cross-correlation coefficient). Results show that the Belt and Road countries’ exchange rate network (BREN) 1 1 Hereinafter referred to as BREN. exhibits a small-world effect and robustness. The network is divided into three clusters by factional analysis. The three clusters correspond to three regions: West Asia, Central Asia and Europe, and Southeast Asia. The cohesion subgroup density between Central Asia and Europe and West Asia is high, and the inter-correlation of the Central Asia and Europe is strong. Moreover, the CNY’s position in the BREN has been significantly improved since the policy was proposed. [ABSTRACT FROM AUTHOR]

Highlights • Investigate the system optimum dynamic traffic assignment problem in parallel network by using point-queue approach. • Extend a graphical solution method to draw the DSO allocation lines. • Three possible optimal allocation lines are analyzed. • A day-based incentive routing strategy is designed to realize DSO. • Conditions that when and how to implement the incentive scheme to realize DSO are derived. Abstract This paper analyzes the dynamic traffic assignment problem on a three-alternative network with day-based incentive routing strategies by using graphical solution method. It is assumed that the cumulative count curve of vehicles is known and that the arrival rate is unimodal. The dynamic system optimum (DSO) allocation lines are first drawn based on calculus of variations. Three possible optimal allocation lines are analyzed. A day-based incentive routing strategy is designed and conditions that when and how to implement the incentive scheme to realize DSO are then derived. Extension to general parallel networks is also given. Examples are presented to demonstrate the effectiveness of the scheme. [ABSTRACT FROM AUTHOR]

This paper presents an investigation into passing lane length and spacing on two-lane highways. Different combinations of length and spacing were examined under various traffic levels using field data and microscopic traffic simulation. Field data from two side-by-side passing lane study sites in Oregon were used to calibrate and validate the traffic simulation program used in this study. The simulation model was then used to evaluate the effect of different passing lane length and spacing combinations on two-lane highway performance. Study results confirmed the general understanding that using longer and/or more frequent passing lanes yields better operational performance. Moreover, at higher traffic levels, a greater passing lane length, a shorter spacing or both are required to achieve the same improvement in performance. Further, results suggest that passing lane length between 0.75 and 2 miles and spacing between 5 and 15 miles provide the highest effectiveness depending on traffic level. A regression model for performance as a function of traffic flow rate, length and spacing of passing lanes was also developed. [ABSTRACT FROM AUTHOR]

Traffic signals at intersections have a significant effect on traffic emissions. They interrupt traffic flow and create additional acceleration and deceleration driving modes. Therefore, the objective of this paper is to perform the optimization process of vehicle delay and exhaust emissions at isolated signalized intersections. Three-leg intersection located in Kafr El-Sheikh City, Egypt was selected in this study. Field delay times were estimated based on vehicle speed and acceleration profiles using GPS device. On-road measurements of vehicle speeds and emissions were collected simultaneously for all movements of all approaches at the selected intersection. The micro-simulation software VISSIM was used to model and analyze the selected intersection. The model was calibrated and validated using the collected data. Signal timing model was developed for the selected intersection and used for optimization of delay time and vehicle emissions. It was found that the changing of signal timing was effective in improving the operational and environmental performance of the traffic signal under study. Also, the results indicated that when the traffic flow rate is higher, the optimal cycle time corresponding to the performance index function increases. Optimization of the delay times and exhaust emissions gives traffic engineers the option of minimizing vehicle emissions in the designing of the signalized intersections or timing a signal system. [ABSTRACT FROM AUTHOR]

• Trajectory data of road users bring about progresses in transportation research. • Wide-area trajectory data are continuous trajectories of vehicles along roadway. • Advances in sensing and computing make tracking at wide-area level possible. • This paper discusses research potentials of wide-area vehicle trajectory data. Trajectory data of road users play a crucial role in transportation engineering and traffic safety research. Previous vehicle trajectory data, including naturalistic driving data, trajectory data captured by drones and traffic cameras, have greatly promoted the research of traffic safety, traffic simulation, and other transportation engineering fields. However, existing technologies in collecting trajectory data are limited their detection range. With the development of the sensing and tracking technologies, it is possible to track the trajectory information of road users at the wide-area level, i.e., the real-time trajectory data of all road users on the entire road. Recently, we published our data sharing platform, Tongji Road Trajectory Sharing (TJRD TS, available online at https://tjrdts.com) Platform, providing our open wide-area vehicle trajectory data for researchers, academics, and road traffic professionals. Advanced vehicle tracking and trajectory splicing technologies, such as millimeter wave radar and edge computing technology, were employed to obtain such wide-area vehicle trajectory data. In this short communication article, we brainstorm ideas of using wide-area vehicle trajectory data in traffic safety research, traffic efficiency research, and connected and autonomous vehicle (CAV) application. We hope this short communication and our published data sharing platform can serve as the steppingstone for those who are interested in road transportation engineering and road safety research using such wide-area vehicle trajectory data. [ABSTRACT FROM AUTHOR]

