How do roller coasters work?

Dear Cecil: We recently passed the 100th anniversary of the roller coaster (but you undoubtedly knew that). The first one, called the “Switchback Railway,” was built by LaMarcus Adna Thompson at Coney Island (and you know that, too.) Obviously I’m a buff, but an unread one. So please explain: how does a roller coaster work, aside from the fact that they go up and then come down? What keeps them on the track? How can they run several trains simultaneously? How safe are they these days? And finally, which coaster is the biggest, and which the fastest? Great America, Magic Mountain, and King’s Island all claim to be the pinnacle of achievement in certain areas — which is the true winner? Lisa O., Chicago

Cecil replies:

Not to get persnickety about it, kumquat, but 1984 was the centennial of the first custom-built American roller coaster, not the first roller coaster period. The first one opened in Paris in 1804. The first U.S. roller coaster (of sorts) started operation in 1870 on a converted mountain railway in Mauch Chunk — great name, huh? — Pennsylvania. However, let’s not sweat the details. Here’s a rundown on your basic roller coaster technology: (1) Motive power. A chain drags you up, gravity gets you down. I assume you do not need this explained in further detail. (2) Wheels. Three sets clamp the cars onto the rails from above (the road wheels), the side (the guide wheels), and below (the upstop wheels). The idea here was worked out in 1912. (3) Ratchets. OK, you’re in the roller coaster being hauled up the first hill by the chain, when suddenly the chain breaks. So you roll back down and make liver sausage out of two dozen cute little tykes in the train behind you, right? Wrong. Ratchets on the track (they’re what makes that characteristic clicking noise as you go uphill) keep the train from rolling backward. Modern roller coasters often have ratchets or some other antibacksliding device on other hills down the line as well. (4) Brakes. At key points along the route there are track brakes, which essentially grabe the train and either slow it down (for instance, when it’s pulling into a station) or, if necessary, stop it altogether. (5) Signals. The train rolls over a sensing device that sends a signal to RC Central Command. In the old days this consisted of some mope with a couple levers; nowadays it’s more likely a computer. Say you’ve got a roller coaster with two trains on it. You put a sensing device and a track brake at the midpoint on the route. When Train A passes the midpoint, it signals that it’s OK to send out Train B. Now suppose Train A gets stuck somewhere short of the station. No sweat — you use the track brake to stop Train B at the midpoint.

In the old days this system did not always work. In 1937 a train on the Pippin (later the Silver Flash) roller coaster at Chicago’s late, lamented Riverview Park somehow stopped on the tracks and was subsequently rammed by another train, injuring 60-70 people (no deaths). Nowadays, roller coaster buffs say, technological advances have made such a disaster as inconceivable as … oh, an accident at Three Mile Island. On some computer-operated systems you can run as many as five trains at once. If anything goes wrong, the computer stops all the trains automatically.

Actually, most roller coaster accidents are the result of determined applications of stupidity on the part of riders. But occasionally there are other problems. Cecil has heard tell of one accident on a roller coaster in California in which attendants were unable to get the restraining bar locked around one very fat woman rider, so they evidently let her go up without it. She was thrown out of the car and killed.

Government regulation of roller coasters and amusement parks in general for a long time was quite lax, despite their poor safety record. In May of of 1984, for instance (I don’t know if this was a typical month), nine people were killed and 34 injured on amusement park rides nationwide. In June of 1986, three people were killed and 15 others were injured when the last car of a triple-loop roller coaster went off the tracks and crashed into a concrete pillar in a crowded indoor shopping center in Edmonton, Alberta. Lately some states have begun to enact more stringent inspection requirements, and the U.S. Consumer Products Safety Commission is authorized to inspect rides in states that do not have inspection programs.

The fastest roller coaster in the world is the American Eagle at Great America in Gurnee, Illinois, with a claimed top speed of 66.21 MPH. Tallest is the 193-foot-high Tojoko Land Loop Coaster in Hyogo, Japan. Longest is the Beast at King’s Island near Cincinnati, Ohio (7,400 feet). As for the best — well, I talked to Robert Cartmell, the leading expert on roller coasters (no kidding — last time I talked to him, this guy had ridden 341 of these babies around the world). His top three are: #1 — Texas Cyclone, Astroworld, Houston; #2 — Mister Twister, Elitch’s Gardens, Denver; and #3 — Riverside Cyclone, Riverside Park, Agawam, Massachusetts.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.