They are expensive. They are dangerous. They are unsightly.
They are the catenary lines used to power light-rail trains in the United States and Europe, and both manufacturers and rail lines have been seeking to do away with them for years. Fortunately, several companies have made advances that may make that possible. Test systems have been installed in Bordeaux, France, and Augsburg, Germany, already with promising results. The introduction of these new, catenary-less technologies may indeed mean overhead wires will be a thing of the past for the mass transit industry.
The Case Against Catenary Lines
A traditional catenary system carries a number of challenges for rail lines — both those already in existence and those proposed. Cost, safety, maintenance and aesthetics are all concerns whenever light rail is discussed, particularly for U.S. cities proposing creating light rail. While the environmental benefits of electrically powered trams make a strong argument for local governments wishing to find innovative solutions to their public transportation issues, the baggage of overhead power lines often sinks proposals before they can be implemented.
In addition to laying track, a catenary system requires miles and miles of electrical lines to be strung. That also requires poles, breaks, tensioning systems and all the peripheral equipment associated with creating a catenary system.
Accorder to Rainer Hombach of Kinkisharyo, manufacturer of the e-Brid power system and ameriTRAM light rail vehicles, “Some estimates show $7 to $7.5 million per mile for double track installation.” And that’s not all.
“This includes many hidden costs beyond just the obvious wire, poles and substations,” Hombach adds. “There are significant costs involved in property acquisition, utility feeds, duct banks and cathodic protection that are often overlooked when estimating the total cost of electrification.”
Cities considering light rails therefore aren’t just looking at the cost of purchasing trains and the tracks they run on.
Moreover, overhead lines require a lot of maintenance given the direct contact of the pantographs and their constant exposure to weather. This too makes cost an issue.
“Conventional systems are very sensitive to particular atmospheric conditions, particularly heavy storms and tornados,” notes Vito Siciliano of Ansaldo STS, whose TramWave system is designed to eliminate this problem. “The related maintenance and repair costs and service unavailability can become a major issue.”
“Winter storms play havoc with overhead wire systems,” he says. “Ice accumulation can cause ‘arcing,’ which damages the pantographs and can even go as far as to cause ‘snags,’ which rip the pantograph off the roof of the car or pull down the wire. It is not uncommon for operators to schedule non-revenue ‘ice runs’ ahead of normal service just to clear the catenary system of dangerous accumulations of ice and snow. Weather-related non-revenue runs are costly, complicate service schedules and are not an efficient use of the revenue fleet.”
And, of course, it doesn’t take a winter storm or a tornado to cause damage to a catenary line. Loose wires in the summer and wire breaks in the winter as a result of lines contracting and expanding with the temperature also create maintenance headaches.
A catenary line is a live wire suspended in the air. Weather issues therefore become serious safety concerns. Tornadoes and high winds can bring them down, which then puts a live current on the ground, exposing anyone nearby to danger of electrocution. Heavy snows or ice storms also have the potential to wreak this kind of havoc.
And the danger isn’t limited to innocent passersby. Maintenance and emergency crews must also put themselves at risk to work on the lines and repair them, especially if a storm brings a line down. In the event of a fire near a line, ladders must often be raised near and above power lines, putting emergency workers at risk.