This study evaluates Iran amongst emerging societies which can be considered as development benchmarks specifically in the field of road safety. The five pillars of road safety development were analyzed within three main layers of the road safety management system consisting of institutional management functions, interventions, and results. The main objective of this study is to introduce a ranking criterion that explains the success in each road safety pillar using the concepts of the managing by result and also to identify best practices within a set of developing countries, focusing on the archived results for Iran. A virtual performance indicator shown by ‘S’ was defined as the success score of each pillar in the decade of action for each country to achieve the targets of decreasing road fatalities. This virtual indicator as well as two other indicator classes (intervention outputs and final outcomes) go into an optimization problem using Data Envelopment Analysis (DEA) approach. It is concluded that the S value shows the quality weight of the actions taken in countries and could be a suitable numeric indicator for benchmarking the best practices. The success of Iran in advancing the interventions in two pillars of safer roads and mobility (safer infrastructure) and safer road users (enhanced enforcement) has been higher than the other activities. The actions needed to be taken in Iran include the development of vehicle safety, the structure of road safety management, and post-crash response in order of preference. This country requires to follow best practices in Turkey and Romania which were identified as benchmark countries for Iran. The target value for the fatality rate per 100,000 population in Iran was earned 12.6. [ABSTRACT FROM AUTHOR]

Hub stations and important lines play key roles in transfers between stations. In this paper, a node failure model is proposed to identify hub stations. In the model, we introduce two new indicators called neighborhood degree ratio and transfer index to evaluate the importance of stations, which consider neighborhood stations’ degree of station and the initial transfer times between stations. Moreover, line accessibility is developed to measure the importance of lines in the bus network. Xiamen bus network in 2016 is utilized to test the model. The results show that the two introduced indicators are more effective to identify hub stations compared with traditional complex network indicators such as degree, clustering coefficient and betweenness. [ABSTRACT FROM AUTHOR]

Vertical alignment, which includes vertical grades and lengths, is a critical aspect of highway design policy that influences safety. A full understanding of the effect of vertical grade and segment length on highway safety can help agencies to evaluate or adjust their design policies regarding vertical alignment design features (grade and length). For this reason, it is useful to assess the current relationships between design policy and safety performance. To address this task, this paper uses data from interstate segments to first establish the relationship between these design features and safety. Safety is expressed in terms of the three different levels of crash severity (fatal, injury, and property damage only). In its analysis, the paper departs from the traditional univariate models (where each crash severity is modeled separately) and instead uses a seemingly unrelated negative binomial (SUNB) technique, a multivariate model that duly accounts for the unobserved shared effects between the different levels of crash severity. In addition, the paper’s models duly recognize and account for the holistic nature of the grade and tangent length effects: the effect of the sum (interaction) of the vertical grade and length is different from the sum of their individual effects. The paper investigates the relationships for rural and urban interstate highway segments. Against the background of the developed models, the paper evaluates current design policies (specifications on vertical alignment grade and length) for similar classes of highways at a number of countries and presents a set of nomograms that feature lines representing points of equal safety performance. These charts can be used by the highway agencies to evaluate and compare their current or possible future highway design policies. [ABSTRACT FROM AUTHOR]

The self-adaptive traffic signal control system serves as an effective measure for relieving urban traffic congestion. The system is capable of adjusting the signal timing parameters in real time according to the seasonal changes and short-term fluctuation of traffic demand, resulting in improvement of the efficiency of traffic operation on urban road networks. The development of information technologies on computing science, autonomous driving, vehicle-to-vehicle, and mobile Internet has created a sufficient abundance of acquisition means for traffic data. Great improvements for data acquisition include the increase of available amount of holographic data, available data types, and accuracy. The article investigates the development of commonly used self-adaptive signal control systems in the world, their technical characteristics, the current research status of self-adaptive control methods, and the signal control methods for heterogeneous traffic flow composed of connected vehicles and autonomous vehicles. Finally, the article concluded that signal control based on multiagent reinforcement learning is a kind of closed-loop feedback adaptive control method, which outperforms many counterparts in terms of real-time characteristic, accuracy, and self-learning and therefore will be an important research focus of control method in future due to the property of “model-free” and “self-learning” that well accommodates the abundance of traffic information data. Besides, it will also provide an entry point and technical support for the development of Vehicle-to-X systems, Internet of vehicles, and autonomous driving industries. Therefore, the related achievements of the adaptive control system for the future traffic environment have extremely broad application prospects. [ABSTRACT FROM AUTHOR]

