Grade Separation Research Articles

Overview on the Constructional Dynamics Types of Load on a Flyover

Flyovers or grade separators are bridges built over a traffic intersection to allow people to literally ‘fly over’ the traffic. Flyovers were required on ring roads meeting arterial interchanges, over rivers (“where they are called bridges") or across railway lines. In the past, some flyovers were constructed in different urban locations in India.Thus it is necessary to construct the flyover which is sustainable. Quality and structural design matters a lot, otherwise constructing a flyover is just the waste of money. This paper present the overview of flyover, the constructional procedure of flyover as well as the types of load on the flyover.

Selection of at-grade highway-rail crossings for grade separation

ABSTRACT Highway-rail at-grade crossings (HRGCs) are critical spatial locations of utmost importance for transportation safety. Using the national HRGC inventory database and 5 years of accident data in Oklahoma, a data-driven hierarchical evaluation process was developed for identifying and prioritizing potential HRGCs as candidates for grade separations, which includes four sequential levels of analyses: the practice guidelines, hazard index-based ranking, safety analysis, and full investment analysis. Various types of benefits, in terms of traffic safety, travel time, vehicle operating cost, and environment, were considered. The top-ranked HRGCs were identified and their ranking results were compared among the different methods. The prioritization results were mostly consistent while with several exceptions. This study relied on existing analysis tools and developed a comprehensive while practical sequential prioritization process, which can be directly implemented at state highway agencies for statewide selection of grade separation projects.

A simulation-based evaluation of BRT systems in over-crowded travel corridors: a case study of Cairo, Egypt

This paper examines the performance of bus rapid transit (BRT) systems in over-crowded travel corridors. A case study of King Faisal Street in Greater Cairo Region GCR, Egypt, was adopted. A simulation model was developed using PTV VISSIM simulation platform for the study area. A data collection effort was exerted to collect operational traffic data required for model development/calibration. As BRT systems share the roadway with other modes of travel (vehicles, pedestrians, etc.), handling conflicts is a major challenge that faces operations, especially in over-crowded travel corridors. Four BRT scenarios were developed with different conflict treatment methodologies (vehicle/BRT conflicts at U-turns and vehicle/passenger conflicts near BRT stations), varying from signal control at each BRT station (scenario 1) to complete grade separation (scenario 4). Each of the developed scenarios was thoroughly assessed based on disaggregated segment travel times, aggregated corridor travel times, capacity to accommodate travel demand, and corridor level of service. A wide range of results was reported for the impact of the proposed systems on corridor traffic operations varying from 80% increase in overall travel time (scenario 1) to 18% reduction (scenario 4). Such results highlight the potential of BRT systems in improving traffic operations in over-crowded traffic corridors and the vital role of conflict treatments in achieving successful operations.

Review of road user mobility impacts and criteria for prioritising highway-rail grade crossings for grade separation

ABSTRACT Road users experience mobility impacts when a train occupies a highway-rail grade (level) crossing. Research has shown that the cost of reduced mobility exceeds safety costs, yet there is little consistency in the integration of mobility-related criteria into approaches for prioritising crossings for grade separation. A synthesis of findings from a review of literature and practice demonstrated the importance of mobility impacts at blocked crossings, identified and compared mobility-related decision criteria and actionable thresholds used within prioritisation approaches to rank crossings for grade separation, and revealed methods to quantify and monetise delay at blocked crossings. The review identified the need for the joint application of traffic microsimulation and intelligent transportation systems to quantify road user delay at blocked crossings. Such work should consider network-level effects, account for the severe consequences of delay for certain road users (e.g. emergency responders), and develop methods for monetising delay impacts associated with different road users. Moreover, a knowledge gap persists in establishing the interrelationship between road user delay at blocked crossings, risky behaviour, and safety impacts. Finally, further work is required to establish and calibrate thresholds for mobility-related criteria within prioritisation approaches used to rank crossings for all types of improvements, including grade separation.

