Operating costs for metro services have sky-rocketed in recent decades. This is in part due to the cost of maintaining good service on a system with declining ridership and in part due to a failure to take advantage of known methods of cost control. Some of the techniques proposed below can be applied to existing systems; others can only be built into new systems.
Track Maintenance
Track maintenance costs can be reduced by several techniques:
- Adopt Modern Construction. The use of continuous welded rail on concrete ties and the provision of good drainage can reduce maintenance costs. Maintenance-related outages are less frequent, the track does not deteriorate so quickly, and a smoother ride is provided.
- Prevent Wheel slip. Wheel slip occurs whenever the motorman applies too much power and the wheels start to slip (overspeed). Computer control can eliminate this problem, which causes premature rail wear.
- Minimize Curvature. Curved track wears far faster than straight, and the sharper the curve the worse the problem.
- Reduce Ton-mileage. Track wear is directly correlated to traffic and weight. Reducing vehicle weights helps.
Energy Efficiency
Most modern rapid transit vehicles are surprisingly wasteful of energy. Most electric rail vehicles use dynamic braking - the motors are used to slow the train, with the energy dissipated to heating grids atop the cars (which leads to even hotter tunnels in the summer). This saves brake wear but does not recover any of the energy used to accelerate the train, which, in metro service with frequent stops, is the largest component of energy usage. Full regenerative braking can recover most of the energy otherwise lost to braking. In addition, most vehicles are heavier than need be. New designs and advanced materials should permit significant weight reductions.
Wheel Truing
In all rail operations, wheel sets are routinely removed from the vehicle and turned on a lathe to restore roundness and the correct profile. This is a very expensive operation, and after wheels have been turned several times they must be discarded or reworked. There are several causes for wheels going out of true:
- Emergency stops. These can be nearly eliminated on a grade-separated right-of-way. With computer control of motors, faster, non-sliding stops can be achieved than by simply locking up the wheels.
- Sharp curves. Curves are the bane of all railroading. In a city designed around its transport system, curves can be kept gentle, greatly reducing wear of the wheel profile.
- Disc brakes. There is no longer any excuse for building passenger rail vehicles with service brakes that run on the wheels. This practice is dangerous (leading to wheel failure if a brake drags) and very expensive in operation. The entire problem can be avoided simply by using regenerative braking, which can provide smooth stops without wear. (With advanced computerized motor controllers it is possible to stop a train without use of the brakes.)
Reducing Personnel Costs
Fully grade-separateed systems can run without drivers. While it took nearly three decades to perfect the technology, several systems are now operating routinely in fully-automated mode. Two other approaches also reduce labor costs.
- High Speed and Capacity. The higher the average speed of the vehicle and the greater the number of seats behind the driver, the lower the per-seat-mile personnel operating costs. City buses are terrible in this respect. Even articulated buses have only 80 seats behind the driver, and average speeds are very low due to traffic and slow loading and unloading up and down steps.
- Tight Route Network. A compact route network with frequent service saves money and serves riders better. Sparse networks with the necessarily infrequent service are expensive to operate and provide slow service. A concentration of origins and destinations is a necessary requirement of a compact route network; the suburban pattern of habitation makes such a network impossible.
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