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A View from the Window – the Locomotive Windshield

While defogging and chipping ice off of automobile windshields can be slow, tedious work, motorists typically have the tools and the ability to pull over to complete the task. For operators of locomotives pulling freight cars, the task is a bit more daunting. Locomotives are designed to operate in very harsh weather conditions in order to minimize delays
associated with inclement weather. Manufacturers have stringent performance specifications regarding the defogging equipment integrated into the windshields they
WTI Researcher prepares the “inside” of the windshield before activating the defrosting mechanism. “Outside” of the locomotive windshield, frozen to -40 degrees in the
MSU Subzero Science and Engineering Research Facility.
install on their locomotives. To facilitate meeting this standard, the Western Transportation Institute (WTI) has been contracted to test the defogging performance of a windshield, utilizing the Subzero Science and Engineering Research Facility at Montana State University.
WTI designed and constructed a frame to hold the locomotive windshield with its rubber seal at a 60 degree angle from horizontal to simulate the actual position of a locomotive windshield. Both sides of the windshield will be exposed to the same ambient air temperature; however, the “inside” will be shielded from the wind. The “outside” of the windshield will face a fan assembly capable of simulating a maximum wind speed of approximately 30 miles per hour. A 10 mm thick layer of ice will be frozen to the “outside” of the windshield glass by creating a water dam around the edge of the glass and filling the surface with water while the windshield is positioned horizontally, then reducing the temperature of the environmental chamber to below-freezing temperatures. Once the water is frozen, the windshield will be mounted in the test frame and the temperature in the cold chamber will be reduced to -40°F. Once the chamber reaches this temperature, the defogger will be switched on. A video camera will be used to monitor the visibility of the windshield and record the amount of time it takes to achieve clear conditions. The window must be clear of ice within 60 seconds to meet the industry performance standard.
Opened in 2008, the MSU SubZero lab is a unique and state-of-the-art suite of laboratories used to study the effects of cold temperatures on projects across many scientific disciplines. It is an ideal setting to replicate the very cold and harsh environments in which the windshields will operate. Jason Harwood, Research Associate for WTI, designed and constructed the frame and will conduct the freezing and defogging testing. “The parameters that we are testing have much to do with the safety of operating the new locomotives,” says Harwood. “This testing process is significant to locomotive manufacturers because it verifies that subcontractors have met specific requirements for various components of the locomotive.” At the end of the project, the manufacturer will be provided with a report showing the defogging rate and overall performance of the windshield in the extreme conditions.