Wind-Induced Tip Over

An operational safety issue facing railroad operators is wind-induced tip-over. A study was completed using CFD to develop a database of tip-over tendencies for a variety of car types within the Norfolk Southern fleet. The use of this database in the development of a speed restricting system for the Sandusky Bay Bridge is also discussed.

Train Accident

Freight Train Derailment: 18 February 2006
Montreal, Quebec, Kahnawake Bridge
67 miles/hour crosswinds

High winds have caused a number of other accidents involving freight trains:

  • 28 January 1987: Union Pacific Railroad,
    4 empty containers blown from two TTWX cars near Laramie, Wyoming (wind speeds reached 45 mph)
  • 24 March 1987: Union Pacific Railroad,
    25 cars derailed near Brule, Nebraska (up to 53 mph winds)
  • 11 November 1998: Consolidated Rail Corporation,
    64 Road Railer intermodal cars derailed on Sandusky Bay Causeway in Ohio
  • 11 February 2003: Norfolk Southern Railway,
    train derailed on Sandusky Bay Causeway in Ohio
  • 01 November 1999: Canadian Pacific Railway,
    2 empty double-stacked containers derailed near Poplar Point, Manitoba during high crosswinds (107 km/h)
  • 17 June 2013: Burlington Northern Santa Fe Railway,
    71 rail cars that were double-stacked with shipping containers derailed near Hereford, Texas
  • 18 September 2013: Union Pacific Railroad,
    7 cars derailed near Chicago, Illinois


Airflow Science's work includes:

Rail Car
  • Develop database of railcar rolling moment to predict impending tip-over conditions. Analysis included box cars, hopper cars, well cars, gondola cars, autorack, 53' trailer/flat cars.
    • Wind tunnel test data of CFD simulations
  • Supply relations to integrate aerodynamic database into a vehicle dynamics modeler's VAMPIRE simulations.
  • Develop real-time computer algorithm to alert train dispatch center of appropriate speed reductions in possible tip-over conditions.
  • Select and locate wind sensor and configure system to display appropriate speed restrictions.


Tipping Moment Data:

Wind Tunnel Graph

Wind Tunnel Tests
(16% and 30% Scale)

CFD of Train Car Tipping
CFD Legend

CFD Models (Example is 53 Foot Well Car)


Results of Study:

A Speed Restricting System was developed which is installed alongside the tracks at the Sandusky Bridge. The system measures real-time wind conditions and communicates with dispatchers to provide immediate recommendations for safe speeds based on wind speed and direction for multiple car types.

Speed Limit

Allowed Train Speed Chart

Speed Restricting

Speed Restricting System (SRS) Screenshot

Azore CFD Software