The A82 is a primary route in Scotland that follows the shoreline of Loch Lomond. Following a landslide in the late 1970s, traffic lights were implemented, limiting vehicles to one-way traffic. A widening scheme was required to restore the two-way carriageway over a 400 m length. This scheme included a six-span 168 m viaduct curved in plan to follow the existing road alignment. The form of the structure was highly influenced by the site topography, the adjacent soil/rock slope profile and the loch shoreline. It aimed to provide an economical, buildable solution while minimising intrusion into the sensitive environment and minimising traffic disruption during construction. To meet these criteria, the design was developed to suit a phased construction. A full-length contiguous piled retaining wall supported the existing carriageway and facilitated installation of a trapezoidal steel-concrete composite box-girder viaduct. Partial construction of the deck slab allowed a temporary switch of traffic, enabling the remainder of the bridge works to be completed on the original road alignment. Once constructed, the 3000 t deck was jacked-up to its permanent position using 82 synchronised hydraulic cylinders. This paper summarises how design and construction of the viaduct was achieved in its challenging environment. [ABSTRACT FROM AUTHOR]

Previous cellular automata (CA) models have been developed for simulating driver behaviors in response to traffic signal control. However, driver behaviors during traffic signal change intervals, including cross/stop decision and speed adjustment, have not yet been studied. Based on this, this paper aims to propose a change interval CA model for replicating driver’s perception and response to amber light based on stopping probability and speed adjusting functions. The proposed model has been validated by exemplified and field cases. To investigate the applicability of the proposed model, macroscopic and microscopic analyses are conducted. Although the macroscopic fundamental diagram analysis reveals only a small decrease in maximum traffic flow rates with considering driver behaviors in change intervals, in the microscopic analysis, the proposed model can present reasonable vehicular trajectories and deceleration rates during slowdown process. [ABSTRACT FROM AUTHOR]

Objective To investigate the extent of a driver’s mental model with irrevocable visual occlusion and analysing the distance to crash. Background Drivers have a mental model of the immediate surroundings which allows them to predict their own as well as others’ travel paths. To navigate safely through traffic, this mental model has to be updated frequently to remain valid. In between information sampling events, the mental model will become outdated over time, as the traffic system is dynamic. Method A simulator study with 22 participants was conducted to investigate the information decay in the mental model. This was implemented by extending visual occlusion until the driver collided with another vehicle or ran off the road, thus providing an estimate of how long it takes until the mental model becomes obsolete. Results An analysis of variance with the factors curve direction, curve radius and traffic showed that curve radius did not influence the distance to crash. Without traffic, drivers veered off the road sooner in right curves. Adding traffic eliminated this difference. Traffic ahead led to a shortened distance to crash. Compared to a tangential travel path from the current lateral position at the time of the occlusion, drivers crashed on average 2.6 times later than they would have, had they not had any mental model of the situation. Conclusions The drivers’ mental representation of the future situation seems to include information on how to act, to alleviate deviations in yaw angle, including and considering the presence of other road users. [ABSTRACT FROM AUTHOR]

Most of the existing operating speed statistical models are applicable to individual design elements, particularly horizontal curves and tangents. A segment approach to operating speed has rarely been followed, with a few exceptions mainly related to the performance assessment of urban and freeway corridors, or design consistency studies using speed profiles built from successive design elements. This study introduces a new model to predict operating speeds in segments of two-lane highways. The maximum operating speed is given by a stochastic frontier function of the average daily traffic and road geometrics; the asymmetric disturbance accounts for the diversity in drivers’ behaviour and vehicle characteristics, allowing estimating any percentile speed. The model was calibrated using probe vehicle data from noncongested roads. The accuracy of the average daily traffic in representing the actual driving conditions was further validated using simultaneous speed-traffic measurements. The new model aims to assist practitioners in the evaluation of design consistency from a macroscopic perspective since the early stages of road planning and design, as well as to support the definition of speed limits at new or existing infrastructures. [ABSTRACT FROM AUTHOR]

