At the Americana at Brand in Glendale, CA, the money saved on overhead wires could be spent on lavish appointments for the streetcars themselves. Photo Gomaco Trolley Company.

We tend to think of streetcars as operating on a fixed guideway.  The majority of the world’s streetcar systems, however, move between two of them, the unobtrusive rails in the ground and the power lines that run overhead and always in sight.  The streetcar movement is founded on simplicity and minimizing costs, on blending transit with existing and new neighborhoods. Negative impacts to utilities and street infrastructure are minimized, and projects are designed for ease of construction. Stops are simple, spaced relatively closely together in support of the streetcar’s role as a pedestrian accelerator.  Yet for all of this melding the catenaries remain, for some part of a majestic whole, for others simply blight.

Most streetcars operating in the U.S., whether vintage (original authentic vehicles), heritage (built to resemble

On most streetcar systems the wires are always overhead and in sight. Photo Quim Berenguer

original vehicles) or modern state-of-the-art vehicles, are powered by an electric overhead wire, also know as a trolley wire that carries between 600 and 750 volts of direct current (DC), versus alternating current (AC) most people are familiar with in their everyday lives. Examples of these three types of vehicles include the Pearly Thomas Company vintage streetcars used on the St. Charles line in New Orleans, the Birney replica streetcars produced by Gomaco Trolley Company for Tampa’s system, and the modern streetcar or European tram style vehicle built by Skoda for Portland.

To transfer the power from the wire to the vehicle, a spring loaded pole or a panagraph extends from the vehicle and makes contact with the trolley wire, a piece of bare copper approximately one-half inch in diameter. Although this power distribution system is much simpler than one typically associated with light rail systems, the cost off installing such a power distribution system is still significant as it also requires substations to convert commercial AC power to DC power and poles with mast arms to support the wire. Other considerations include the visual impact of the many poles and the spider web of wires needed to support and suspend the system, and the need to protect metal utilities from the corrosive effects of stray DC current associated with these types of systems. 

To avoid these impacts and reduce the cost of implementation, one well-establish system in Galveston and one recent new start in Savannah have chosen to use streetcars with an onboard electric generator powered by either a diesel or gasoline engine similar to current hybrid cars. Alternative wireless solutions are rapidly gaining attention. Two battery-powered-vehicle systems are operating in California: at The Grove in Los Angeles and the Americana at Brand in Glendale. Both of these complexes are large shopping, dining, and entertainment destinations. Streetcar and light rail vehicle suppliers around the world, similar to bus and automobile companies are exploring alternative ways to power their vehicles and reduce environmental impacts and visual blight.

Three categories of alternative technologies are either in operation, research and development or the testing phase: wayside, on-board energy storage, and on-board power source technologies.

Wayside technologies require external infrastructure to provide power to the vehicle. The one wayside example currently in use is a surface-mounted contact rail—a third rail, if you will— which utilizes a rail between the running rails that is energized only when the vehicle is above it; the remainder of the time there is no power to the rail.  This system requires a significant wayside investment in addition to the cost of the on-board vehicle technology and is only in revenue service in Bordeaux, France for a short segment in an historic district.

Within the on-board energy storage technology category, there are three types of devices: batteries, ultra capacitors and flywheels.  In addition to the two examples in the U.S., two historic districts in Nice, France are using battery technology. This system is combined with an overhead wire for the remainder of the line and the batteries are charged from the overhead wire.  This system has been in revenue service since November of 2007. Kawasaki also has a similar technology under development and in demonstration in Japan.  In the U.S., the Gomaco Trolley Company received a contract in August 2009 from a client in Kingston, New York to supply a vintage streetcar purchased from Melbourne, Australia using its battery technology.  Two other U.S. cities, St. Louis and Rock Hill, South Carolina are also considering this technology for use in replica Birney vehicles similar to those built for Tampa and Little Rock. Similar to the system in Nice, the system proposed for St. Louis will use a combination of battery and overhead wire segments. Rock Hill is still in the planning stage and could choose to go with just a battery or a combination similar to St. Louis.

Ultra capacitors are another form of on-board device capable of storing energy generated during braking. This device is not intended for use as an off-wire power source, but it has been demonstrated off-wire for a distance of approximately 0.3 miles. There are several suppliers and a four-year trial has been completed in Mannheim, Germany.  Flywheels, similar to ultra capacitors, store energy generated during breaking.  This technology is not in revenue service, but is in demonstration in Rotterdam, Netherlands and has operated off-wire for approximately one mile.

In the on-board power source category, there are only two systems in use: fuel cells and fuel/electric hybrids. Fuel cells charge batteries, which drive electric motors.  This technology is still in research and development, and currently only being demonstrated with buses at Alameda County Transit in Oakland.  Fuel/electric hybrids utilize a diesel engine attached to a generator that powers electric motors.  There are a number of examples of these types of vehicles in revenue service including the Galveston and Savannah systems.

So, if you want a streetcar, but you are not sure you want or can afford an overhead power distribution system, there are a number of alternative technologies being evaluated and demonstrated. However, current proven options are generally limited to on-board storage and on-board power source technologies or a combination of the two. Another key factor is supplier interest. Before suppliers will make the investment in research and development, they have to feel there is a large enough market for the technology. With the high level of interest in alternative energy sources and green technology, wireless may be the future of rail technology.

Steven Carroll is  a Vice President of Rail Transit for HDR, Inc. with over 32 years of experience planning, engineering, construction, and operation of rail freight and rail transit projects.  HDR is a multidisciplinary planning and engineering firm with over 8,000 employee-owners and 158 offices in the U.S. and Canada.  HDR is a recognized leader in the field of streetcar planning and engineering and has led or supported over two dozen streetcar projects in recent years.

This article first appeared in the Fall 2009 Streetcar Issue of Trip Planner Magazine.