Field Testing Plan for Positive Train Control Enforcement in Passenger Terminals

In the United States, a train moving onto a terminating track at a passenger terminal relies on the train engineer’s operation. Currently, there are no mechanisms installed at the U.S. passenger terminals that are able to automatically stop a train before reaching the end of the track if an engineer fails to do so. The engineer’s actions determine whether the train will safely stop before the end of the terminating track. Thus, incapacitated or inattentive engineer operation would result in end-of-track collisions, such as the New Jersey Transit train accident at Hoboken Terminal in 2016. Currently, PTC enforcement is not required in passenger terminals. In an ongoing project tasked by the Federal Railroad Administration, we study the cost-effectiveness and operational impact of possible PTC enforcement to prevent end-of-track collisions. Specifically, a Concept of Operations (ConOps) was developed to outline the proposed plans to implement two of the most widely used PTC types, namely the Advanced Civil Speed Enforcement System (ACSES) and Interoperable Electronic Train Management System (I-ETMS). This paper describes in-field testing of the ConOps in ACSES-type terminal. In the planned field test, a train equipped with one locomotive and at least one passenger coach would be tested on platform tracks in a selected passenger terminal. These are three major testing components, which are test equipment, test track, and recorded information for each test sequence. Firstly, in terms of equipment, a traffic cone will be placed on the track to simulate a bumping post. In ACSES system, two sets of transponders are programmed to require a positive stop within a specified distance and mounted to the cross ties at specified positions. Secondly, a yard track will be used to test the feasibility of this exercise at the beginning. Upon successfully completing the test multiple times, a series of tests will also be made on the studied platform track. Thirdly, each test run should record the distance from the head end of the test train and the traffic cone for each test run. In addition, ACSES system should also record the information on the ACSES display as it passes the first and second transponder set, respectively. Overall, the field tests presented in this paper, along with previous work in benefit-cost analysis and operational impact assessment, can contribute to an assessment of the proposed PTC implementation at stub-end terminals in the United States in order to effectively and efficiently prevent end-of-track collisions.

Optimization of the Shunting Operation Plan at Electric Multiple Units Depots

The number of standard electric multiple units (EMUs) in China has increased from 1003 in 2013 to 3256 in 2018. For maintaining all EMUs in time, the high-speed rail system with the fast-developing number of EMUs is facing growing pressure. The maintenance and cleaning capacity of an EMU depot can be improved by a better shunting operation planning (SOP). This paper considers an SOP problem at EMU depots, which may have two types of yards, namely, stub-end and through. Every track at an EMU depot has two sections and can accommodate two short standard EMUs of 8 railcars or one long EMU of 16 railcars. As the SOP is currently handled manually by dispatchers, this paper proposes two integer linear programming models for two types of yards for daily planning and dispatching, which aim at minimizing the total delay time of all EMUs during the planning horizon. A Reduced Variable Neighborhood Search (RVNS) algorithm is designed to improve the solution efficiency. The results of the numerical experiment show that the RVNS algorithm can yield an optimal maintenance plan in a few seconds for depots of different layout types and can be applied to a computer-aided planning system. The track utilization rate of the maintenance yard with the stub-end type is higher than that of the through type. The stub-end type may be more suitable for the current schedule, as its total track utilization rate is much lower than the through type.

Thermomechanical Evaluation of the Performance and Integrity of a HDPE Stub-End Bolted Flange Connection

In this study, the integrity of a manhole structure made of a 78 in. high density polyethylene (HDPE) stub-end, steel ring, and blind flange, sealed with a compressed nonasbestos fiber (CNAF) gasket is investigated by means of a parametric finite element analysis (FEA). A coupled thermomechanical nonlinear FEA model is built, comprising of a heat transfer and a structural model, which allows modeling the complex thermal and mechanical loads and their interactions present during the operation of the manhole. The temperature-dependent elastic–plastic HDPE material constitutive behavior and the temperature-dependent nonlinear response of the CNAF gasket are accounted for in the model. Factors influencing the performance and integrity of the manhole such as stud-bolt pretorque level (Tb), internal pressure (Pi), and outer temperature (To) are considered. Based on the results, the integrity and performance of the structure are assessed in view of a leakage through the gasket criterion and a yielding of the HDPE stub-end criterion. The FEA results reveal that both Tb, Pi, and To significantly influence the performance (i.e., leakage) of the gasket and the integrity (i.e., yielding) of the HDPE stub-end. At 40 °C, it is possible to find a safe operational window for a range of Tb and Pi values, where no leakage through the gasket or yielding of the stub-end occurs. However, as the temperature is increased this safe operational window decreases considerably, and at 80 °C safe operation cannot be guaranteed where leakage, yielding, or both simultaneously, will lead to loss in performance and integrity of the manhole structure.

