Siemens Nexas - Braking Issues

Braking Issues

In late 2006 the trains suffered a number of braking discrepancies while in service; 14 trains overshot platforms in the space of three days. The 15 units involved in these overshoots were withdrawn from service for checks, and instructions were issued to the drivers to minimise further occurrences. By mid-January 2007, a total of 24 three-carriage trains had been impounded for testing after 20 further incidents of over-running stations since December 22, 2006. The Age newspaper reported that the incidents were being inspected by Victoria's independent transport safety auditor, and that the trains' braking system had been sent to Britain for tests. Connex had hired an independent consultant to oversee a review.

On the January 13, 2007, Connex stopped running the Siemens trains as 3-car sets until the braking issue was resolved, with the result that all services (including evenings and weekends) on the Caulfield Group were operated by 6-car trains. On January 29, 2007, Connex cancelled 37 peak-period services until further notice, due to the shortage of operational trains.

By February 1, 2007, 38 three-car sets were withdrawn due to continuing braking failures, meaning that almost half of the Siemens fleet (or around ten percent of the total fleet) was out of revenue service. Amidst the media reporting an escalating problem with the risk of the entire fleet potentially having to be suspended, Siemens issued a statement on January 31, 2008 saying that they believed there had been no evidence during investigations of the braking failures that would require the entire fleet of trains to be withdrawn from service. Testing of affected trains was carried out on the Werribee line between Newport and Laverton, with soapy water sprayed onto the rails to increase the amount of wheel slip experienced, in an effort to replicate the brake fault. The entire fleet has now re-entered service, although with a restriction not to run single unit (3 car) operations.

In December 2008 train operator Connex commenced proceedings in the Supreme Court to claim damages from Siemens. Connex claims Siemens provided trains with a braking system that was "defective, faulty and inadequate", the trains being "not fit for their purpose" and were not of "merchantable quality". Sources told the Herald Sun that Connex may also attempt to claim compensation for loss of commuter confidence.

In March 2009, it was reported that three Siemens trains had been impounded due to new braking incidents in the week prior.

By December 2010 sanding equipment was trialled on set 773M-T-M in order to improve braking performance of the trains, and by February 2011 a number of in-service trains had also been fitted with the equipment. The sand boxes are fitted to the middle four bogies of each 3-car set.

In June 2011 installation of sanding equipment was completed across the entire Siemens fleet. Speed restrictions have now been lifted on all Siemens trains.

In September 2011 the Office of the Chief Investigator for transport safety found that “the relatively high frequency of overruns involving Nexas trains was neither the result of individual train defects nor any deficiency in train maintenance”.