The quest to concoct a workable rubber-tired replacement for steel-wheel light rail transit (LRT)—on standard steel rails—seems eternal. Several variants of running a “tram on tires,” typically with some configuration of a center guiderail, have been developed.
Such systems have been installed in a handful of cities such as Nancy, Caen, Padua, Tianjin, Shanghai, and a few others—with very limited success. (The Caen version, plagued with reliability problems, is scheduled for conversion to standard steel-rail LRT by 2019.)
Despite such technological experiments, nothing so far has emerged to decisively substitute for bona fide LRT. Even despite a slowdown in U.S. LRT startups (mainly a result of the Federal Transit Administration freezing new rail starts not already approved for funding), LRT expansion has been booming worldwide.
Nevertheless, hopeful inventors keep trying—the latest iteration being an offering from China. In early June, railway rolling stock manufacturer CRRC debuted a “wireless” and “trackless light rail” system for the city of Zhuzhou rolling on supposedly “virtual rails”. The new line is slated to stretch 6.5 km (about four miles).
You can watch a short promotional video on YouTube:
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Actually, like previous iterations, the Zhuzhou “trackless train” is merely an elaboration of bus technology, involving an electrically powered, multi-articulated bus designed to resemble an LRT car. Sensors enable the bus to follow dashed lines painted in the roadway (although promotional photos and videos also show a driver with a steering wheel).
Periodically recharged lithium-ion batteries provide power. The bus is rated at a maximum speed of 70 km/hr (about 42 mph), and designers claim it can travel 25 km (about 15 miles) after a ten-minute charge.
In reality, there’s nothing particularly new about any of this technology. Multi-articulated buses have been operating in a small handful of cities (e.g., Curitiba) for decades. Battery power with recharging stations is an emerging propulsion technology now being deployed not just for buses but also for several new streetcar-tramway-style LRT projects, such as Oklahoma City’s new streetcar.
Optical guidance involving pavement striping has also been around for a while, albeit with less than stellar performance. It’s been tried and abandoned in several systems, including Las Vegas’s “MAX” BRT.
The length of the Zhuzhou three-unit articulated bus is just over 100 feet, and promoters claim it can carry up to 307 passengers. How comfortable that would be, even with air-conditioning, is dubious. (Exaggeration of effective carrying capacity by transit rolling stock vendors is commonplace.)
One of the designers’ nominal goals is to speed up public transportation development in major cities. But the emphasis of their promotional argumentation seems competitive—focusing on supposed advantages over steel-rail transit technology. Its developers assert a measly $2 million per kilometer capital investment cost for their invention (about $3.2 million per mile). So could this really become a replacement for true LRT?
In evaluating this technological LRT “replacement,” it’s first important to realize that installation costs of new “gadget” technologies are commonly lowballed by vendors. An investment of $3.2 million per mile would barely cover the cost of rolling stock, much less right-of-way, civil works, trackway (or a paveway), a signal and communications system, power, stations, and maintenance facilities. Especially in today’s cultural environment of “alternative facts” and rampant bombast, lowball cost claims need lots of scrutiny … and skepticism.
How would capital costs actually compare? As already noted above, LRT systems can be designed to operate free of an overhead contact system (OCS), just like the Zhuzhou bus.
However, the relative merits and costs of “wire-free” power vs. OCS have yet to be fully evaluated. While OCS can be eliminated, a power system is still needed to supply the recharging facilities. Propulsion batteries would also need to be replaced periodically, adding to long-term cost. Operational factors, such as particularly heavy passenger loads with A/C, or very steep grades, may require the higher power delivery of OCS. (The challenge of steep grades on future routes was a key factor in Cincinnati’s decision to install OCS for their new streetcar starter line.)
The Chinese promoters claim the “trackless” system could run on ordinary streets with other traffic, and seem to presume zero cost of right-of-way. But even in a mixed-use street lane, experience suggests reinforced pavement construction typically would be necessary to handle the considerably heavier rolling stock and intensive roadway wear-and-tear.
In reality, the trend both in China and the U.S. is to segregate transit in exclusive lanes—thus, a dedicated paveway for buses and track lanes for LRT. A fair comparison of investments would consider the full lifecycle costs of reinforced pavement vs. steel trackage.
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