Train control systems use a Safe Braking Distance (SBD) to determine the appropriate length to separate trains to avoid collisions. The same properties that allow trains to propel themselves with great efficiency also prevent them from stopping suddenly. Once the SBD is determined, it can be applied to the signal system design by creating “signal blocks” that are used to determine the location of signal equipment along the track. In its simplest form, each signal block provides sufficient distance to stop the train traveling at the maximum authorized speed. More advanced train control systems utilize other means of train detection such as global positioning satellites, or track mounted transponders. Regardless of the train control technology used, the methods of determining SBD remain the same. Positive Train Control (PTC) type systems are being developed for deployment throughout the United States and are required on all passenger lines, including High Speed Rail. However all of these methodologies are based on traditional worst case scenarios. With PTC required to be deployed before the 2015 time limit, freight carriers are working on new braking algorithms that involve specific inputs such as speed, train weight and alignment. This is called “Adaptive Braking” in that it calculates a different solution based on the data on hand [22]. Reports on this development detail purely reactive methodology. Reactive methods simply imply that conditions for the calculation are based on information that is in or before real time. It is proposed to utilize a proactive approach in determining SBD to monitor adhesion conditions in advance of the train to optimize SBD and capacity.

This content is only available via PDF.
You do not currently have access to this content.