Conspiracy Of Constraints – A Rail Freight Perspective

Transport Forum Presentation from DR Leo Petkoon, Chief Executive Officer LP Projects.

The biggest potential to improve freight throughput in South Africa is in the way terminals are designed, in particular origin and destination, as well as intermediate interchange facilities, and junctions, says Dr Petkoon.

Unashamedly a rail supporter he believes with this infrastructure in place wagon-bound freight can be relayed through the system from origin to destination with the minimum delay.

“At present when the limitations of rail are discussed then speed is often at the top of mind. Trains are moving faster, and it is a very exciting development, and the question arises how can we move cargo faster on rail? Another discussion point is that of gauge and how that impacts on the rail offering.”

Dr Petkoon, however, believes that speed is not as necessary for freight rail as many believe. Using the country world-class iron and coal railway line performance as examples, he told delegates these were successful not because of speed or railway line gauge, but rather because so much thought had gone into the concept development from pit to port.

Comparing the average performance of rail freight wagons in South Africa and the United States, Dr Petkoon found that the average turnaround time was not necessarily dependent on the speed of the trains.

“In the US when looking at the average performance of rail freight wagons the turnaround time is about 240 hours, the average length of haul 1200km and the average distance between loads 1560km. The average line speed is about 60kph and the forward motion time loaded is 20 hours and the forward motion time for empties 6 hours.”

In comparison South Africa’s turnaround time is 288 hours, the average length of the haul 550km, the average distance 715 km and the line speed also 60kph. The forward motion time loaded is around 9,2 hours and the forward motion time for empties 2,8 hours.

“What we see is that there is a lot of dwell time in the movement of rail freight wagons. From waiting for inspection and preparation to placement at the origin, collection at dispatch yards, assignment to train in dispatch yards, at signals and routes, crossing with oncoming trains until having to be detached from the train, unloaded and collected for redistribution.”

In total, around 45% of the cycle time of general freight rail wagons was stationary en route, while 26% of the time was for loading and unloading. Further research in the US found that terminal performance impacted network efficiency. “A statistically significant relationship was found between the average system-wide terminal dwell time and average manifest train speed. As average dwell time increased, average manifest train speed decreased. This is the spider we have to fight,” he said. “Speed is important, but really why hurry up to wait longer?”

Dr Petkoon said instead of focusing on moving trains faster it was necessary to think more about where to put terminals.

“From a South African rail perspective, there are probably less than ten major terminals that make a significant contribution to the average wagon cycle time. Terminals at harbours almost invariably have the biggest impact on freight wagon cycle time. A new and creative focus on the flow of traffic through terminals could reduce the dwell time of rail wagons significantly. There is a causal relationship between wagon cycle time and wagon capacity required to meet demand. Reduced cycle time could free up a significant amount of rail wagons.”

Related News Articles