GRADE SEPARATION: ITS EFFECT ON THE PUBLIC PERCEPTION OF THE URBAN LANDSCAPE. CASE STUDY: HAMEDAN, IRAN

Urbanization has brought about dramatic changes in the quality of the landscape in Hamedan, which is located in a mountainous area in the west of Iran. Not only these changes affect the people's well-being, but also how they perceive the new landscape. This paper aims to analyze the effects of newly built grade separations on the public perception of the urban landscape. In keeping with this aim, the survey was a suitable method to collect the people's opinions on the quality of the urban landscape. Unity, complexity, order, and aesthetics are the main factors that affect the quality of the urban landscape and its perception. The structural equation model of the research showed that unity through aesthetics is the critical path that affects the people's image of the city and their landscape preference. The results confirm that the public perception of the landscape quality, which is essential to planners, is affected by different kinds of intersection. Additionally, it specifies that the unique structure of Hamedan and its development in the last decades has a significant role in the people's landscape preferences and on their perception of it.

The Fatal Accident at Biodiversity Flyover in Hyderabad - A Case Study

Urban disasters, Traffic is unavoidable due to increase in density of vehicles without adding more road space to the city. This is demanding for more flyovers, grade separators to avoid congestion at the junctions. Hyderabad is congesting with many junctions adding up to the heavy traffic and waiting time, energy, fuel and polluting the city with noise and air pollution. For economic benefit and decongestion of major junctions, Flyovers were planned and constructed. To meet this demand in Gachibowli and Hi-Tech city area, a flyover was constructed by MVR Infra projects near biodiversity junction. The present paper describes the incident of fatal accident taken place on November 23, 2019. The study also reveals aftermath actions taken by the government of Telangana and suggested various sections in the Indian penal codes for such incidents.

Liquid–Liquid Phase Separation-Related Genes Associated with Tumor Grade and Prognosis in Hepatocellular Carcinoma: A Bioinformatic Study

AimThe aim of the present study was to identify the association between tumor grade and liquid–liquid phase separation (LLPS)-related genes, and to generate a LLPS-related gene-based risk index (LLPSRI) as a prognostic tool for hepatocellular carcinoma (HCC).MethodsWeighted gene correlation network analysis was performed to test whether the LLPS-related gene modules were associated with tumor grade of HCC. The candidate modules were subjected to functional enrichment analysis. We generated a LLPSRI using the expression profiles of the hub genes among the candidate modules in order to identify patients at high risk. Then, the biological characteristics of the high-risk patients were revealed using gene set enrichment analysis. Additionally, an independent external data set was used to validate the LLPSRI.ResultsFour gene modules showed a significant positive correlation with tumor grade and involved various cancer-related pathways. Among the hub genes, six were selected to generate the LLPSRI, which was significantly associated with prognosis of HCC patients. The LLPSRI could successfully divide patients with HCC into high- and low-risk groups, and patients in the high-risk group showed shorter overall survival than those in the low-risk group. E2F, MYC, and mTORC1 signaling may be important determinants of survival in the high-risk group. The prognostic value of the LLPSRI was validated with the independent external data set.ConclusionWe identified LLPS-related gene modules that are associated with HCC tumor grade. The LLPSRI may be useful as a prognostic marker of HCC, and it may reliably stratify patients into groups at low or high risk of worse survival. Our analysis also suggests that certain biological characteristics of HCC may be associated with high risk of worse survival.

Rail noise grade separation alternative analysis case study

The San Francisco Bay Area has an existing commuter rail system that brings commuters from southern regional communities into the downtown city center. One of the communities served by commuter rail service is the City of Palo Alto, CA, which includes four active grade crossings, each requiring train horn sounding for each train event. The City wished to evaluate various options to eliminate the noise generated from horn soundings by creating road/rail grade separations at each existing grade crossing and other possible noise and vibration control elements. The alternatives included crossing closures, rail bed trenching, viaducts, roadway underpasses, and tunnels. A noise and vibration study was undertaken to provide an analysis of which alternatives would provide better reductions in noise and vibration in the surrounding community. The study included an assessment of existing noise levels and predicted future noise and vibration levels for construction and operation of each proposed alternative using current established noise and vibration methodology. The results of this study included comparisons of the noise and vibration associated with each of the of the proposed alternatives that could be used in conjunction with other studies considering cost, traffic, safety, aesthetics and other factors to select an overall preferred alternative.

