Editor's Window31 May, 2005 By: Sara Ferris
Off track: Amtrak brake problem illustrates pitfalls of complex supply chain.
The recent brake woes oF Amtrak's Acela high-speed train exemplify the complexities of today's supply chains and the magnitude of the task PLM (product lifecycle management) products are trying to accomplish. It wasn't merely a case of neglected or delayed maintenance that forced Amtrak to pull all 20 Acela trains out of service until this summer. It was ultimately a communications problem, according to Fred E. Weiderhold Jr., the railroad's inspector general, in testimony before a U.S. House of Representatives subcommitte.
The Acela trains are manufactured by a consortium of Bombardier Transportation of Canada and Alstom of France. The subcontractor that manufactures the brake discs, a European company called SAB-Wabco, sent them along to another subcontractor, Knorr-Bremse of Germany. SAB-Wabco included a 66-page book, labeled 2 700 S-N, which specified inspections every 20,000 kilometers, or 12,400 miles. For its brake assembly, Knorr produced a shorter service bulletin that listed maintenance procedures but left out instructions for inspecting the spokes that connect the brake disc to the hub. Instead, it referred users to the SAB-Wabco 2 700 S-N for additional information.
Once one spoke cracked, Wiederhold said, the others were more likely to crack as well. To add to the mess, the subcontractor that maintains the Acela wheel sets reported the cracks to a subcontractor involved in making the brakes, but that report never made it to Amtrak. The end result was that by the time the problem was discovered, cracks had developed in 317 of the Acela fleet's 1,440 brake rotors.
Though we don't know whether PLM was used in this case, it's not clear whether a PLM product could have done much to avoid it. The process in place did retain and control the relevant product data. The error was in how the data was presented—in particular, the decision not to include the inspection information in the top-level service bulletin. Decisions like that are made at all stages of a project. As Weiderhold noted, "You can't give the guy on the shop floor all the technical manuals; the pile would be as tall as you or me."
A PLM system can collect data and make it available, in the hopes that more data will lead to better decisions. But ultimately, all final decisions still fall to the people designing and building the product. Every decision is a good one when it's made, at least to the person who's making it. It's only through hindsight that the bad ones become evident. Some applications hope to capture the decision-making process so that, when someone down the road asks, "What were you thinking?", you can look it up. Someday we'll no doubt see programs designed to automate good judgment and common sense.
Interestingly, decisions made early on in the Acela program conspired to make it more difficult to respond to the brake spoke problem. The train features a unique design that combined existing and new technologies, so the manufacturer had only about 80 replacement brakes in stock. A tight timetable and delays in production also led to an abbreviated testing period—about 35,000 miles, as compared with 165,000 miles for a new electric locomotive introduced in the early 1980s.