10-Year FTA Low-Speed Urban Maglev Research Program Shows Technology is Feasible, But Infrastructure Costs and Availability of Technologies Are “Intimidating”
|Vehicle chassis of one of the UML research projects (General Atomics). Click to enlarge.|
A 10-year US program to develop low-speed urban magnetic levitation (UML) technology has demonstrated that such systems are feasible to consider as alternatives in the US, but that the initial infrastructure costs and availability of safety and operationally certified maglev technologies are “intimidating”, according to a assessment report prepared by Science Applications International Corporation (SAIC) and sponsored by the Federal Transit Administration (FTA).
Maglev—a transportation technology in which trains are supported by magnetic forces without any wheels contacting rail surfaces—promises several attractive benefits including the ability to operate in challenging terrain with steep grades, tight turns, all-weather operation, low maintenance, rapid acceleration, quiet operation, and superior ride quality, among others. For urban alignments, maglev potentially could eliminate the need for tunnels and noise abatement, resulting in significant cost savings.
However, the results of multiple projects sponsored as part of the program indicated that substantial up-front costs exist. Most large urban areas in the United States have already invested in some type of mass transit system (subway or light rail) and urban maglev poses a fundamental change in technology that is viewed as being both a major risk and cost-prohibitive by transit agencies and investors, according to the report.
While maglev trains are in use throughout the world, those systems are primarily high-speed test environment systems where speeds reach in excess of 250 miles per hour. Low-speed urban maglev faces a much different set of operating circumstances than high-speed magnetic levitation systems, and the successful introduction of such a system to an urban environment presents different challenges, according to the report. Some of the challenges faced by urban maglev include:
Slower speeds, due to the short distances between stops. Urban maglev should require a maximum speed of about 100 mph.
Obtaining rights of way in an urban area will be very challenging.
US safety standards are in many instances much more demanding than standards in other countries. Adapting a foreign system to run in the United States will require careful scrutiny of all safety requirements to determine if it is economically feasible to actually adapt the system.
In 1999, the FTA initiated the Low-Speed Urban Magnetic Levitation (UML) Program to develop magnetic levitation technology that offers a cost effective, reliable, and environmentally sound transit option for urban mass transportation in the United States.
The basic functions of maglev technology include:
Levitation or suspension of the transit vehicle from the guideway. The two principal means of levitation are electromagnetic suspension (EMS) and electrodynamic suspension (EDS).
EMS is an attractive force levitation system whereby electromagnets on the vehicle interact with and are attracted to magnetic-attractive components on the guideway. EMS is made especially practical by continuing advances in electronic control systems that precisely maintain the air gap between vehicle and guideway, preventing contact and optimizing power usage. An attractive feature of EDS, according to the report, is its inherent ability to compensate for variations in payload weight, dynamic loads, and guideway irregularities through rapid changes in the magnetic field (via the control system) resulting in the maintenance of the proper vehicle-guideway air gaps.Electrodynamic suspension (EDS) employs magnets on the moving vehicle to induce currents in the guideway. A key technical property of EDS is that the repulsive forces produced are inherently stable because the magnetic repulsion increases as the vehicle-guideway gap decreases. Usually the vehicle must be equipped with wheels or other forms of support for takeoff and landing because an EDS levitation design will not operate at speeds below approximately 20 mph. EDS performance has progressed with advances in materials research, cryogenics, and the potential application of superconducting magnet technology.
Forward or reverse propulsion. Two types of propulsions systems are employed using magnetic technologies. Both rely on the principle of stator motor design and magnetic induction to create propulsive physical forces. Long-stator propulsion uses an electrically powered linear motor winding in the guideway; short-stator propulsion uses a linear induction motor (LIM) winding onboard the vehicle and a passive guideway with a magnetically receptive material (e.g., ferromagnetic aluminum, copper, etc.) installed along the rail surface. The LIM is heavy and reduces vehicle payload capacity, typically resulting in higher operating costs and lower revenue potential compared to the long-stator propulsion. However, the guideway costs are less.
Vehicle guidance. Guidance systems are required in all degrees of freedom in order to steer or guide the vehicle safely along the guideway under all operating speeds and conditions. The guidance system can be the result of direct application of the magnetic forces necessary to meet ride requirements and can be used in either an attractive or repulsive manner. Similarly, certain design concepts allow for the same magnets on board the vehicle which supply levitation to be used concurrently for guidance. This approach is more complicated, but if successful can reduce vehicle weight.
FTA funded five projects under the UML program:
The General Atomics Urban Maglev Project (General Atomics, San Diego, CA as the lead company) to develop a system based on permanent magnets.
Maglev 2000 of Florida Corporation to establish the feasibility of a superconducting electrodynamics suspension (repulsive force) technology.
The Colorado Department of Transportation partnered with Sandia National Laboratories, Colorado Intermountain Fixed Guideway Authority, and Maglev Technology Group, LLC to develop of a low-speed maglev to link Denver International airport with Vail, about 140 miles away.
Maglev Urban System Associates of Baltimore, MD to explore the viability of bringing to the United States a Japanese-developed low-speed maglev technology that has undergone more than 100,000 kilometers of testing.
MagneMotion, Inc. to lead the development of a key Maglev technology for implementation in transportation systems serving traffic-congested urban areas. A principal element of the MagneMotion urban maglev system is the use of the company’s linear synchronous motor technology to propel bus-sized vehicles that can operate with short headway under automatic control.
All of these teams focused on four main areas: systems studies; base technology development; route-specific requirements; and a preliminary design for a full-scale system concept.
The principal lesson learned from the perspective of the overall project execution was that, as with most research efforts, there will be unexpected challenges and obstacles during the course of the projects. Each project team identified different challenges, such as gaining cooperation with State, city, and local stakeholders for alignment issues; obtaining details on already operating systems that were not considered proprietary; and underestimating the technical challenges of super cooling magnets.
In addition, while the very nature of this research program draws creative individuals who are interested in solving complex problems, but very often are not as concerned about following sound project management principles, let alone Federal guidelines for submitting required reports on time. The lesson learned from the program in this regard was the value of requiring someone on the project team to provide a project plan with enough detail that FTA could determine when the project had drifted and enough detailed updates to determine whether progress has been achieved.—FTA Low-Speed Urban Maglev Research Program Lessons Learned