Experimental and numerical evaluation of the performances of type‐C and three‐segment demisters used in cooling towers

AbstractDemisters have become a key vapour‐liquid separation device for eliminating mist and preventing any escape of liquid droplets from cooling towers. In this paper, the overall performances of two types of demisters, namely type‐C and three‐segment demisters, are systematically investigated by using both experimental and numerical methods. The validation results show that the numerical results agree well with experimental data. On this basis, the underlying influences of key operating parameters, such as the circulating pressure of the pump, spray water flow rate, inlet gas velocity, and droplet size on the overall performance, are revealed. The results show that the overall separation efficiency is more sensitive to the gas velocity and increasing the gas velocity leads to two distinct declining stages of the overall separation efficiency for both demisters. The first stage appears due to the competition between the drag force and the inertial/centrifugal forces, while the next stage arises mainly due to the droplet re‐entrainment. The geometric design of the type‐C demister is more conducive to the separation of the fine droplets due to the presence of the hook plate, even at a relatively low gas velocity. Besides, the type‐C demister has more potential to reduce the power consumption while achieving a higher profit for a given grade separation efficiency.

Interchange Sight Distance and Design: Aspects and Implementation

The primary purpose of an interchange is to enable an appropriate level of access to the freeway in a safe and beneficial way to the driver. It improves road safety and traffic operation by reducing or eliminating traffic conflicts that would occur if grade separation were not provided (e.g. intersection). Crossing conflicts are eliminated and turning conflicts are either eliminated or minimized. The paper focuses on sight distance criteria in the geometric design of interchanges and junctions, specifically, implementation of stopping sight distance (SSD) and decision sight distance (DSD). These issues incorporate implementation of sight distance policy for: ramps’ geometric design, ramp terminals’ components, and basic lanes’ reduction. These sight distance criteria can alleviate safety by reducing conflicts and confusion to the driver and by keeping alignment simple, direct, and consistent. Specifically, DSD affects traffic control and intelligent transportation systems applications.

Multi-criteria prioritization of highway-rail grade crossings for improvements: a case study

ABSTRACT This paper presents a multi-criteria methodology for prioritizing highway-rail grade crossings for grade separation or other major improvements. The traditional approach for making grade-crossing investment decisions has been guided primarily by the Federal Highway Administration Railroad–Highway Grade Crossing Handbook, which focuses heavily on traffic and safety-related factors. However, it does not consider other criteria such as economic competitiveness, environmental sustainability, and livability. Due to factors including 1) increasing traffic demands resulting in significant delays at crossings, 2) the high cost of grade separation, 3) the long-lasting impact of grade separation on a community, and 4) funding requirements from grant applications, several factors should be considered in crossing selection. The main contributions of this paper are 1) a novel robust prioritization methodology that considers safety, economic, environmental, and community/livability. 2) a case study that prioritizes crossings at two separate rail corridors and a comparison of the results with the expert judgment. The case studies use data that is readily available to practitioners and implementation is fostered by the provision of an Excel Toolkit.

A Study on related side road in development process of railway grade separation

A Study on related side road in development process of railway grade separation

High Prevalence of Superior Labral Anterior-Posterior Tears Associated With Acute Acromioclavicular Joint Separation of All Injury Grades.