Adequate design of composite bridge girders requires accurate determination of stud capacities and demands that develop during force transfer at the steel–concrete interface. This paper focusses on residual stud fatigue capacities and accumulated stud damage in existing bridge girders, following decades of high traffic loading. The paper includes discussion from non-destructive magnetic-particle inspection (MPI) and dye-penetrant testing (DPT) crack investigations on the studs of two existing bridge girders following deck removal. In addition, three destructive fatigue push-out tests are performed on the flanges of an existing high-traffic bridge girder to help understand stud residual fatigue capacity. Historic traffic count data are combined with these destructive and non-destructive tests to provide insight into accumulated bridge damage during many years of traffic loading, and to provide insight into potential conservancies in the current AASHTO stud design provisions. Results from the non-destructive MPI and DPT investigations indicated no detectable fatigue cracks within the studs of the two bridge girders (which were estimated to have seen over 25,000,000 and 38,000,000 truck cycles respectively). Results from all three fatigue tests exceeded the AASHTO design life expectancy of approximately 850,000 cycles (at 11.6 ksi (80 MPa)) by over 2.5 million cycles. This residual fatigue life is over 400% of the expected shear stud fatigue life, even after over 38,000,000 truck cycles estimated during the in-service life of the bridge. The excellent shear stud fatigue performance observed is likely due to additional shear transfer through adhesion and or friction between the concrete deck and steel flange during service loading, which are not considered in the current AASHTO design calculations. [ABSTRACT FROM AUTHOR]

Abstract: Human drivers naturally adapt their behaviour depending on the traffic conditions, such as the current weather and road type. Autonomous vehicles need to do the same, in a way that is both safe and efficient in traffic composed of both conventional and autonomous vehicles. In this paper, we demonstrate the applicability of a reconfigurable vehicle controller agent for autonomous vehicles that adapts the parameters of a used car‐following model at runtime, so as to maintain a high degree of traffic quality (efficiency and safety) under different weather conditions. We follow a dynamic software product line approach to model the variability of the car‐following model parameters, context changes and traffic quality, and generate specific configurations for each particular context. Under realistic conditions, autonomous vehicles have only a very local knowledge of other vehicles' variables. We investigate a distributed model predictive controller agent for autonomous vehicles to estimate their behavioural parameters at runtime, based on their available knowledge of the system. We show that autonomous vehicles with the proposed reconfigurable controller agent lead to behaviour similar to that achieved by human drivers, depending on the context. [ABSTRACT FROM AUTHOR]

Road traffic safety is emerging as an area of increased attention and concern in many countries including India. Safety evaluation by conflict study using surrogate measures is a proactive method which does not require any accident data. Conflict study may be carried out using post encroachment time (PET) as a surrogate measure, where critical conflicts are determined based on certain threshold value of PET. Identifying critical conflicts using a threshold value of PET is good and correct for highways and major roads where traffic follows posted speed, but on highways with mixed traffic for varied speeds this is not correct. It can be seen that conflicts with PET less than the threshold value may not be critical if the speed of conflicting vehicle is less. Similarly, conflicts with PET more than threshold value may also be critical if the speed of conflicting vehicle is high. The speed of conflicting vehicle is also important in evaluating severity of conflict. Hence, the use of PET alone for conflict study is not correct for evaluating safety of intersections on highways where traffic follows varied speeds. Therefore, in the present study, safety evaluation of an unsignalized intersection is carried out using two surrogate measures, PET and the speed of corresponding conflicting through vehicle. A term critical speed is proposed to identify critical conflicts. Critical speed for a particular PET value is determined using stopping/braking distance concept. Results show that there are significant percent of conflicts which are critical at the intersection. This shows that drivers of right-turning vehicles do take risks in accepting small gaps in through traffic at the intersection, which is dangerous. As crossing maneuver depends on length and speed of turning vehicle, the effect of type of turning vehicle has also been studied. Results show that right-turning light motor vehicles are at higher risk compared to two wheelers and heavy vehicles at the intersection. Safety evaluation of such unsignalized intersections may be carried out using this concept. [ABSTRACT FROM AUTHOR]

The objective of this research is to investigate the pavement response of road-bridge transition section without slab under impact load caused by vehicle bumping. The three-dimensional (3D) finite element models (FEM) of road-bridge transition section without slab were developed to simulate the response under impact load. The influence of different parameters (damping ratio, step height, vehicle speed as well as axle load) on the pavement response was investigated. Results indicated that an obvious increase of pavement response was observed with the step height and axle load rising. On the contrary, the rise of vehicle speed and damping ratio led to the decrease of pavement response. In addition, the pavement under impact load exhibited larger response as compared to under static load. Therefore, the phenomenon that static load was considered only in the traditional pavement structure is defective. Finally, the correction coefficients of design index for highway asphalt pavement were proposed to consider the influence of impact load. [ABSTRACT FROM AUTHOR]

