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Overshadowed by the congressional hearings into the Toyota runaway car issue, the US National Transportation Safety Board (NTSB) began the first of three days of hearings yesterday on the the June 2009 DC Metrocrash that killed nine and injured scores more.

Testimony by Metro's assistant chief engineer disclosed that there were at least two previous instances of "failures of the automatic train protection system" before the crash, said a story in today's Washington Post.

The Metro engineer said that in 2005 and in early 2009 Metro trains had come close to colliding. Equipment had been replaced after the 2005 incident, but he said that neither Metro nor the manufacturer of the equipment is "absolutely convinced" that the source of the problem in the automatic safety system was identified.

Up until this time, Metro officials had said that these two incidents and the train crash last year were unrelated.

The testimony also highlighted the numerous safety problems that have plagued Metro, especially over the past couple of years. It is clear that safety, while publicly portrayed as an important priority, is not treated as one.

The Post article, for instance, said that NTSB hearing Chairman Robert Sumwalt asked the new Metro board Chair Peter Benjamin why Metro's governing board lists oversight of funding and expansion among its core duties in the agency's official procedures but does not include safety?

The answer was less than satisfying. According to the Post,

"Benjamin agreed that the description should have included safety but said that board members rely on managers to bring exceptional concerns to their attention because of the large number of safety issues the agency faces every day."

Huh? There are so many "routine" safety issues that safety is not among the Metro Board's core duties, and only rises to their attention when it becomes an exceptional safety event?

Funding is a constant problem at Metro as well; so why is that considered a core duty?

The Post also reported that Metro Acting Deputy General Manager David Kubicek blamed the safety problems all on a few individuals - the classic management cop out to avoid any responsibility or accountability.

The hearings continue today.

The Conversation (0)

Quantum Error Correction: Time to Make It Work

If technologists can’t perfect it, quantum computers will never be big

13 min read
Quantum Error Correction: Time to Make It Work
Chad Hagen

Dates chiseled into an ancient tombstone have more in common with the data in your phone or laptop than you may realize. They both involve conventional, classical information, carried by hardware that is relatively immune to errors. The situation inside a quantum computer is far different: The information itself has its own idiosyncratic properties, and compared with standard digital microelectronics, state-of-the-art quantum-computer hardware is more than a billion trillion times as likely to suffer a fault. This tremendous susceptibility to errors is the single biggest problem holding back quantum computing from realizing its great promise.

Fortunately, an approach known as quantum error correction (QEC) can remedy this problem, at least in principle. A mature body of theory built up over the past quarter century now provides a solid theoretical foundation, and experimentalists have demonstrated dozens of proof-of-principle examples of QEC. But these experiments still have not reached the level of quality and sophistication needed to reduce the overall error rate in a system.

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