Background:Despite the relatively high number of cases of acromioclavicular joint (AC) separation in the athletic population, optimal clinical outcomes are not achieved in every case. Limited data exist regarding the prevalence of intra-articular glenohumeral pathologies (IAPs) associated with acute AC separation of all injury grades.Purpose:To determine the prevalence of IAPs associated with AC separation, regardless of severity.Study Design:Case series; Level of evidence, 4.Methods:A total of 62 patients (mean age, 37.6 years) with acute AC separation were included in this study; 41 were nonoverhead recreational athletes. All patients underwent magnetic resonance arthrography (MRA) to evaluate for IAPs. Arthroscopic data from patients undergoing surgical treatment were correlated with MRA results.Results:Patients sustained acute AC separation of Rockwood grade 1 (16.1%), grade 2 (46.8%), grade 3 (25.8%), and grade 4 (11.3%). A concomitant IAP was present in 48 of 62 (77.4%) patients and included superior labral anterior-posterior tears (72.6%), anterior labral tears (24.2%), posterior labral tears (4.8%), supraspinatus tears (3.2%), and inferior glenohumeral ligament ruptures (1.6%). There were 18 (29.0%) patients who had a concomitant pathology in >1 intra-articular structure (combined IAPs). Additionally, 71.8% of patients with grade 1 and 2 AC separation had associated IAPs, and 23.1% had combined IAPs. Furthermore, in patients younger than 40 years, 64.0% of those with grade 1 to 3 AC separation demonstrated associated labral pathologies. There was no difference when comparing age or severity of AC separation and the prevalence of concomitant labral tears (P = .36 and .22, respectively).Conclusion:There was a high prevalence of IAPs among patients undergoing MRA after AC separation. While an IAP has been described in association with high-grade AC separation previously, the high prevalence of IAPs in low-grade separation in our study was unexpected and suggests that a thorough evaluation and clinical follow-up for patients with all grades of AC separation may be beneficial.

Numerical investigation on the fluid droplet separation performance of corrugated plate gas-liquid separators

Separation and purification technology should be optimized, the performance of corrugated plate gas-liquid separators presently need to be geometrically improved for the low separation efficiency and high pressure cost. This paper mainly investigates the separation performance of corrugated plate gas-liquid separators with different vane types through 3D computational fluid dynamics (CFD).The velocity, pressure, and turbulence energy magnitude that are remarkably influenced by vanes’ type are compared, and friction factor (f) and separation efficiency (η) that are correlated to the vane type are numerically analyzed. The fluid film thickness and droplet diameter distribution are predicted, and the variations in pressure drop, grade separation efficiency, and overall separation efficiency are obtained to evaluate the performance of separators. And additionally, the correlations for the collection efficiency as a function of the Stokes number have been found, and the numerical data to those correlations have been fitted. It is found that the separator STV1 contributes mostly in enhancing the separation efficiency but with high pressure drop, and separators PV and SV have low pressure drop and separation efficiency. The separator MV is considered to have optimized performance for the 24.3 Pa and 97.6% under the airflow velocity U = 1.00 m/s, the separator can be used in a wider range of airflow velocity without losing the separation performance. This study can be used as a reference for the design of wave plate separator.

Socialising on a Skywalk: How Hong Kong's Elevated Walkways Become Public Open Spaces

In high-density Asian cities, the increasing scarcity of public open spaces gives rise to the need for stationary activities to tap into spaces originally conceived exclusively to channel pedestrian movements, such as grade separation pedestrian systems. However, the types and patterns of stationary activities on elevated walkways remain mostly unexplored. This study focuses on Hong Kong, wherein the scarcity of public open space characterises an extreme condition and where the burden of this scarcity falls most heavily on disadvantaged social groups, such as migrant workers. The findings highlight the prevalence of socially oriented activities and the importance of food as a gathering factor.

Optimizing the Traffic Operation System of 14th-Ramadhan Signalized Intersection in Baghdad City using HCS Technique

The purposes of the study are assessing the current level of service (LOS) at the 14th-Ramadhan signalized intersection in CBD area of Al-Mansoor district in Baghdad city and increasing the improvement of the traffic operation system by investigating appropriate proposals to increase the traffic capacity of this facility. Data of traffic flow collected using Tally mark method by many observers. Evaluation of the current intersection is to be taken in consideration using HCS Technique (2010), also existing and proposal layouts are displayed using AutoCAD (2017). The results showed that the selected traffic facility are currently suffered from serious lowering in service level causing forced conditions (LOS “F”). Thus, most important considerations should be considered for developing in the LOS by proposing many solutions. In summary, the study is proposed to execute the overpass structure (Grade Separation Bridge) along 14th-Ramadhan street from southbound to northbound directions and vice versa (two lanes in each direction) considering the third proposal (P3). By using HCS2010, the LOS will be changed from F to B assuming that it is expected to continue at higher traffic performance for approximately at least 15 year later

Numerical analysis of chevron demisters with drainage hooks in optimizing separation performance