Mainline freeway traffic flow control is one of the primary methods of traffic management, which can present the best network situation. In this paper, we integrate variable speed limit (VSL) strategy into the cell transmission model (CTM). Then the implementation of the integrated model on freeway traffic network is discussed. A novel optimal model of controlling freeway traffic flow is proposed for minimizing the total travelling time in the network. A solution algorithm is designed by using a simulation method. Considering the main purpose of the speed limit strategy is to control the mainstream flow, we compare the case where the VSL is used with the one without VSL. A simulation is implemented to show that the control strategy is efficient in describing system's dynamic performance and the dynamic speed limit strategy significantly alleviates congestion. [ABSTRACT FROM AUTHOR]

This empirical study sheds light on the spatial correlation of traffic links under different traffic regimes. We mimic the behavior of real traffic by pinpointing the spatial correlation between 140 freeway traffic links in a major sub-network of the Minneapolis—St. Paul freeway system with a grid-like network topology. This topology enables us to juxtapose the positive and negative correlation between links, which has been overlooked in short-term traffic forecasting models. To accurately and reliably measure the correlation between traffic links, we develop an algorithm that eliminates temporal trends in three dimensions: (1) hourly dimension, (2) weekly dimension, and (3) system dimension for each link. The spatial correlation of traffic links exhibits a stronger negative correlation in rush hours, when congestion affects route choice. Although this correlation occurs mostly in parallel links, it is also observed upstream, where travelers receive information and are able to switch to substitute paths. Irrespective of the time-of-day and day-of-week, a strong positive correlation is witnessed between upstream and downstream links. This correlation is stronger in uncongested regimes, as traffic flow passes through consecutive links more quickly and there is no congestion effect to shift or stall traffic. The extracted spatial correlation structure can augment the accuracy of short-term traffic forecasting models. [ABSTRACT FROM AUTHOR]

The ability and efficiency of abstracting highway operating status are determined by data collection cost, equipment reliability, and other factors. Thus it has always been a significant demand for low installation and maintenance cost, solid and efficient equipment with rational and reliable data analysis methodology, which corporately could provide accurate traffic prediction. This paper proposed a method for obtaining traffic situation based on widely used ETC dedicated short range communication (DSRC) device, and investigated its feasibility for dynamic highway operating status abstracting. In addition, some detailed operating index, such as section average travel time, average travel speed, etc., were estimated, and with these indexes, a highway section congestion degree model and a travel time prediction model were established. Furthermore, a pilot study on Jingjintang Expressway near Beijing was conducted, and the results of DSRC data exploring showed that the proposed traffic condition obtaining method could accurately reflect the actual traffic condition. [ABSTRACT FROM AUTHOR]

As a domain of political intervention, speed is a meeting ground for projects of domination and tactics of emancipation, for logics of exclusion coexisting with various forms of collisions, intersections and amalgamations. Instead of reducing the 'need for speed' to a linear and unequivocal process, this article makes the case for thinking about speed as an arena of conflict, subject to brutal accelerations but also to at least momentary decelerations. Taking the example of Karachi, where road accidents and larger controversies around transport played a prominent role in the violent postcolonial transformations of the city, it argues that from these collisions emerged a form of political power premised on the regulation of traffic flows. It concludes that moving-power always exceeds the initial intentions of those setting it in motion as it simultaneously builds on and disrupts the forces that give every city its vitality, that is, on the vitalism of speed. [ABSTRACT FROM AUTHOR]

As the demand for additional capacity on urban freeways continues to increase, there is a need to better understand how to optimize the lane and shoulder configurations so as to improve capacity without adversely impacting operating speed. The overall objective for this research effort was to identify the operational implications of using reduced lane and shoulder widths on freeways. The operational analysis found speeds 3.5 km=h (2.2 mph) higher for a 3.7 m (12 ft) lane as compared to a 3.4 m (11 ft) lane. The authors developed an equation that can be used to predict speeds per lane for freeway locations with boundary conditions similar to those present in the study database. [ABSTRACT FROM AUTHOR]

