Distributed Power: Has its time come in New Zealand?

Every decade or so, a major operational change tends to take place in global freight railroading, particularly in North America, and New Zealand has generally kept up with these changes.  As an example, in North America in the mid 1980's, technology enabled removal of cabooses from freight trains, leading to a reduction in staff and costs.  New Zealand Railways embraced this revolutionary change without delay, and the final guards vans disappeared from trains in New Zealand even earlier than the final cabooses vanished in the United States.

Another example is with train crewing.  When the United States reduced train crew size from four to three, in conjunction with removal of cabooses, NZR reduced crew size from three to two for the same reason.  Within a further five years, improvements to communication systems enabled the United States to further reduce crew size from three, to just two.  Again, simultaneously, NZR embraced the same technological improvements and reduced its crew size from two, to just one.  In the yards it was similar, with shunting crews being signicantly reduced in size in the US and NZ at much the same time, for the same reason (better radio systems).

In some cases, New Zealand lead the way with these mini revolutions.  Widespread use of remote control shunting came to New Zealand some five to ten years ahead of most of North America.  Removal of flashing lights from level crossing barrier arms, replaced by reflective strips, is only now beginning to occur in North America, close to 20 years behind this change being made in New Zealand.

In other areas we kept up, albeit on a much smaller scale.  When freight train sizes were increased in America in the 1980's, with more motive power being assigned to trains, the same soon happened here.  Many large trial trains were run throughout the country, in aid of setting new load schedules.  Three DX's on a lengthy Murupara log train was a notable trial at the time, even making the 6 o'clock news.  Single headers were replaced with double headers, and triple headers became common.  Fewer, but larger trains was the catch phrase.

But another revolution began to take place in North America in 2007, that to date, has passed us by.  Rolled out over a five year period, and largely fully in place by 2012, has been the change to routine use of Distributed Power (DP).  Once the domain of specific heavy-haul railroads, DP was extended to ordinary freight trains on a trial basis during 2005 and 2006, by most of the class 1 railroads in America.  It quickly took off, and today, most freight trains now operate with locomotives on both the head and rear of the train, and often in the middle as well.

The obvious change this has lead to is train length.  3000 metre long freights are now in widespread use across America.  America has always had big trains.  100 car, 2000 metre jobs could be seen in the 60's and 70's, but today, 170-180 cars is commonplace.

The advantages with DP are significant.  Having locomotives pushing from the rear, or pushing and pulling in the middle, greatly reduces drawgear stress where it is at its highest, near the front of the train.  Lateral friction is also greatly reduced, meaning less wear on wheels and rails, whilst also reducing fuel consumption of the locomotives.  Slack throughout the train is also better controlled, with fewer run-ins and pull-outs, and instances of train pull-aparts are greatly reduced, to the point of near elimination.  Braking is enhanced significantly, as air pressure changes take effect much sooner when commenced from two or three points along the train, rather than from just the front.

There are also disadvantages however.  Making up and then breaking up a train, takes longer with the need to add locomotives in different sections.  DP technology itself comes with a cost.  Buying it, and then fitting it to the fleet.  But these costs have been found to be more than outweighed by the advantages the technology has to offer.  Overall, costs come down.

To their credit, KiwiRail have pursued a new round of train size increases in recent times, that has largely gone unremarked in railfan circles.  A few years back, NIMT freights were increased from around 35 wagons to around 45 wagons.  1800 tonnes up the spiral was set as a goal, and today, 2000 tonnes is being seriously looked at.  On the Murupara Branch, log trains are being increased from 35 wagons, to 40, then to 45, with 50 rumoured to be a new target.  Metroport trains are getting bigger, and there is the often talked about plan to get Midland Line coal trains up to 45 wagons, and some 3000 odd tonnes, which would make them the heaviest trains to operate in this country.

In some cases the changes are being implemented, but in others, and in particular the Midland Line coal trains changing to 45 wagons, the proposals have stalled.

Is there a place for DP technology to not only provide solutions, but to take our train sizes and weights to even higher levels?   I believe there is.   But it does require some change in thinking on behalf of KiwiRail.  To a degree it makes sense to run smaller, more frequent trains in New Zealand.  The cartage distances are not that great, the terrain can be difficult, and wagon utilisation is at a premium.  But with all the new wagons being purchased by KiwiRail, and higher horse power on offer from the new locomotives, the existing trains on the network are beginning to reach capacity in terms of length and weight.  Adding more and more trains will reduce network timekeeping, so I believe a balance needs to be found between adding more new services, and adding more tonnage to existing trains.

Photo courtesy Phil's Loco Photos

Auckland to Wellington is some 665km by freight train, and while relatively short on an international scale, is still a reasonable distance.  It may be worth spending a bit more time at Southdown or Westfield adding locos to the rear, if it enables say, 3000 tonnes to be pushed up the spiral.  Getting at least 50% more tonnage onto existing trains, with an overall reduction in expenses, may just be worth doing.  Longer make up roads, and longer crossing loops would of course be required, but would enable long term savings that will make rail more competitive than it currently is.  Furthermore, if the same locomotives are left on the train right through, the extra time needed to make up the train in Auckland, may be offset by a faster transit through Hamilton and Palmerston North.  2 DL on the front, and 1 DL on the rear, and just keep going, all the way from Auckland to Wellington.

Down south, DP may just enable those 45 wagon coal trains to operate, without the problem of drawgear breaks.

There is one outstanding challenge to DP in the New Zealand context. The terrain will likely result in some momentary loss of telemetry between leading and rear end locomotives.  But DP technology takes this into account, and is designed to automatically recover from short signal losses.  I'm sure this issue could be managed effectively.

Should KiwiRail consider DP, it will mark a new round of revolution to our train scene.  It will put us back on track with international best practice, and has the potential to help KiwiRail reach its goal of becoming self sufficient through more efficient operations.