Wednesday, October 28, 2015

The County Council was aware of the feeble beams of the escalator – New Technology

       

An escalator at the station Östermalmstorg opened like a trapdoor February 14 this year. The woman who had just stepped on fell and pinned.

The escalator, which was manufactured by Asea in the 1960s, was equipped with two safety systems. Yet it stopped not until a passerby pushed the emergency button.

Emergency services worked for a long time to dislodge the woman, who risked losing his leg. Since then, she has undergone several operations.

New technology has taken note of two consultant reports on the accident that the County Council’s traffic management ordered. The company Dekra has conducted a technical investigation of the accident, while Inter Fleet has studied the organization and procedures. Both investigations show that the accident could have been prevented.

Eight days before the accident, on February 6, Dekra had blown the whistle on that particular type of the escalator. The company had investigated another escalator of the same model at Östermalmstorg who had suffered repeated errors.

“The preliminary findings of serious concern to us then step leg (walking beam) breaks down quickly at a seemingly limited load. (…) We recommend that you as facility operator takes escalators with this design stages leg and / or materials from operation, “wrote Dekra.

Five days later, a meeting was held on traffic management. It was the last chance to prevent the accident, noting the Inter Fleet afterwards. Instead it was decided to keep the escalator continues to run, but with extra supervision. In the meeting notes recorded that Dekra was with the decision. In retrospect mean Dekra it never sued.

On 14 February, the accident occurred and the woman was pinned.

Deputy Head of the Traffic Department, Frederick Cavalli-Björkman, was one of the participants in the meeting.

– With hindsight we would of course have turned off. But we understood that it was not so serious. It is a mistake we have made, he said.

Can a consultant be clearer than writing that he is concerned about and recommend a shutdown?

– No, but after that we had the meeting when we discussed the matter. But it is clear that we have made a number of judgments that were not okay, says Fredrik Cavalli-Björkman.

After the accident, Dekra assigned to investigate what caused it. The result shows that the escalator had both in material and workmanship. The steps have various types of beams, and two of the types substandard.

A beam-type in the form of U-profiles were tested and approved in 2007 but according to Dekra quality deficiencies. Among other things, there are pores in the casting that weaken the structure.

Unfortunately it is with lattice beams. They are not tested by any standard and can withstand about half as much cargo as U-profiles.

Both beam types can rupture of the a traveler running or jumping on the ladder. The material is brittle and flaws therefore quickly without deformation, which is very risky in an escalator.

The direct cause of the accident is under Dekra to a beam burst about 15 steps below the accident stage. It is likely that it goes down, when someone jumped or ran down the stairs.

– It is sufficient that any sufficiently large adult stomps to the hard right on this model, says Bernt Åke Johansson, accident investigators at Dekra.

Crime and accidents in older Asea escalators have been common. Peter Andersson, DEKRA mission leader, considers that the problems should have been caught and corrected before.

After the accident, traffic management put in extra beams and wheel sensors in steps of 39 old Asea stairs. Thereby the steps are not able to open like a trapdoor.

The idea for this article came from New Technique anonymous tip service Techleaks.

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