The inefficiencies inherent in the frequent-stopping, constantly accelerating and braking operation of at grade rail systems place significant demands on sources of electrical power, as well as, the equipment and component parts of the systems’ vehicles. The cost of electrical power is determined by suppliers, transportation system operators have little control over expenditures for the energy that powers their facilities and vehicles. The design of AT Grade Rail vehicles and their electrical systems does not permit operators to reduce energy consumption to any significant degree.
Although AT Grade Rail is often referred to as “Light Rail”, this term is related only to the ridership capacity of the system. At Grade Rail vehicles are among the heaviest and most massive of land transportation vehicles. Much of this massiveness has evolved from old railroad technology and the rest of it results from efforts to improve the reliability of the system and the safety issues related to potential derailments and collisions with other vehicles. In the past, there has been no motivation for lighter weight or more efficient vehicles as there has been for aircraft and automobiles.
At grade rail systems make reasonably efficient use of electrical power relative to other transportation systems such as automobiles and airplanes. The generally heavier weight vehicles in service on at grade systems require significantly more electrical power than do even subways and inter-city trains.
At grade rail system designers and planners should be aware of tendencies for manufacturers to produce unnecessarily heavy or oversized rolling stock for use on at grade rail systems; thereby losing the advantages of lighter rail equipment and vehicles in the consumption of electrical energy.
The original technology for At Grade Rail vehicles was during a period when energy was a small expense. It is important to consider that the cost of electrical power, as well as other forms of power in use today, is expected to continue rising and may become the most significant operational cost of any mass transit system.