Relative Capacity and Performance of Fixed- and Moving-Block Control Systems on North American Freight Railway Lines and Shared Passenger Corridors

Abstract

North American railroads are facing increasing demand for safe, efficient, and reliable freight and passenger transportation. The high cost of constructing additional track infrastructure to increase capacity and improve reliability provides railroads with a strong financial motivation to increase the productivity of their existing mainlines by reducing the headway between trains. The objective of this research is to assess potential for advanced Positive Train Control (PTC) systems with virtual and moving blocks to improve the capacity and performance of Class 1 railroad mainline corridors. Rail Traffic Controller software is used to simulate and compare the delay performance and capacity of train operations on a representative rail corridor under fixed wayside block signals and moving blocks. The experiment also investigates possible interactions between the capacity benefits of moving blocks and traffic volume, traffic composition, and amount of second main track. Moving blocks can increase the capacity of single-track corridors by several trains per day, serving as an effective substitute to construction of additional second main track infrastructure in the short term. Moving blocks are shown to have the greatest capacity benefit when the corridor has more second main track and traffic volumes are high. Compared with three-aspect signal systems, much of the benefits of moving blocks can be obtained from adding signals and implementing a four-aspect signal system. Knowledge of train delay performance and line capacity under moving blocks will aid railway practitioners in determining if the benefits of these systems justify the required incremental investment over current PTC overlay implementations.

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

“…The combination of more frequent sidings and moving blocks is more capable of handling traffic peaks caused by schedule flexibility. Generally, for the Even Freight traffic mix, the fixed block scenarios performed the same or worse than the moving blocks scenarios, building on previous findings that moving blocks allow for reduced train delay on existing infrastructure (9).…”

“…The dispatcher will strongly favor higher-priority trains in conflicts while tolerating greater delays for slower, lower-priority trains. This is likely the situation for the 4A 2 3 10 No Fleets scenarios which are expected to have the lowest line capacity (9). By introducing fleets and moving blocks to the network, the train meet process becomes more efficient with less delay incurred by the stopped train.…”

“…However, as currently implemented, PTC systems are primarily safety overlays on existing fixed block control systems with limited business benefits. Advanced PTC systems promise both to improve safety and to increase line capacity on existing track infrastructure, primarily by increasing the availability and accuracy of operational and train location information, and reducing the minimum separation required between trains ( 9 ).…”

Railway Capacity Enhancement with Modern Signalling Systems – A Literature Review

“…Meeting the target traffic volume under different configurations of signalling systems requires tuning the traffic mix with infrastructural characteristics. For the same level of capacity on a corridor with heterogeneous train operations, the moving block technology requires fewer double-track sections than three-aspect and four-aspect signalling systems, providing better resistance to train delays [44]. The capacitive advantages of the moving block are continuously growing with the increase in the amount of double-track railway sections but to the detriment of infrastructure savings.…”

Development of an imitation model of container transportation by railway area of Dostyk-Zhezqazghan-Iletsk

“…The diagram shows that the main share of TTCS is in relay-contact systems (72%) of the volume operated in the Republic of Kazakhstan. At the same time, there is a tendency for further development of systems [10] using the "moving block sections" technology [11,12]. The organization of this transport corridor is directly related to the further development of infrastructure, which includes railway automation and telemechanics systems, which is dictated by the need to increase the volume of container traffic.…”