A newly developed tool can predict 3D electromagnetic fields caused by rail electrification systems. This provides early knowledge of possible threats to nearby people, buildings, systems and facilities.
Electrical and magnetic fields are all around us. Natural events such as lightning storms emit them. The earth’s magnetic field, meanwhile, guides the migration of birds and, as the force that makes compasses point to the north, has steered ships and courageous explorers over centuries.
Today, electrical and magnetic fields are the basis for most of our day-to-day conveniences and utilities. They are fundamental in supplying power to our homes, enable our mobile phones to work, and let us watch our favourite TV shows. They also allow us to move quickly, for example, on electric railway systems.
However, the electromagnetic fields produced by currents flowing through railway cables and rails have a magnitude that can affect people’s health and the safety of systems and technological equipment. As such, they are a big concern for the design of rail electrification systems, especially if the rail infrastructure is close to residential areas and hospitals, such as urban transit systems, tramways or Light Rail Transit.
New technologies like regenerative braking — which converts the kinetic energy of a train slowing down into electrical energy that can be either used immediately or stored — can equally become a hazard, as the generated currents can be stronger than those related to acceleration.
Identifying and removing risk
A new tool developed by AECOM’s rail team in Madrid is able to ease these fears. Known as EMFRail, it can calculate the effects of the electromagnetic emissions caused by overhead electrification systems or electrical track equipment. It can also simulate solutions in early design stages in a realistic environment, before the construction of the line — a very useful feature as reconstructing and repairing infrastructure once completed is difficult and expensive.
The tool has been developed using MATLAB software and works by using several sources of information to calculate the effects of electric currents surrounding a rail line. These include line profile, substation positions, train characteristics, relative position and distances between different elements (such as cables, rails or overhead equipment), as well as train frequency and speed.
During a recent project, the tool calculated the magnetic field at a tram platform to analyse the health risk to people with heart pacemakers standing near the electrification equipment. It also assessed the intensity and effect of magnetic fields due to rail lines close to hospitals or research centres, which can disturb sensitive technology, such as magnetic resonance imaging (MRI) and electron microscope equipment.
In another, EMFRail estimated the level of exposure to people living nearby— information that can then be compared against the standard levels for human exposure as defined and quantified by the International Commission on Non-Ionizing Radiation Protection.
Electromagnetic compatibility aims at ensuring that different equipment operates correctly in a common electromagnetic environment. It is a big concern for the rail industry. By being able to predict the electromagnetic behaviour of a proposed section of rail infrastructure, EMFRail can anticipate problems and solve them before construction by testing mitigation options — a result that reduces risk, improves project efficiency and saves money.