In science, critical mass identifies the point where the presence of sufficient materials or energy makes a process self-sustaining.
Rail transit system starts of every kind are underway from coast to coast and North to South. Add to that most of the systems 12 or more years old are expanding their network or at least adding rolling stock to increase the frequency and passenger capacity of services.
Rail transit is no longer simply the domain of a small number of advocates crying in the wilderness. Cities and their citizens are now demanding rail transit — even if the funds are not always there to build and sustain a system.
One of the initial difficulties in selling the concept of rail transit to many metropolitan areas in the mid- to late-20th century was that so few Americans had any kind of contact with rail transit. Yes, some travelers had visited cities in Europe or elsewhere in the world that had a diverse and highly integrated transit network that included a variety of rail operations, but many administrators, from the local to federal level were not quite sure how some of these concepts would translate to the U.S. environment. Want to show your city council members or county commissioners a successful rail transit operation? Where would you take them without spending huge amounts of money?
However, slowly a growing number of cities and regions managed to act on the courage of their convictions or the urgings of transit advocates and implemented rail.
In 1981 San Diego led the way by opening its first line from the city center to San Ysidro at the Mexican border with a new generation of light rail vehicles.
By the end of the 20th century, all the major metropolitan areas of California, home of the American automobile culture, embraced a variety of rail transit options. California was now seen as an example of what could be done with rail transit.
Pace-setter San Diego also found the solution to converting existing rail corridors to light rail without cutting off service to rail freight customers — time separation. U.S. federal regulations prohibit mixing freight traffic with a light rail operation, though such operations have operated successfully in Europe for many years. San Diego’s operation compromised by permitting switching of freight customers in the late-night hours after the transit operation had shut down. That type of operation was also applied when the San Diego system opened its second line to El Cajon in the hills above the city.
This year test operations are already underway on a partial segment of the Charlotte Lynx South Corridor light rail line, with revenue operation planned for November. The Lynx light rail, part of the Charlotte Area Transit System (CATS), is the first modern light rail system for the Carolinas, though a heritage trolley operation had helped lay the groundwork on part of the 9.6-mile South Corridor initial line. The heritage trolley operation will return after construction is completed for the Lynx system, sharing tracks on part of the line during off-peak periods.
At the same time, Charlotte is moving forward with plans for a commuter rail operation from downtown to Mooresville to the north on an existing Norfolk Southern freight line with excess train capacity.
The light rail line (then nearing completion, but not yet open to the public) will be a major showpiece when the American Public Transportation Assciation (APTA) holds its annual meeting in Charlotte in October. After touring Charlotte’s Lynx light rail line, many of the transit officials and municipal representatives will undoubtedly leave the city with a case of rail transit envy.
That, in part, illustrates the maturity of rail transit in the United States Transit planners now have a better understanding of which rail mode or combination of rail modes may make sense in a given corridor and what the economic trade-offs between each mode are.