Roadway Intersections Research Articles

CPS Architecture Design for Urban Roadway Intersections Based on MBSE

CPS Architecture Design for Urban Roadway Intersections Based on MBSE

Design of Automated Bascule Bridge and Collision Avoidance with Water Traffic

Abstract The development of movable bridges is a modern technological advancement that requires the integration of multi-disciplinary concepts such as control, automation, and design. In order to demonstrate how a collision avoidance system works, this research offers the design of an automated double-leaf bascule bridge with a pulley-rope moving mechanism and Pratt truss. The bridge is created where a settled railway or roadway intersection of a navigable stream cannot attain a steep profile. The design took into account the length, height, and width of the bridge as well as automatic ship identification and scaffold leaf movement activity for ship crossing. For the safe passage of cars on the bridge and for stopping vehicles during bridge movement, the system includes a collision avoidance control system and an automated road barrier system. After sensor adjustment, the model bridge’s performance under test produced results that were adequate, with a success rate of 100%.

Research on a Speed Guidance Strategy for Mine Vehicles in Three-Fork Roadways Based on Vehicle–Road Coordination

Aiming at the traffic congestion problem of mining vehicles in the intersection area of three-fork roadways in coal mines, this paper proposes a speed guidance strategy based on a vehicle–road cooperative environment to adjust the running state of mining vehicles in the three-fork roadway system. The proposed speed guidance strategy can realize the safe and effective passage of underground mining vehicles to the greatest extent. Taking a three-fork roadway in a coal mine as an actual case, the operation of mining vehicles in the three-fork roadway is optimized and scheduled. Through the joint simulation of PTV VISSIM 4.3 traffic simulation software and PYTHON 3.7, the travel time, number of queuing vehicles, and delay time of mining vehicles passing through the three-fork roadway entrance under the two conditions of no speed and speed guidance in the coal mine are simulated and compared. The results show that after using the proposed speed guidance strategy for scheduling, mining vehicles can quickly pass through the three-fork roadway intersection. The travel time is reduced by 18.4%, the number of queuing vehicles is reduced by 41.5%, and the delay time is reduced by 24.1%, which effectively improves the transportation efficiency of underground mining vehicles.

Quadrant Roadway Intersections: Tradeoffs between Control Delay Savings and Extra Travel Time

A quadrant roadway intersection (QRI) reduces congestion relative to a four-phase intersection. (Note: this study relates to traffic systems where vehicles drive on the right-hand side of the road.) It does this by removing left-turn traffic from the main intersection, resulting in a two-phase signal. Nevertheless, there is a lack of clear understanding of the tradeoffs between savings in control delay versus extra travel time experienced by the rerouted movements. This research compared the operational performance of five QRI designs with the counterpart conventional intersection (CI) under various traffic demand scenarios via TransModeler microsimulation modeling. Three measures-of-effectiveness (MOEs) were employed: time-in-system (TIS), control delay, and intersection capacity utilization. Simulation results show that all QRI designs outperform CI design for all three MOEs under all demand scenarios. QRIs with direct left-turn design have a smaller average TIS than those with loop left-turn design, indicating that savings in control delays did not offset the extra travel times. Under a relatively low demand condition, a single QRI design can generally balance the tradeoffs between control delay and extra travel time. Under a high demand scenario, a dual or full QRI with direct left-turns is preferred, since it reroutes or partially reroutes left- and right-turn traffic to secondary intersections, thus the main intersection has a lower capacity utilization and can accommodate more through-traffic demands than CI, single QRI, and dual or full QRIs with loop left-turns.

Control Mechanism and Support Technology of Deep Roadway Intersection with Large Cross-Section: Case Study