This study aimed to develop a secondary crash risk prediction model on freeways using real-time traffic flow data. The crash and traffic data were collected on the I-880 freeway for five years in California, United States. The secondary crashes were identified by a method based on speed contour plot. The random effect logit model was used to link the probability of secondary crashes with the real-time traffic flow conditions, primary crash characteristics, environmental conditions, and geometric characteristics. The results showed that real-time traffic variables significantly affect the likelihood of secondary crashes. These traffic variables include the traffic volume, average speed, standard deviation of detector occupancy, and volume difference between adjacent lanes. In addition, the primary crash characteristics, environmental conditions and geometric characteristics also significantly affect the risks of secondary crashes. The model evaluation results showed that the predictive performance of the developed model was deemed satisfactory. The inclusion of traffic flow variables and random effect increases prediction accuracy by 16.6% and 7.7%, respectively. These results have the potential to be used in advanced traffic management systems to develop proactive traffic control strategies to prevent the occurrences of secondary crashes on freeways. [ABSTRACT FROM AUTHOR]

This paper reviews and classifies the traffic optimisation schemes of current mainline railway into two groups. One is to improve the efficiency of traffic management by providing resolutions for traffic conflicts, while the other is to improve trains’ driving behaviour by providing driver assistance or introducing train automation. Based on a comparison of these two groups, this paper proposes to combine the functions of traffic management and train automation into an integrated optimisation model. This model includes the following contributions. First, in the function of traffic management, this paper explores the flexibility in generating different train running trajectories to prevent potential traffic conflicts. The trajectory can improve traffic flow by avoiding unplanned train stops. This is regarded as a supplementary conflict resolution to train reordering or rerouting or retiming. Second, this paper defines a series of train control commands to determine different intensities of the train’s tractive force and braking force. These commands are seen as the key to train automation. Moreover, a decision-making procedure is introduced to select the most attractive train running trajectory or train control command according to different optimisation objectives. Lastly, this paper proves the importance of bidirectional communication between traffic management and train automation based on a case study. [ABSTRACT FROM AUTHOR]

Increasing individual vehicular traffic is a major concern all around the world. This leads to more and more oversaturated intersections. Traffic signal control under oversaturated condition is a long-lasting challenge. To address this challenge thoroughly, this paper introduces grade separation at signalized intersections. A lane-based optimization model is developed for the integrated design of grade-separated lanes (e.g. tunnels), lane markings (e.g. left turns, through traffic, right turns, etc.) and signal timing settings. We take into account two types of lane configurations. One is conventional surface lanes controlled by signals, and the other is grade-separated lanes. This problem is formulated as a Mixed Integer Linear Program (MILP), and this can be solved using the regular branch-and-bound methods. The integer decision variables help in finding if the movement is on grade-separated or surface lanes, and also the successor functions to govern the order of signal display. The continuous variables include the assigned lane flow, common flow multiplier, cycle length, and start and duration of green for traffic movements and lanes. The optimized signal time settings and lane configurations are then represented in Vissim simulation. Numerical examples, along with a benefit-cost analysis show the good savings of the proposed optimization model for oversaturated traffic conditions. The benefit-cost ratio for installing 4 grade-separated lanes (as a tunnel) at a heavily oversaturated intersection (intersection capacity utilization rate equal to 1.57) exceeds 5.4. [ABSTRACT FROM AUTHOR]

One of the main triggers of traffic congestion on highways is vehicle merging at on-ramps. The development of automated procedures for cooperative vehicle merging is aimed to ensure safety and alleviate congestion problems. In this work, a longitudinal trajectory planning methodology is presented, developed to assist the merging of vehicles on highways; it achieves safe and traffic-efficient merging, while minimizing the engine effort and passenger discomfort through the minimization of acceleration and its first and second derivatives during the merging maneuver. The problem is formulated as a finite-horizon optimal control problem and is solved analytically. This enables the solution to be stored on-board, saving computational time and rendering the methodology suitable for practical applications. The tunable weights, used for taking into account the different optimization criteria, may serve as parameters to match the individual driver’s preferences. The proposed methodology is first developed for a pair of cooperating vehicles, a merging one and its putative leader. Moreover, an alternative solution procedure via a time-variant Linear-Quadratic Regulator approach is also presented. A Model Predictive Control (MPC) scheme is utilized to compensate possible disturbances in the trajectories of the cooperating vehicles, whereby the analytical optimal solution is applied repeatedly in real time, using updated measurements, until the merging procedure is actually finalized. Subsequently, the methodology is generalized for a set of vehicles inside the merging area. Various numerical simulations illustrate the validity and applicability of the method. [ABSTRACT FROM AUTHOR]

