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Centralized Interlocking for Moving Block Research Project

Document Series
Technical Reports
Federal Railroad Administration
Report Number
Subject Positive Train Control
Centralized interlocking, CIXL, Quasi-Moving Block, QMB, Full Moving Block, FMB, Interoperable Train Control, ITC, Positive Train Control, PTC, Communications-Based Train Control, CBTC, train control

Transportation Technology Center, Inc. (TTCI) researched and developed concepts for a centralized interlocking (CIXL) system to satisfy the needs of North American railroads. The system leverages the Quasi-Moving Block (QMB) train control method; and provides maintainability and availability benefits. The proposed CIXL system is based on Positive Train Control (PTC) Exclusive Authorities (PTCEAs) that grant movement authority to trains and contain core interlocking data. Within the project, TTCI prepared a technology survey about existing CIXL systems, developed a concept of operations (ConOps) and performed a feasibility assessment for the proposed system.

Last updated: Tuesday, May 3, 2022