Conventional bolt–shotcrete support technology is usually single-layered, which does not meet the requirements of strength and stiffness for roadway support. Therefore, in this paper, new combined support technology, including a multiple-layered staggered dense arrangement of bolts, multiple-layered laying of steel meshes, multiple-layered pouring of shotcrete, strengthening support of long cables, and full cross-section grouting, is proposed. Specifically, the following new combined support technology process is proposed: first layer of shotcrete (80 mm), first layer of mesh, first layer of bolt, second layer of shotcrete (50 mm), second layer of mesh, second layer of bolt, reinforced cable, third layer of shotcrete (50 mm), and grouting. The results show the following: (1) In the system of a superimposed coupling strengthening bearing arch, compared to a cable bearing arch, changing the support parameters of the bolt bearing arch can significantly vary the bearing capacity. A range of bolt spacing between 0.4 m and 0.7 m is more conducive for a high performance of the bearing capacity of the superimposed coupling strengthening bearing arch. (2) With the increase in the single-layer shotcrete thickness (from 50 mm to 100 mm), the bearing capacity of the shotcrete structure increased rapidly in the form of a power function. (3) After the multi-level bolt–shotcrete support structure was adopted, the ring peak zone of the deviatoric stress of the surrounding rock at the roadway intersection was largely transferred to the shallow part, and the plastic zone of the surrounding rock of the roadway was reduced by 43.3~52.3% compared to that of the conventional bolt–shotcrete support. The field practice model showed that the final roof-to-floor and rib-to-rib convergences of the roadway intersection were 114 mm and 91 mm after 26 days, respectively. The rock mass above the depth of 3 m of the roadway’s roof and sides was complete, the lithology was dense, and there was no obvious crack. The new technology achieves effective control of a deep roadway intersection with a large cross-section.

A Random Parameters Approach to Investigate Injury Severity of Two-Vehicle Crashes at Intersections

Roadway intersections are crash-prone locations and, hence, ensuring the safety of road users at intersections has been a major concern for transportation professionals. It is critical to identify the risk factors that contribute to severe crashes at intersections to implement the appropriate countermeasures. Greater emphasis is needed on two-vehicle crashes since they represent the majority of intersection crashes. In this study, a random parameter ordinal probit model was developed to estimate the contributing factors of injury severity of two-vehicle crashes at intersections. Nine years of intersection crash data in Wyoming were analyzed in this model. The study involved the investigation of the influence of a set of intersection, drivers, environmental, and crash characteristics on crash injury severity. The results demonstrated urban and signalized intersections were related to lower severity levels. In addition, higher pavement friction is more likely to be associated with less severe crashes. Crashes that involved drivers who are females or impaired and crashes on weekends were associated with higher severity levels. Intersection crashes that occurred on non-dry road surfaces, in adverse weather conditions, or that involved large vehicles, or out-of-state drivers were less likely to be severe.

Seepage Law of Nearly Flat Coal Seam Based on Three-Dimensional Structure of Borehole and the Deep Soft Rock Roadway Intersection

Exploring the evolution characteristics of gas seepage between boreholes during the drainage process is critical for the borehole’s layout and high-efficiency gas drainage. Based on the dual-porous medium assumption and considering the effect of stress redistribution on coal seam gas seepage characteristics, a coal seam gas seepage model with a three-dimensional roadway and borehole crossing structure has been established and numerically calculated, concluding that the coal seam is between the drainage boreholes. The temporal and spatial evolution characteristics of gas pressure and permeability help elucidate the gas seepage law of the nearly flat coal seam associated with the deep soft rock roadway and borehole intersection model. The results indicate that: (1) The roadway excavation results in localized stress in some areas of the surrounding rock, reducing the strength of the coal body, increasing the expansion stress, and increasing the adsorption of gas by the coal body. (2) Along the direction of the coal seam, the permeability decreases initially and then increases. The gas pressure in the coal seam area in the middle of the borehole is higher than the pressure in the coal seam around the borehole, and the expansion stress and deformation increase, reducing the permeability of the coal body; when near the next borehole, the greater the negative pressure, the faster the desorption of the gas attracts the matrix shrinkage effect and causes the coal seam permeability rate to keep increasing. (3) The improvement of gas drainage with the overlapping arrangement of two boreholes firstly increases and then decreases as time goes on. (4) When the field test results and numerical simulation of the effective area of gas extraction are compared, the effectiveness of the model is verified. Taking the change of the porosity and the permeability into the model, it is able to calculate the radius of gas drainage more accurately.

Safety and Operational Effectiveness of Protected Only Versus Protected/Permitted Left-Turn Signal Phase

