Modeling the NAJPTC network using NS-2

Positive Train Control (PTC) refers to microprocessor-based communication technologies that are capable of preventing train collisions, derailments, and injuries to workers operating within the railroad system. In North America, there are 11 competing PTC projects in various stages of refinement. The North American Joint Positive Train Control Project (NAJPTC) is one of those efforts, based on the Advanced Train Control System (ATCS) protocol. NAJPTC is a joint development project of the Association of American Railroads, the Federal Railroad Administration, and the Illinois Department of Transportation. In this paper, we use a network simulation system (NS-2) to model NAJPTC ATCS communications to determine the feasibility of that PTC system when overlaid onto geographic data from Google Earth, and digital elevation data from the United States Geological Survey. Our simulations were useful in observing and tracking the signal strength of a moving train, resolving packet collisions via strategic base station placement, and modeling and mitigating communication losses.