Heavy-rail lines have an exclusive right-of-way that does not intersect streets or pedestrian ways, so trains can go faster and be longer without obstructing other traffic. Most are elevated or in subways, traveling at ground level for only brief periods of time as they transition between subway and elevated.
Subways and elevateds have existed in Boston, Chicago, New York, and Philadelphia since before 1900. In the 1970s, several cities tried to build new heavy-rail systems, including Atlanta, Baltimore, Miami, San Francisco, and Washington. All of them cost far more than originally projected and attracted fewer riders than projected. Ridership on the Baltimore and Miami lines was particularly poor and these cities stopped building heavy rail. Even cities whose heavy-rail lines are often considered successful, such as Atlanta and Washington, had overruns of 60 to 80 percent and ridership shortfalls of 25 to 50 percent.
While heavy-rail capacities are much higher than light rail, the costs are also much greater. Six heavy-rail lines proposed for funding in the FTA’s 2015 budget cost an average of $441 million per mile. The least expensive line is $230 million per mile in San Jose, while the most expensive is $2.2 billion per mile in Manhattan.
The average heavy-rail car in service in 2012 had 53 seats and room for about 100 more people standing. In actual service, these cars carried an average of 27.5 people. According to the American Public Transportation Association, the average speed of heavy rail in 2012 was 20.0 miles per hour.
Recently, a new phenomenon has emerged that is a sort of cross between light and heavy rail. This consists of rail lines with an exclusive right of way, but station platforms that are too short to run long trains. The result is a hybrid that combines the high costs of heavy rail with the low capacities of light rail.
Seattle has built and is building such a high-cost, low-capacity rail line and calls it light rail. The University Link line that is currently under construction costs $628 million per mile yet its capacity will be no greater than an ordinary light-rail line. Honolulu is spending more than $260 million per mile–and cost overruns will push this above $300 million–on an elevated line that it calls heavy rail. However, the platforms and trains will be so short that its capacity will be little better than light rail.
While a transit line that combines the cost-disadvantage of heavy rail with the capacity-disadvantage of light rail may seem dumb, for contractors it is ideal. When the line is completed, it will be more likely filled to near capacity during rush hour than a true high-capacity line. This will allow proponents to argue that the line is a great success and even more should be built.