A year ago yesterday, and in the middle of Auckland’s second lockdown, speeds on the entire Auckland rail network were slowed to just 40km/h as a safety precaution after Kiwirail revealed wear on the tracks, known as Rolling Contact Fatigue (RCF), was more widespread and severe than they previously realised. At the time they said they urgently needed to replace 100km of track across the network.
A week later they shut the entire Eastern Line between Quay Park and Westfield down for two weeks in order to accelerate that work. That two weeks extended to four weeks and over the subsequent six months or so the rest of the rail network experienced various closures as Kiwirail worked to fix the issues. As of early February, with just the Pukekohe line to go, Kiwirail said:
“So far we have replaced more than 112km of damaged rail which is 84 per cent of the required re-railing work overall. At the same time, we’ve replaced close to 20,500 sleepers and destressed 95km of rail track.
They now say they’ve replaced 130km of rail which is significant when you consider there’s just over 180km of track passenger services run on.
After thinking the work was all done, more issues surfaced in mid-June which saw Southern Line slowed down again and services reduced as a result which lasted till late July. This and issues like left over rail causing $250,000 of damage to Auckland Transport’s trains and Kiwirail prioritising of freight prompted letters from the Mayor and AT and included calling on the government to put people with asset management and public transport experience on the Kiwirail board.
The impact off all the disruption and unreliability on train ridership has been significant. Following the first COVID lockdown usage on all modes of public transport was recovering compared to the same time pre-covid at a similar rate – rail was only about 5 percentage points lower than buses. But as we came out of the second lockdown we saw a notable change with rail usage lagging significantly with rail about 17-20 percentage points lower than buses. Notably ferries also saw extra benefit in September following the damage to the Harbour Bridge and have recovered much better this year.
There were three key areas studied, the track, the vehicles and the wheel rail interface (WRI). Here are the findings for each of them.
The report highlights that while there has been investment in network improvements, such as double tracking, new stations, new signalling, electrification and new trains, the “existing track and civil infrastructure, including historic formation was not upgraded under any of those programmes“.
Under the section on the track there are four key areas.
- Historic under investment in the track asset prior to 2014 up to September 2020
- Insufficient rail grinding from 2015 to 2020
- The existence of multiple sites where the track condition is sub-optimal in engineering factors known to accelerate the growth of RCF:
- Track geometry and gauge exceedances including at welds and bolted joints
- Aged timber sleepers unable to hold rail in place adequately
- Historic wheel burns/squats causing sudden dynamic loads
- Sub-optimal application of cant, mainly from uncorrected past practices
- Significant sections of the network have low track modulus (low combined stiffness of rail, sleeper, ballast, and formation), at times aggravated by poor drainage.
- The speed of RCF propagation varies between very dry and very wet climates. It is likely that Auckland’s climate has been a partial contributor to the accelerated growth.
Interestingly the report sates:
In 2014, prior to the commencement of the new electrified service, AT engaged Network Rail Consultants to evaluate the overall state of the infrastructure. The evaluation effectively concluded that substantial investment (~$100m) in the AMRN [Auckland Metro Rail Network] track assets was needed to ensure it would be fit for purpose for the proposed EMU operation. This investment was not approved and the parties instead relied on increased inspections for safety, track speed restrictions, and accepted the infrastructure would provide lower levels of service.
I wonder who declined this investment. We’re now paying $200 million to fix the network so I wonder how much of this is a case of penny pinching coming back to bite us, especially as they also note there has been rapid and non-linear, accelerated growth in RCF. A separate part of the report notes rail wears in a linear pattern to a point but after that happens exponentially. To avoid that Kiwirail need to do the maintenance before reaching that tipping point.
Back when this issue first emerged there was a lot of finger pointing at Auckland’s electric trains, though given this issue also exists outside of the electrified network that was always a long bow to draw. However, the report does note some issues with the trains as a result of trying to make the trains more comfortable for passengers.
- The AM class EMUs were designed with a high primary yaw stiffness to improve passenger ride comfort. However, this increases a vehicle’s propensity to cause RCF. The modelling commissioned did not fully assess the “RCF damage index” relating to this class of vehicle.
- The AM class EMU wheel profile was modified by the manufacturer from the KR standard profile to avoid anticipated high wheel flange wear, itself related to the high vehicle stiffness. During running rights approval KiwiRail acknowledged that modelling by the supplier of the proposed alteration, showed it to be safe, but had concerns that the change would impact on the rail maintenance requirements. Modelling in this study showed the profile change increases the formation of RCF over the KR standard profile.
On that first point, in the more detailed part of the report it suggests high stiffness is only an issue where the track conditions aren’t good, which they weren’t
The vehicle stiffness has been shown to have little impact on RCF for perfect track. However, logic, literature, and the Matangi design experience indicate that a vehicle of high stiffness, on low modulus track with maintenance tolerances that are more suited to a freight railway is likely to accelerate RCF.
That last line highlights the real issue, Kiwirail were maintaining the Auckland network to the standard of a little used freight railway.
Wheel Rail Interface
The points for the wheel rail interface are all covered above however they’re listed below too..
- Lack of comprehensive grinding since 2015
- Lack of artificial rail inclination on track structures
- Lack of optimised wheel and rail profiles
There are 8 recommendations in the report. These can generally be summarised as
- Fix the tracks
- Set up a 30-year maintenance programme to keep the network up to spec
- Optimise the rail profile and the wheel profile of the electric trains to reduce issues.
For both those last two there is emphasis on the need for the various organisations to work together in order to achieve the lowest total cost of ownership
Finally, one other thing I noticed in the report. There’s a section which gives a development timeline for the Auckland network. It includes this comment perhaps suggesting why, despite buying enough trains for all services (except Onehunga) to be 6-car trains, it’s not uncommon to get a 3-car train at peak times.