The emergency braking problem caused chaotic scenes at Britomart and Newmarket stations in the morning commuter rush in December, when a driver's unfamiliarity with the new system prompted him to disable several other systems on board his train, disrupting 15 other services.
Auckland Transport chief executive David Warburton told his board this week, in his monthly business report, that Siemens Spain had undertaken a two-week investigation in New Zealand and was "working to improve ETCS [European Train Control System] reliability."
The system is the first of its kind to be installed in Australasia, and it is designed to automatically apply emergency brakes to stop trains if they pass red signals, as well as to automatically moderate speed such as in tunnels and around bends.
Auckland train operator Transdev said after unveiling the system in November, 2013, in a joint project with KiwiRail that it had undergone "strenuous testing to ensure it is fit for purpose in NZ conditions."
But within days of the introduction of the first electric trains to the Onehunga line in April last year, train drivers were complaining that they were being over-ridden by the system's speed controls, making the newcomers slower than the elderly diesel clunkers they were replacing.
Auckland Transport acknowledged to the Herald in December, in response to an official information request, that the extent of automatic warnings initially received by train crews when driving normally was "excessive" given their high levels of familiarity with routes.
Public transport group manager Mark Lambert said that once enough drivers had become very familiar with the new system, a trial of several different configurations of the warning settings was conducted.
That led to the adoption of new settings in July.
But the author of the message received today by the Herald suggests the system is still "overly-restrictively programming" how fast the new trains can go.
Spanish rail manufacturer CAF has meanwhile shipped 47 of the new trains to Auckland, of which Dr Warburton's board report said 35 had been "provisionally accepted" into his fleet.
That leaves just 10 three-car sets to arrive in Auckland before more can be added to the southern line and electrification can be extended to western services.
Auckland Transport electrification project manager Lloyd Major confirmed there was a problem with laser readings from electronic control transponders on what he said were a small number of the new trains.
He hoped the cause and a solution would be identified within the next week or two, following the Spanish engineers' visit.
Mr Major said the problem, although frustrating to those involving, did not pose any safety threat.
Speed wobbles
April 28, 2014:
First of 57 new three-car electric trains introduced, to the Onehunga line
May 4: Rail and Maritime Transport Union complains that drivers are becoming frustrated with automatic speed over-rides on what are otherwise "very good trains."
July: Speed settings adjusted after trials and consideration of driver feedback.
December 9: Morning rush-hour commuter rail services plunged into disarray after emergency brake stops an electric train outside Britomart, and its driver allegedly over-reacts by disabling several other on-board systems, stalling 14 other trains and prompting new investigations into control settings.
Last Thursday: 32 morning rail services are cancelled or curtailed and 64 others delayed after a diesel train breaks down at Papakura Station, blocking the tracks, and a second diesel sent to clear it also breaks down
This week: Auckland Transport says it wants to bring forward from August the completion of its electrification rollout, for an early retirement of most of its diesel fleet, but rail industry workers remain concerned about bugs persisting in some of the new electric trains.