Roadway intersection fatalities account for around 24% of total traffic fatalities each year, with left-turning vehicles associated with most of these crashes. To manage left-turning movements, various left-turn signal phases like protected only (PO), protected/permitted left-turn (PPLT), and flashing yellow arrow (FYA) are currently in use. However, their overall effectiveness has not been well established. The paper evaluates the safety and operational effectiveness of PO over PPLT left-turn signal phase using sample intersections from Louisiana. A total of 151 signalized intersections with uniform left-turn signal phases at all of their approaches were selected. Crash data recorded over five years at those intersections comprising a total of 13,278 crashes, including 1,275 left-turn crashes, were collected. A crash modification factor (CMF) was developed using the negative binomial model (NBM) to assess the safety benefits of PO over PPLT. The Highway Capacity Manual 6th Edition (HCM 6) control delay field measurement technique was used for the operational analysis. The study first developed CMFs for total crashes and only left-turn crashes at various severity levels. CMF of PO over PPLT revealed that PO significantly reduced all severity levels of left-turn crashes by more than 50%, however, it was only able to reduce injury and fatal total crashes. Second, the study found average control delay at PO (50.69 s/vehicle) significantly higher than at PPLT (46.04 s/vehicle). The difference in delay was only significant during the morning peak hour. Overall, from both safety and operation perspectives, the results indicate that PO performs better than PPLT.

Examining the efficacy of improved traffic signs and markings at flashing-light-controlled grade crossings based on driving simulation and eye tracking systems

The majority of the collisions at grade crossings occurred at flashing-light-controlled grade crossings. Understanding drivers’ behaviors and visual performances in the process of approaching the crossings is the foundation of improving crossing safety. This study aims at utilizing driving simulation and eye tracking systems to investigate the efficacy of improved traffic signs and pavement markings (PSM) at flashing-light-controlled grade crossings. The improved signs and markings were modeled in a driving simulation system and tested with a series of flashing light trigger time (FLTT) ranging from 2 s to 6 s with 1 s interval increment. Foggy conditions and drivers’ genders and vocations were considered in experiment design. Thirty-six fully-licensed drivers between 30 and 48 years participated in the experiment. Several eye-movement and behavioral measures were adopted as reflections of the subjects’ performances, including the first fixation time on signs and signals and distance to stop line, total fixation duration, compliance rate, stop position, average speed at the stop line, maximum deceleration rate and brake response time. Results showed that compared with traditional grade crossings signs and pavement markings, drivers could perceive signs timelier and fixate on the flashing-light signal earlier in PSM, especially in the scenarios of earlier FLTTs. The improvement in fixation performance and sign design contributed to a higher stop compliance rate. Importantly, it was found that drivers would hesitate to decide whether to stop or cross facing with flashing red lights, which is similar to the dilemma zone of roadway intersections. Drivers were more likely to fall into the dilemma zones when FLTT was <4 s. When FLTT was 2 s, it was particularly difficult to stop in front of the stop line. Moreover, under a foggy condition, drivers had a difficulty in searching signs and had a longer brake response time compared with a clear condition. For the characteristics of drivers, male drivers had longer fixation duration on signs than females. Professional drivers had a higher maximum deceleration rate compared with non-professional drivers. Above findings implied that improved traffic signs and markings would have a potential to improve traffic safety and deserve a field implementation in the future.

Safe Operations at Roadway Junctions - Design Principles from Automated Guideway Transit

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;This paper describes a system-level view of a fully automated transit system comprising a fleet of automated vehicles (AVs) in driverless operation, each with an SAE level 4 Automated Driving System, along with its related safety infrastructure and other system equipment. This AV system-level control is compared to the automatic train control system used in automated guideway transit technology, particularly that of communications-based train control (CBTC). Drawing from the safety principles, analysis methods, and risk assessments of CBTC systems, comparable functional subsystem definitions are proposed for AV fleets in driverless operation. With the prospect of multiple AV fleets operating within a single automated mobility district, the criticality of protecting roadway junctions requires an approach like that of automated fixed-guideway transit systems, in which a guideway switch zone “interlocking” at each junction location deconflicts railway traffic, affirming safe passage. The analogous AV protection safety subsystem is defined as fail-safe equipment that monitors roadway intersections and junctions, communicates traffic signal status, perceives and communicates alerts and signals to AV connected vehicles concerning potential unsafe conditions, and performs related primary safety functions. Conclusions are drawn that the AV protection roadway intersection functions must be performed by local roadside equipment dedicated to protecting each roadway intersection and junction. Further, it is concluded that the communications technology connecting the infrastructure with the vehicle to perform this vital, fail-safe protection should meet specific functional and performance criteria.&lt;/div&gt;&lt;/div&gt;

Modelling traffic flow emissions at signalized intersection with PTV vissim

The effect of roadway intersection design is strictly linked to a reduction in traffic congestion, fuel consumption and emissions in an urban area. This paper presents a comparative result of the typical four-legged intersection and roundabout operational performance for effective management. Accordingly, a computer model for estimation traffic emissions for two kinds of intersections is created. This study presents a detailed analysis and modelling traffic flow emissions using PTV vissim software and methodology with reasonable solutions to plan a road intersection.

