Capacity of Single-Track Railway Lines with Short Sidings to Support Operation of Long Freight Trains

Atanassov, I.; Dick, C. Tyler

doi:10.3141/2475-12

Cited by 7 publications

(5 citation statements)

References 6 publications

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“…The technical approach of this study extends the examination of over-length trains previously conducted by the authors. 18,19 While the underlying simulation framework parallels the previous work, methodological advances are made by consideration of multiple combinations of train lengths to vary the “train length ratio,” and through consideration of train-type delays in addition to average train delay.…”

Section: Methodsmentioning

confidence: 99%

“…To contrast against the bidirectional scenarios where the same number of long trains operates in each direction, an additional set of “unidirectional” simulations were conducted with all long trains operating in the same direction. The goal of these additional simulations was to investigate if the particular efficiencies afforded by directional operation of over-length trains identified by the author's earlier work 18,19 (namely elimination of meets between two long trains) alter the distribution of train delay between short and long trains.…”

Section: Methodsmentioning

confidence: 99%

“…Previous work conducted by the authors concluded that the introduction of over-length trains on a route without any extended passing sidings greatly increased average train delay. 18,19 For the combination of “short” 100-car trains and “long” 150-car trains, only one half of the passing sidings on a representative mainline need to be lengthened to mitigate the delay increase from the over-length trains.…”

Section: Introductionmentioning

confidence: 99%

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Relative train length and the infrastructure required to mitigate delays from operating combinations of normal and over-length freight trains on single-track railway lines in North America

Dick

Atanassov

Kippen

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part F:

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Distributed power locomotives have facilitated longer heavy-haul freight trains that improve the efficiency of railway operations. In North America, where the majority of mainlines are single track, the potential operational and economic advantages of long trains are limited by the inadequate length of many existing passing sidings (passing loops). To alleviate the challenge of operating trains that exceed the length of passing sidings, railways preserve the mainline capacity by extending passing sidings. However, industry practitioners rarely optimize the extent of infrastructure investment for the volume of over-length train traffic on a particular route. This paper investigates how different combinations of normal and over-length trains, and their relative lengths, relate to the number of siding extensions necessary to mitigate the delay performance of over-length train operation on a single-track rail corridor. The experiments used Rail Traffic Controller simulation software to determine train delay for various combinations of short and long train lengths under different directional distributions of a given daily railcar throughput volume. Simulation results suggest a relationship between the ratio of train lengths and the infrastructure expansion required to eliminate the delay introduced by operating over-length trains on the initial route. Over-length trains exhibit delay benefits from siding extensions while short trains are relatively insensitive to the expanded infrastructure. Assigning directional preference to over-length trains improves the overall average long-train delay at the expense of delay to short trains. These results will allow railway practitioners to make more informed decisions on the optimal incremental capital expansion strategy for the operation of over-length trains.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relative train length and the infrastructure required to mitigate delays from operating combinations of normal and over-length freight trains on single-track railway lines in North America

Dick

Atanassov

Kippen

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…To improve operational flexibility, certain railroads have also installed double-length “super sidings” with mid-siding crossovers that are ideal for meeting two-train fleets ( 16 ). Although there are many practical, engineering, environmental and physical constraints that may prevent a particular siding from being extended to accommodate fleets, previous research on operation of over-length trains that exceed the length of passing sidings suggests that fleets can be operated efficiently while only extending a fraction of the passing sidings along a corridor ( 17 , 18 ).…”

Section: Train Fleetsmentioning

confidence: 99%

Improving Railway Operational Efficiency with Moving Blocks, Train Fleeting, and Alternative Single-Track Configurations

Rivera

Evans

2020

Transportation Research Record: Journal of the Transportation R

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With installation of positive train control (PTC) on many U.S. rail corridors, Class I railroads may soon leverage these investments in communications network infrastructure to implement “advanced PTC” systems incorporating moving blocks. Train control with moving blocks can benefit operating strategies that dispatch fleets of multiple trains running at minimum headways. On single-track corridors with passing sidings long enough to hold multiple trains, fleeting may increase the efficiency of train meets, reduce train delay, and yield incremental capacity benefits. Alternative single-track configurations with fleet-length sidings at double the spacing of conventional single-train sidings can facilitate these operating strategies while minimizing additional track infrastructure and associated capital and maintenance costs. To investigate the operational synergies between moving blocks, fleeting, and longer but less frequent sidings, Rail Traffic Controller software is used to simulate and compare the delay performance of train operations on representative rail corridors for different combinations of fleeting strategy, train control system, siding configuration, and freight traffic composition. Operating fleets in conjunction with moving blocks produces the lowest overall train delay in specific cases of low schedule flexibility and heterogeneous traffic. With more efficient meets, moving blocks and/or fleeting primarily benefit low priority trains that typically wait for opposing traffic during train meets. Such incremental line capacity benefits have short-term financial consequences as they allow additional capital investments in double track to be deferred. Knowledge of train delay performance under moving blocks and fleeting will aid railway practitioners evaluating investments in advanced PTC systems and track infrastructure expansion.

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“…However, long trains spend more time traversing speed restrictions and impose higher individual meet delays on opposing traffic ( 7 ). Long trains can also increase mainline train delay and reduce capacity if they exceed the length of most passing sidings on single-track lines ( 8 , 9 ), a key consideration in North America where approximately 70 percent of principal mainlines are single track with passing sidings ( 10 ). At yards, long trains with a greater number of blocks are more complicated to assemble and prepare for departure, decreasing yard efficiency ( 11 ).…”

mentioning

confidence: 99%

Quantifying Recent Trends in Class 1 Freight Railroad Train Length and Weight by Train Type

Dick

Zhao

Liu

et al. 2021

Transportation Research Record: Journal of the Transportation R

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Railroads have a strong economic incentive to maximize the length and weight of freight trains. Since the mid-1990s, various technological innovations have facilitated operation of longer and heavier trains, and railroads have made infrastructure investments to accommodate them. Recent shifts in railway operating and management strategies have placed added emphasis on long trains but have also drawn public and agency scrutiny. The advantages and disadvantages of increased train size are difficult to analyze because public data on train length and weight over time are limited. Articulated intermodal railcars, artificially short local trains, and light empty unit trains skew industry averages across all train types and mask trends over time. To provide greater insight on the average and distribution of train length and weight for different train types over time, the research team conducted a detailed analysis of Class 1 railroad annual report financial data and Surface Transportation Board waybill sample data collected for the years 1996 through 2018. Dividing traffic statistics by train type allows for a specific focus on loaded unit train length and weight distributions that isolates many factors skewing overall averages. Over the past 23 years, the average length and weight of loaded non-hazmat unit trains have steadily increased. Train size distributions indicate that unit trains exceeding 140 railcars in length have become more frequent over the past 10 years, whereas hazmat unit trains are typically smaller in size. This information can aid researchers and industry practitioners in assessing the benefits and disadvantages of operating longer trains.

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Capacity of Single-Track Railway Lines with Short Sidings to Support Operation of Long Freight Trains

Cited by 7 publications

References 6 publications

Relative train length and the infrastructure required to mitigate delays from operating combinations of normal and over-length freight trains on single-track railway lines in North America

Relative train length and the infrastructure required to mitigate delays from operating combinations of normal and over-length freight trains on single-track railway lines in North America

Improving Railway Operational Efficiency with Moving Blocks, Train Fleeting, and Alternative Single-Track Configurations

Quantifying Recent Trends in Class 1 Freight Railroad Train Length and Weight by Train Type

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