Analyzing railroad congestion in a dense urban network through the use of a road traffic network fundamental diagram concept

Document Type

Journal Article

Publication Date


Subject Area

place - europe, place - urban, mode - rail, mode - mass transit, operations - scheduling, operations - capacity, planning - service quality, planning - service improvement, policy - congestion, infrastructure - station, infrastructure - traffic signals


Railroad, Mass transit, Congestion, Line fundamental diagram


Transilien, the SNCF branch in charge of operating the main urban railroad network in the area of Paris, faces a regular increase of passenger flows. The planning of railway operations is made carefully through simulation runs which help to assess the timetable stability. However, many disturbances appear and cause train delays. Due to the nature of the railroad network those delays are cumulative and an on-line update of the timetable is not always successful in maintaining the trains schedules. In this tensed context, operators are searching solutions to enhance the use of the infrastructure capacity and achieve a better service quality. A needed step towards this objective is a better understanding of the phenomena of disruptions, in particular because the expansion of congestion is so far not clearly understood. This paper explores the possibility to transpose a traffic flow theory tool, the network fundamental diagram, in the field of dense railroad traffic. Railroad traffic is different from road traffic in many ways: railways are a planned system, traffic volume does not satisfy the continuum hypothesis, stations force stops and the signalization system brings a discrete behavior. Despite those big differences we show how to build a similar tool for a railroad system, the Line Fundamental Diagram (LFD), and how to interpret some obtained shapes for those diagrams. These diagrams give us some means to compare plan and reality. We also identify the limits that have to be overcome to take benefits of the road traffic tools in railroad traffic analysis.


Permission to publish the abstract has been given by SpringerLink, copyright remains with them.