A study on source identification of gas explosion in coal mines based on gas concentration

When the gas explosion occurs in the mine, it is essential to determine in time whether the ventilation system is damaged and trace the explosion location and time to develop an emergency rescue plan and conduct rescue work. In this study, a method to trace the source of explosion by monitoring catastrophic gas concentrations, based on the one-dimensional unsteady flow differential equation, an unsteady flow model for the transport of catastrophic gas in the ventilation network was established. Further, the change laws of catastrophic gas concentrations at roadway intersections were analyzed in combination with the nodal air volume balance law in the ventilation network theory. Finally, we used the particle swarm optimization (PSO) algorithm to invert the gas explosion source point and time in conjunction with the catastrophic gas concentration monitoring data at the monitoring point. Herein, an instantaneous release tracer gas was used instead of a catastrophic gas after a gas explosion, and a concentration monitoring experiment was carried out in a full-size experimental roadway. The inversion results show that the PSO can invert the location and time of the explosion source and simultaneously assess the damage status of dampers within the ventilation network. Note that the root mean square error between the inversion and measured results was less than 1, proving the reliability of the inversion results.

A Novel True Triaxial Apparatus for Simulating Strain Bursts Under High Stress

This paper introduces a new high-pressure servo true triaxial rockburst experimental apparatus that can realize multi-face rapid unloading in the horizontal direction. The apparatus is used to simulate different types of strain burst phenomena in deep underground engineering, such as those at roadways, roadway intersections, and pillars with three and four free faces. In the research and development process, apparatus technologies were included to overcome five key challenges: rapid unloading under high pressure, loading gap removal fixture, three-way loading alignment, symmetrical loading, and system stability after unloading. The apparatus is used to carry out multi-face unloading strain burst experiments and can fully satisfy the experimental requirements. The entire strain burst process is recorded using a high-speed camera. The apparatus can provide experimental support for strain burst mechanism research and an experimental basis for different types of strain burst research.

Development of a Composite Sustainability Index for Roadway Intersection Design Alternatives in the UAE

Many studies have been carried out to evaluate the sustainability of transportation systems, but little attention has been given for the design of roadway intersections. This study aimed to establish a framework and develop a tool to assess the sustainability of roadway intersections from a road-user perspective. Sustainability indicators at the strategic level were extracted from the literature and were utilized with relative weights to develop economic, environmental, and social indices that would be combined into a composite sustainability index (CSI) tool. The tool was applied to four case studies of intersections in Al Ain, United Arab Emirates. For each case study, the sustainability of fifteen design alternatives was evaluated for different scenarios of traffic volume and operational speed. Dimensional indices and the overall CSI were determined using the Multi-Criteria Decision Making method. Results indicated that traffic volume had a significant impact on intersection sustainability ranking, while the effect of operational speed was insignificant. Moreover, weight assignment had an effect on determining the most sustainable design alternative, where the best alternatives of the dimension with the major weight would most likely be the most sustainable. The developed tool would assist decision-makers in other cities to assess intersection projects that correspond to their regional goals.

Numerical Simulation of Wind Changes after Turning at T-shaped Roadway Intersection

Modeling and numerically simulating the intersection of semicircular arch and rectangular cross-section under different air inlet directions, studying the law of wind flow and the location of the average wind speed point, and providing a basis for the deployment of wind speed sensors. Through simulation, it is found that the influence of wind speed on wind flow change is very small. The law of wind flow change under different wind speeds is consistent, and the distance between the average wind speed point and the tunnel wall is also consistent. Along the direction of wind flow, the flow field near the roof and the side with larger air volume is relatively stable, which is suitable for the arrangement of wind speed sensors.

Geometric effect analysis of highway-rail grade crossing safety performance

Highway-rail grade crossings (HRGCs) are where a roadway and railway intersect at the same level. Safety at HRGCs has been identified as a high-priority concern among transportation agencies, but there has been little research on the effects of HRGC geometric parameters on their safety performance. This paper evaluates the effects of HRGC geometric parameters on crash occurrence and severity likelihoods. The competing risk algorithm is selected to simultaneously analyze crash occurrence and severities. Four main HRGC geometric factors, along with other contributors, are investigated at 3,194 public HRGCs in North Dakota. This study focuses primarily on four geometric features of an HRGC: (1) acute crossing angle, (2) number of tracks (indicator of crossing width), (3) the roadway distance between the HRGC and the signalized intersection, and (4) number of highway lanes. Distance to the nearest roadway intersections and highway-railway crossing angles are map-based calculations drawn from geographic information systems (GIS). The findings are: (1) all contributors tested in this study, including highway characteristics, traffic exposures from both railway and highway, and the four geometric features, significantly affect at least one crash severity level; (2) all contributors significantly impact crash frequency except for the distance between crossings and the nearest roadway intersection; and (3) geometric parameters’ long-term effects on cumulative probability of crash severity and occurrence over 30 years is also evaluated. Crossings with three main tracks contribute the highest long-term crash probabilities.

