Slotted Schedules for Corridors with Mixed Freight and Passenger Operations (2026)
Chapter: Introduction
TRANSIT COOPERATIVE RESEARCH PROGRAM
CONTENTS
Operational Design of Slotted Schedules
Recommended Changes to the TCQSM
Slotted Schedules for Corridors with Mixed Freight and Passenger Operations
As part of TCRP Project A-47, “Transit Capacity and Quality of Service Manual, Fourth Edition,” the research team conducted a series of small research tasks to develop new content for the manual. This TCRP research results digest (RRD) is one of 12 presenting the results of these research tasks. Slotted schedules, specific time–space slots defined for rail corridors where different classes of trains share the same tracks, provide operational flexibility and can minimize costly infrastructure expansion. This RRD documents current practice and describes how slotted schedules can be applied to expand commuter or other passenger rail service without compromising freight capacity or reliability. The responsible staff officer is Dianne Schwager. Links to the 12 RRDs and TCRP Web-Only Document 79: Developing the Fourth Edition of the Transit Capacity and Quality of Service Manual are available on the catalog page for TCRP Research Report 262: Transit Capacity and Quality of Service Manual, Fourth Edition (https://doi.org/10.17226/29449).
INTRODUCTION
The research team for this small research task explored the concept and application of slotted schedules in rail corridors where passenger and freight services share infrastructure. As transit agencies seek to expand service windows and improve bidirectional, all-day service, especially in the post-pandemic era of more dispersed travel demand, new planning and coordination approaches are needed. Slotted scheduling offers a potential framework for improving the efficiency, reliability, and transparency of shared operations.
Research Task Objective
The research teamʼs objective was to examine how slotted schedules can be used to guide service planning and infrastructure investment in U.S. rail corridors where passenger and freight trains operate on the same tracks. A slotted schedule is a planning and operational approach that defines specific time–space slots throughout the day for various classes of trains—typically categorized by speed, acceleration, stopping patterns, and service type—so that trains can operate without conflicts. Each slot represents a recurring, conflict-free path on a string-line diagram, allowing for reliable movement of both freight and passenger trains. String-line diagrams are the best way to visualize train slots, especially a series of scheduled train slots over the course of a day or a peak travel period, known as a slot catalog. A string-line diagram shows the movement of a train over time and distance along a rail corridor. Each actual train, or opportunity to run a train, is represented by a line on the diagram. The lines cross each other at locations where trains running in opposite directions pass each other (meets) or faster trains pass slower trains running in the same direction (overtakes). Meets and overtakes must occur in places where (a) a sufficient number of tracks are available, and (b) the available tracks are sufficiently long to accommodate train movements without conflicts or undue delays.
In the context of mixed-use corridors, especially those owned by freight railroads, slotted scheduling provides a way to plan for future service growth, preserve operational flexibility, and minimize costly