Traffic flow pattern identification, as well as anomaly detection, is an important component for traffic operations and control. To reveal the characteristics of regional traffic flow patterns in large road networks, this paper employs dictionary-based compression theory to identify the features of both spatial and temporal patterns by analyzing the multi-dimensional traffic-related data. An anomaly index is derived to quantify the network traffic in both spatial and temporal perspectives. Both pattern identifications are conducted in three different geographic levels: detector, intersection, and sub-region. From different geographic levels, this study finds several important features of traffic flow patterns, including the geographic distribution of traffic flow patterns, pattern shifts at different times-of-day, pattern fluctuations over different days, etc. Both spatial and temporal traffic flow patterns defined in this study can jointly characterize pattern changes and provide a good performance measure of traffic operations and management. The proposed method is further implemented in a case study for the impact of a newly constructed subway line. The before-and-after study identifies the major changes of surrounding road traffic near the subway stations. It is found that new metro stations attract more commute traffic in weekdays as well as entertaining traffic during weekends. [ABSTRACT FROM AUTHOR]

The article is dedicated to the presentation of a vision-based system for road vehicle counting and classification. The system is able to achieve counting with a very good accuracy even in difficult scenarios linked to occlusions and/or presence of shadows. The principle of the system is to use already installed cameras in road networks without any additional calibration procedure. We propose a robust segmentation algorithm that detects foreground pixels corresponding to moving vehicles. First, the approach models each pixel of the background with an adaptive Gaussian distribution. This model is coupled with a motion detection procedure, which allows correctly location of moving vehicles in space and time. The nature of trials carried out, including peak periods and various vehicle types, leads to an increase of occlusions between cars and between cars and trucks. A specific method for severe occlusion detection, based on the notion of solidity, has been carried out and tested. Furthermore, the method developed in this work is capable of managing shadows with high resolution. The related algorithm has been tested and compared to a classical method. Experimental results based on four large datasets show that our method can count and classify vehicles in real time with a high level of performance (>98%) under different environmental situations, thus performing better than the conventional inductive loop detectors. ©2016 SPIE and IS&T [DOI: 10.1117/1.JEI.25.5.051207] [ABSTRACT FROM AUTHOR]

• Studied the heat-reflective coating of asphalt pavement. • Systematically studied the durability of heat-reflective coating. • Investigated the effect of anti-skid particles on the cooling performance of coating. • Studied the optimal dosage of anti-skid particles. Reducing high temperature rutting on asphalt pavement is of great importance to improve the quality of pavement engineering and road traffic safety. In laboratory and field tests, this study investigates the cooling performance and optimal dosage of heat-reflective coatings. The temperature-change resistances, water stabilities, abrasion resistances, and skid resistances of six colored heat-reflective coatings were studied. Among the differently colored coatings, the red coating demonstrated the best cooling performance, with a maximum cooled temperature of 13.2 °C. The colored heat-reflective coatings showed good temperature-change resistance, water stability, and abrasion resistance. At dosages of 0.35 and 0.55 kg/m2, the heat-reflective coating met the specification requirements of skid resistance; meanwhile, the coating added at 0.75 kg/m2 achieved the highest cooling performance but failed to meet the required skid-resistance standards. After adding anti-skid particles, the skid resistance was improved while the cooling performance was hardly affected. The optimal dosage of anti-skip particles was 0.3 kg/m2. [ABSTRACT FROM AUTHOR]

The aims of this article are to demonstrate the successes and failures of the £100 million London Cycle Network plus project and to discuss the standard of the highway engineering schemes delivered, particularly in relation to their overall effect on ride quality as defined by the cycling level of service assessment set out in the 2014 London cycling design standards. By highlighting areas where changes could have been made to improve the delivery of the project, it is hoped that lessons can be learnt for future projects of this type. The design approaches of each of London's 33 local authorities were cross-referenced against cycling growth and pedal cycle collisions. From the analysis, the project is shown to have had a positive impact on promoting cycling growth in central London but little identifiable impact on collisions. The article also shows how a reliance on shared-use footways as a design practice could reduce the propensity for people to cycle. As a conclusion, it is suggested that ride quality should be the primary measure of success even if, in reality, the cost of delivering this and the impact it may have on other road users may render the highest levels of service difficult to achieve at present. The paper is relevant to all those seeking to manage or set up major transport projects with time-constrained objectives. It will be of particular interest to those involved in the planning or delivery of cycling infrastructure. [ABSTRACT FROM AUTHOR]

