Should Rail Run In A Storm?

in Featured General Trains by Jon C — October 28, 2010 at 4:47 pm | 9 comments

Numerous issues about commuter rail services in very bad weather have been raised in a Transport Accident Investigation Commission on the slip that derailed a Wairarapa passenger service.

KiwiRail and NZTA say they are working to implement the recommendations, while acknowledging it’s not always easy predicting slips along the rail corridor.

KiwiRail says trains passed the slip site up to an hour before the collision without any sign of an impending problem being evident.

Among the issues is just that -  In bad weather, when should commuter services stop running?

The rail report, released today, gives four safety recommendations to NZTA to address issues around the track inspection process, the severe weather warning system and the National Rail System Standard for incident response.
During the course of the inquiry, KiwiRail initiated several safety actions that were directly relevant to the Commission’s findings. The safety actions include the development of a slope hazard risk assessment for the rail network, improvements to the train control facilities and changes to the failure mode of the internal ‘S’ Car pneumatically operated passenger doors.

The incident happened in July last year during a wild winter storm in the capital.

A scheduled commuter train travelling from Wellington to Masterton with approximately 240 passengers and crew in 5 carriages, collided with a slip that partially blocked the northern portal of Tunnel 1 on the Wairarapa Line. This point was about 4 km north of Upper Hutt station and about 1 km before the Maymorn station.

The locomotive and generator carriage were embedded in the slip and derailed, while the remaining carriages were still on the track but standing within the tunnel. Emergency services were called to rescue the passengers and crew.

The damage to the train was minimal and no injuries were reported. The Wairarapa Line was closed for approximately 5 days while the mud was cleared and the track repaired.
Police assumed management of the accident’s rescue phase using the New Zealand Coordinated Incident Management System (CIMS) and activated a full tunnel response. The locomotive from a following Masterton-bound passenger train was used to haul the rear 3 carriages from the disabled train back to Upper Hutt with all passengers on board.
The landslide had occurred suddenly, less than one hour before the train collided with it. It had partially blocked the northern end of Tunnel 1.

The landslide was a first-time occurrence on a risk-prone slope that was covered in regenerating bush. The Transport Accident Investigation Commission determined that the landslide occurred from natural causes after 62 millimetres (mm) of rainfall fell in the area during a 6-hour period.
Train 1608 had been travelling at normal speed when the driver saw the landslide, but he had had insufficient clear distance ahead to stop the train before impact. Network control had not warned the driver that the Wairarapa Line was subject to both heavy rain and strong wind warnings at the time.
Network control had received an updated severe weather warning message to the active severe weather event 24 hours before the accident, but network control had not distributed this message and several following messages to area managers.

And the report says even if it had, the area manager for the Maymorn area would not have received them because he was new to the job and his contact details had not been recorded in the system.
The track inspection regime was based upon checking specific items along the track, so was not capable of assessing the potential risk of slope failures, although this type of risk was common in the Wellington area and documented in a railway structures guidance manual.
The severe weather warnings and track inspection systems, if followed, “could have mitigated the consequences of a slip falling across the track but would not necessarily have prevented trains running into it.”
The passengers were kept in the carriages within the tunnel for some 3 hours.

The inquiry report says that improvements in the communications around the emergency response and rail recovery operations could have reduced this time by up to 30 minutes, but the recovery was safely coordinated and resulted in no injuries to the passengers and crew.

“The location of the derailment and the general disruption to transport services throughout the region due to the severe weather meant the response to this event was reasonable.”

KiwiRail Chief Executive Jim Quinn says KiwiRail has already completed a draft of a study which assesses and ranks potential slip hazards in the Wellington Metro area.

“We have made progress on this work but we still have some way to go,” he said. “While we consider the study useful, it cannot be infallible in predicting land movement along the rail corridor.

“Under this study, the Maymorn slip is unlikely to have been identified as an area of extreme risk before the slip occurred.”

Mr Quinn said KiwiRail was also working with NZTA on improving the response to severe weather warnings.

“Our Network Control Centre immediately addressed concerns raised about the systems that relate to interpreting and distributing information about severe weather warnings,” he said. “We are continuing to work on improvements.

“It’s not an easy issue because apart from alerting infrastructure and operational staff, our only recourse is to impose speed restrictions on trains. This is a useful means of mitigating risk but it is not a complete panacea. Even with a speed restriction in place, the Maymorn collision is likely to have occurred.”

A third area identified by TAIC was a review of track and structures inspection regimes. “We will work with NZTA on a review,” said Mr Quinn. “But we currently have robust systems which involve the inspection of both track and structures by suitably qualified people.

“To a significant extent, we rely on the observations of train staff as well as the work of track and structures inspectors. In the Maymorn case, trains passed the slip site up to an hour before the collision without any sign of an impending problem being evident.”

Mr Quinn said KiwiRail noted TAIC’s finding that the response to the event was “reasonable” given the location of the derailment and the significant disruption to transport services around the region caused by the severe weather.

“Our focus throughout the event that unfolded was to keep our passengers safe. TAIC recognises this in its report when it says that the recovery was safely coordinated and resulted in no injuries to passengers or staff.”