Numerical Analysis of Bolt Support at Roadway Intersection in Yanghui Mine, Vietnam

The stress of surrounding rock at roadway intersection is complex. U-shaped steel support has been used at the roadway intersection of Yanghui Mine in Vietnam, but there are many problems, such as blocked ventilation and limited passing capacity. In this paper, FLAC3D numerical simulation software is used to simulate the support effect of U-shaped steel and bolt based on the field data of Yanghui Mine. The deformation of roof, floor and two sides are compared. The results show that the bolt support can be applied to the intersection of roadways in the mine to improve the support of the mine.

Chapter 11 Coal mining subsidence in the UK

Abstract One of the geohazards associated with coal mining is subsidence. Coal was originally extracted where it outcropped, then mining became progressively deeper via shallow workings including bell pits, which later developed into room-and-pillar workings. By the middle of the 1900s, coal was mined in larger open pits and underground by longwall mining methods. The mining of coal can often result in the subsidence of the ground surface. Generally, there are two main types of subsidence associated with coal mining. The first is the generation of crown holes caused by the collapse of mine entries and mine roadway intersections and the consolidation of shallow voids. The second is where longwall mining encourages the roof to fail to relieve the strains on the working face and this generates a subsidence trough. The ground movement migrates upwards and outwards from the seam being mined and ultimately causes the subsidence and deformation of the ground surface. Methods are available to predict mining subsidence so that existing or proposed structures and land developments may be safeguarded. Ground investigative methods and geotechnical engineering options are also available for sites that have been or may be adversely affected by coal mining subsidence.

Intersections and Non-Intersections: A Protocol for Identifying Pedestrian Crash Risk Locations in GIS.

Intersection and non-intersection locations are commonly used as spatial units of analysis for modeling pedestrian crashes. While both location types have been previously studied, comparing results is difficult given the different data and methods used to identify crash-risk locations. In this study, a systematic and replicable protocol was developed in GIS (Geographic Information System) to create a consistent spatial unit of analysis for use in pedestrian crash modelling. Four publicly accessible datasets were used to identify unique intersection and non-intersection locations: Roadway intersection points, roadway lanes, legal speed limits, and pedestrian crash records. Two algorithms were developed and tested using five search radii (ranging from 20 to 100 m) to assess the protocol reliability. The algorithms, which were designed to identify crash-risk locations at intersection and non-intersection areas detected 87.2% of the pedestrian crash locations (r: 20 m). Agreement rates between algorithm results and the crash data were 94.1% for intersection and 98.0% for non-intersection locations, respectively. The buffer size of 20 m generally showed the highest performance in the analyses. The present protocol offered an efficient and reliable method to create spatial analysis units for pedestrian crash modeling. It provided researchers a cost-effective method to identify unique intersection and non-intersection locations. Additional search radii should be tested in future studies to refine the capture of crash-risk locations.

A CASE FOR IMPLEMENTING SELF-ORGANISING TRAFFIC SIGNAL CONTROL ON SOUTH AFRICAN ROADS

Traffic signal optimisation may lead to the alleviation, to some extent, of urban traffic congestion, particularly by using real-time data rather than expected traffic flow data. Recent advances in radar technology have made it possible to observe detailed traffic flow data in and around roadway intersections in real time. The notion of self-organisation has relatively recently been proposed as a promising alternative to improve the effective allocation of green time, particularly under lighter traffic conditions. A fixed-time control strategy and seven self-organising algorithms are compared in a microscopic traffic simulation model of a provincial road in the Western Cape province of South Africa. Actual arrival rates are used as input for the model, while the algorithms are compared using six performance measure indicators, under both light and moderate traffic conditions. The results are used to make a case for the adoption of self-organising traffic signal control algorithms, especially under conditions of light to moderate traffic densities, since this can lead to significant improvements in traffic flow in terms of delay time, vehicle stops, and time spent travelling at unacceptably slow speeds through the road network.