The National Transportation Safety Board (NTSB) has issued a Safety Alert that focuses on the visibility of railroad signals.

On railroads, light-emitting diode (LED) railroad signals may mask nearby incandescent signals, preventing incandescent signals from being visible to train crews. If LED and incandescent signals are installed in close proximity to one another, the LED signal may appear brighter or closer, causing crews to confuse the sequence of the signals as they approach. This effect may be more pronounced the closer the train gets to the signals.

A Safety Alert is a brief information sheet that pinpoints a particular safety hazard and offers practical remedies to address the issue. This Alert highlights actions to avoid accidents by identifying locations where the close spacing of signals may cause a signal to either mask or visually dominate another signal, especially at locations where LED and incandescent light units have been installed in close proximity. These actions include evaluating the railroad computer aided dispatching software to prevent confusion when lining routes non-sequentially at multiple control points; conducting a hazard analysis that includes testing signal visibility with input from train crews; and through the use of configuration management.

The Safety Alert is available http://www.ntsb.gov/safety/safety-alerts/Documents/SA_038.pdf.

All 35 Safety Alerts the NTSB has issued are available at: http://www.ntsb.gov/safety/safety-alerts/Pages/default.aspx.