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Using model-based software tools, engineers can develop the logic embedded in trains and on tracks to control train movement on the track. Image: ANSYS

High-speed rail is a frequently discussed topic, but one that has yet to become a reality in the U.S. A number of states and regions in the U.S. including Texas, California, the Pacific Northwest and Minnesota, to name a few, have planned projects to bring high-speed rail to fruition.

With an influx of interest and planning dedicated to high-speed rail, the safety of such systems has been called into question. Due to the unfortunate accidents in France, Spain and Switzerland, future passengers and project managers are concerned now more than ever about safety measures being taken into account. The discussions center around the systems used in trains and how they work or in worst case scenario fail to protect passengers as they travel at high speeds from one location to another.

Within the U.S., high speed rail travel is developing a high profile
The general view is that high-speed rail is easier to control because of the simple, straight shot routes taken. That being said, there are three basic issues that must be considered to form a foundation of safety; speed, avoiding other trains on the track and making sure that the train travels as intended. To address these complex mechanical factors, sophisticated software systems in both the train control center and on-board the train, can control these functions.

Automated safety at high speed
These automated safety systems have a strong track record in the aerospace industry and work well when properly implemented. For example, train control systems with sensors on the track and train can govern the speed of the train and its movement authority. Just like an autopilot on a plane, the over speed protection won’t allow the train operator to exceed the designated speed for that portion of the track.

Of course, systems and software can only be relied on to an extent. The terrible accident at Angrois, Santiago de Compostela in Spain occurred on a part of the track that didn’t have the automated systems for over speed protection in place, allowing for human error to occur. The train's data recorder showed that it was traveling at about twice the posted speed limit of 80 km/hr (50 mph) when it entered a bend in the line.

To ensure complete passenger safety, full automation—and as a result, full compliance to safety protocols—is vital. By minimizing potential human errors, operators are able to improve the safety of rail systems and for high-speed routes, which is of utmost importance. In the wake of the Angrois incident, the Spanish rail authority Adif installed three balises—track-mounted programmable transponders which communicate with the on-board computers and can cause an automatic brake application if speed restrictions are not obeyed.

High-speed railway. Image: ANSYSSafety from the ground up
The U.S. has the benefit of integrating this level of research into the early stage of design as high-speed rail projects are in their infancy. This ensures maximum safety for the plethora of rail projects in development. However, with the opportunity to instill best practices from the early stages of the project, this means that designers need to look at the software that governs the safety critical systems.

The effectiveness of that software, in terms of its safety, is defined by how well it answers the specific safety concerns of a given route. About 80% of the software issues in rail safety systems are caused by a misunderstanding of the requirements and specifications for the system in development. The failure in many complex systems is that the mission and the specification of the systems are not fully understood in a detailed fashion by engineers before they begin to code.

These complex systems need to be correct by construction. By using model-based techniques to remove the ambiguity of requirements and specifications, to verify the detailed design against those requirements and ensure it’s correctly implemented, safety begins to be implicit.

And finally, to remove the possibility of human error, the tools that automate the coding must be compliant with international safety specifications.

Of course there are areas for improvement. As high-speed rail starts to become a reality in the U.S., there are a few things to consider that will make riding the rails at 200 mph a bit safer. A structured, overarching safety standard is one. At present, the international rail industry currently doesn’t have one global standard that must be adhered to.

Despite Japan, France and Germany leading the world in high-speed rail travel, standards vary from country to country in Europe and Asia. If one standard for development of rail systems and software was available, requirements would be less complex with no variants. In this area, rail could take a page from the aerospace industry, where all commercial planes and helicopters must adhere and be certified under the same, demanding international standard. The European Rail Traffic Management (ERTMS) system is a good sign of progress here. It’s an initiative backed by the European Union to enhance cross-border interoperability and the procurement of signaling equipment by creating a single Europe-wide standard for train control and command systems. The ERTMS level 2 system is particularly well suited for high-speed passenger rail.

However, in application as well as development, it remains the case that automation is key. If an entire train is automated, safety is vastly improved. By deploying the latest generation of automated train control techniques, the ride is as safe as possible. From a business perspective, this level of automation also improves efficiency and energy use.

To ensure an impressive safety record, automation and comprehensively designed safety systems that can account for and override human error are vital for the future and safety of high-speed rail.