Planners and economists generally accept that housing market values increase with proximity to transportation facilities through the provision of improved access to activity locations. While the market benefits of rail station access are well-documented, inconsistent and insufficient methods have led to limited agreement on the true value associated with this locational amenity. Far fewer hedonic price studies have assessed the influence of bike facility access on housing sales prices, and those that have generally analyze cross-sectional data. In this study, we estimated a spatial hedonic model using a bootstrapped pseudo panel to determine the joint impact of network proximity to bike lanes and off-street multi-use paths, as well as light rail and streetcar stations, on housing sales in Portland, Oregon, from 2002 to 2013. Our findings revealed housing sales prices increased as network distance to the nearest light rail transit and streetcar station decreased. Likewise, owner-occupied single-family and multifamily housing sales rose in conjunction with reduced street network access to regional multi-use bike paths; however, improved proximity to on-street bike lanes negatively affected housing values. In sum, we believe these findings may help to inform non-automotive transportation infrastructure financing mechanisms that rely on rising property values. [ABSTRACT FROM AUTHOR]

This paper proves that mobile phone usage data is an easy to use, cheap and most importantly, reliable predictor of motorway incidents. Using econometric modelling, this paper provides a proof of concept of how mobile phone usage data can be utilised to detect motorway incidents. Greater Amsterdam is used here as a case study and the results suggest that mobile phone usage data can be utilised for the development of an early warning system to support road traffic incident management. [ABSTRACT FROM AUTHOR]

This paper proposes a self-adaptive interactive navigation tool (SAINT), which is tailored for cloud-based vehicular traffic optimization in road networks. The legacy navigation systems make vehicles navigate toward their destination less effectively with individually optimal navigation paths rather than network-wide optimal navigation paths, particularly during rush hours. To the best of our knowledge, SAINT is the first attempt to investigate a self-adaptive interactive navigation approach through the interaction between vehicles and vehicular cloud. The vehicles report their navigation experiences and travel paths to the vehicular cloud so that the vehicular cloud can know real-time road traffic conditions and vehicle trajectories for better navigation guidance for other vehicles. With these traffic conditions and vehicle trajectories, the vehicular cloud uses a mathematical model to calculate road segment congestion estimation for global traffic optimization. This model provides each vehicle with a navigation path that has minimum traffic congestion in the target road network. Using the simulation with a realistic road network, it is shown that our SAINT outperforms the legacy navigation scheme, which is based on Dijkstra's algorithm with a real-time road traffic snapshot. On a road map of Manhattan in New York City, our SAINT can significantly reduce the travel delay during rush hours by 19%. [ABSTRACT FROM PUBLISHER]

The current method for the analysis of sight distance for left-turn vehicles at signalized intersections assumes that all component variables are deterministic. This paper presents a probabilistic approach based on such random variables as major-road speed, time gap required for left-turn vehicle, vehicle width, lateral position of left-turn vehicle, distance between driver eye of left-turn vehicle and its front, and lateral and longitudinal positions of positioned opposing left-turn vehicle. A safety margin is defined as the difference between available and required sight distances. Relationships for the mean and standard deviation of the safety margin were developed using the first-order second-moment (FOSM) method. This method identifies the offset (distance between left edge of the left-turn lane and right edge of the opposing left-turn lane) at signalized intersections for a desired probability of noncompliance based on intersection and traffic characteristics. The proposed reliability method was validated using Monte Carlo simulation, and design graphs were established. The results show that the deterministic method provides very conservative offsets and that the offset is most sensitive to vehicle width and lateral distance-related variables and less sensitive to longitudinal distance-related variables. [ABSTRACT FROM AUTHOR]

In previous studies, little attention has been paid to developing methods for estimating passenger car equivalent (PCE) factors under oversaturated conditions. This paper presents a new method to estimate PCE factors for heavy vehicles based on the assumption that backward wave velocities keep consistent under oversaturated conditions. As the variations of backward wave velocities in mixed flows will be minimal if the traffic stream is uniform, a minimum relative standard deviation optimising model is given based on backward wave velocity. The traffic data drawn from I-80 datasets provided by the next generation simulation are utilised to analyse this method and prove the assumption. In view of the limitation of empirical data, Vissim microscopic traffic software is used to simulate oversaturated traffic flow under different percentages of heavy vehicles. The results show that the effects of heavy vehicles under oversaturated conditions are greater than those under free-flow conditions and the proportion of heavy vehicles has a major impact on the PCE factors. [ABSTRACT FROM AUTHOR]