Prevention of End-of-Track Collisions at Passenger Terminals via Positive Train Control

A series of end-of-track collisions occurred in passenger terminals because of noncompliant actions from disengaged or inattentive engineers, resulting in significant property damage and casualties. Compared with other types of accidents, end-of-track collision has received much less attention in the prior research. To narrow this knowledge gap, this paper firstly analyzes the safety statistics of end-of-track collisions, then develops a fault tree analysis to understand the causes and contributing factors of end-of-track collisions. With the objective of mitigating this type of risk, this paper discusses the potential implementation of Positive Train Control (PTC) for the passenger terminal. This paper primarily focuses on the enforcement of the two most widely implemented systems, the Advanced Civil Speed Enforcement System (ACSES) and the Interoperable Electronic Train Management System (I-ETMS). For each implementation scenario, the Concept of Operations (ConOps) is proposed that depicts high-level system characteristics for the proposed PTC system enforcement at stub-end terminals. Ongoing work is being carried out by the authors to fully evaluate the cost-effectiveness and operational impacts of enforcing PTC in terminating tracks to prevent end-of-track collisions.

Pull-Out Performance of T-Stub End Plate Connected To Concrete Filled Thin-Walled Steel Tube (CFTST) using Lindapter Hollo-Bolts

The application of concrete filled steel tubes (CFSTs) as composite members has widely been used around the world and is becoming popular day by day for structural application especially in earthquake regions. This paper indicates that an experimental study was conducted to comprehend the behaviour of T-stub end plates connected to concrete filled thin-walled steel tube (CFTST) with different types of bolts and are subjected to pullout load. The bolts used are normal type bolt M20 grade 8.8 and Lindapter Hollo-bolt HB16 and HB20. A series of 10 mm thick T-stub end plates were fastened to 2 mm CFTST of 200 mm x 200 mm in cross-section. All of the specimens were subjected to monotonic pull-out load until failure. Based on test results, the Lidapter Hollo-bolts showed better performance compare to normal bolts. The highest ultimate limit load for T-stub end plate fasten with Lindapter Hollo-bolt is four times higher than with normal bolt although all end plates show similar behaviour and failure mode patterns. It can be concluded that T-stub end plate with Lindapter Hollo-bolt shows a better performance in the service limit and ultimate limit states according to the regulations in the design codes.

Pull-out performance of T-stub end plate connected to concrete filled thin-walled steel tube (CFTST) using lindapter hollo-bolts

The application of concrete filled steel tubes (CFSTs) as composite members has widely been used around the world and is becoming popular day by day for structural application especially in earthquake regions. This paper indicates that an experimental study was conducted to comprehend the behaviour of T-stub end plates connected to concrete filled thin-walled steel tube (CFTST) with different types of bolts and are subjected to pullout load. The bolts used are normal type bolt M20 grade 8.8 and Lindapter Hollo-bolt HB16 and HB20. A series of 10 mm thick T-stub end plates were fastened to 2 mm CFTST of 200 mm x 200 mm in cross-section. All of the specimens were subjected to monotonic pull-out load until failure. Based on test results, the Lidapter Hollo-bolts showed better performance compare to normal bolts. The highest ultimate limit load for T-stub end plate fasten with Lindapter Hollo-bolt is four times higher than with normal bolt although all end plates show similar behaviour and failure mode patterns. It can be concluded that T-stub end plate with Lindapter Hollo-bolt shows a better performance in the service limit and ultimate limit states according to the regulations in the design codes.

Pull-Out Performance of T-Stub End Plate Connected To Concrete Filled Thin-Walled Steel Tube (CFTST) using Lindapter Hollo-Bolts

The application of concrete filled steel tubes (CFSTs) as composite members has widely been used around the world and is becoming popular day by day for structural application especially in earthquake regions. This paper indicates that an experimental study was conducted to comprehend the behaviour of T-stub end plates connected to concrete filled thin-walled steel tube (CFTST) with different types of bolts and are subjected to pull-out load. The bolts used are normal type bolt M20 grade 8.8 and Lindapter Hollo-bolt HB16 and HB20. A series of 10 mm thick T-stub end plates were fastened to 2 mm CFTST of 200 mm x 200 mm in cross-section. All of the specimens were subjected to monotonic pull-out load until failure. Based on test results, the Lidapter Hollo-bolts showed better performance compare to normal bolts. The highest ultimate limit load for T-stub end plate fasten with Lindapter Hollo-bolt is four times higher than with normal bolt although all end plates show similar behaviour and failure mode patterns. It can be concluded that T-stub end plate with Lindapter Hollo-bolt shows a better performance in the service limit and ultimate limit states according to the regulations in the design codes.