Chevron demister is widely used in the industry program to remove the liquid droplets from gas flow. Design a demister with optimal separation performance (higher separation efficiency and lower pressure loss) is mainly concerned in the industry process. In this study, the separation performances of the four demisters (named as A, B, C, and D) are numerically evaluated and compared to find the ideal one. A combination of DPM, EWF model, and DRW model are used to simulate the motion of droplets in gas flow. Contours of velocity magnitude, pressure, particle tracks, and wall film thickness on vanes are obtained. Overall separation efficiency η, grade separation efficiency ηd and pressure loss ΔP are also discussed. It can be concluded that separation efficiency of type D is 17% higher than that of type A when inlet velocity v = 2 m/s, and becomes 3% higher when v = 10 m/s. Pressure loss increases 5178.2 Pa, 6278.2 Pa, 8621.1 Pa and 11,450.2 Pa for type A, B, C and D respectively when v increases from 2 m/s to 10 m/s. Large droplets are mainly captured at the first two stages, as the velocity increases, the liquid film expands backwards and can be observed at the last two stages. Compared to double hook, single hook induces higher separation efficiency as well as pressure loss. Splashing and film stripping are the main reason of re-entrainment. The ideal type of chevron demister is related to the specified situation with respect to its separation efficiency and pressure loss.

Construction schedule, an influential factor on air pollution in urban infrastructure projects

Urbanization growth and aging infrastructures necessitate new infrastructure construction projects in congested urban areas. Urban construction projects interrupt the regular on-road vehicle traffic flow that affects air pollution concentration in the adjacent areas. The project schedule, however, is a possible contributor to the air pollution which has been neglected to date. This research proposes a new framework to account for the impact of different urban project schedule alternatives on air pollution emission near the construction zones. The proposed framework uses the capabilities of vehicle traffic simulation to evaluate air pollution emission of different construction schedule alternatives and reduce the resulting emission in urban construction projects. The capability of the proposed framework is verified in a real grade separation case. Pollution concentration shows a potential reduction of up to 41% in sensitive locations. The achieved resulting values represent potential emission reduction of 7.8% for CO2, 8.2% for NOx, and 3.8% for PM10. The achieved results in the case study confirm the impact of the construction schedule on the air pollution emission throughout the project’s construction. It justifies the application of the framework in the congested urban areas. The proposed framework in the research contributes to the sustainable improvement of urban infrastructure projects.

Separating Poor Playmates: Untangling Commuter Rail from Freight

North American commuter railroads run their trains largely on tracks shared with freights (and in the northeastern US, often shared with intercity passenger trains). This sharing makes commuter rail relatively affordable to implement. However, as freight traffic grows, so does the potential for delays. If freight and commuter operations affect each other’s performance, it may be necessary to consider separation measures, not adding to the existing shared-track capacity. Temporal separation can work on low-volume operations. Busier lines may require physical separation, which can be implemented in several forms for trunk lines (grade separation at junctions, freight bypass, partial trunk line separation, and full trunk line separation), as well as physical separation in downtown areas. This article identifies these separation options, describes their attributes, presents representative examples, and outlines criteria for evaluation.

Control and traffic signal warrant assessment of intersection sites

Frequent evaluations are required to upgrade mobility and safety at intersections. This thus paper proposes a typical scenario to identify suitable controls for installing appropriate traffic signals.Five individual intersections were studied within the Babylon province, of Iraq, and graphical methods were used to identify suitable controls. Three graphs were adopted based on recommendations from the Institute of Highway Transportation (IHT), Department of Transportation (DoT) and the Iraqi Highway Design Manual (SORB). In addition, warrants for traffic signal installation according to the Manual Uniform Traffic Control Devices (MUTCD) regulations were checked with HCS 2010 software.According to IHT recommendations, three of the five intersections should be of a priority type and the others should take on a grade separation and a roundabout or a similar signal type. According to DoT, three of five intersections should be roundabouts and the rest Ghost Islands. The SORB recommends that all intersections should be controlled or altered to interchanges. Optimisation of suitable controls for each site should thus take all three methods into account in view of restrictions on area and budget. According to MUTCD, all of the intersections justify the installation of traffic signals, though further evaluation complementary to the proposed scenario would be useful.