The port of Durban is South Africa’s largest container port handling approximately 2.6 million TEUs of container movements each year. The total numbers of containers continues to grow, although at a relatively slower pace than in earlier periods. In the period 2003-2013 container numbers have increased from 1.5 million TEUs to 2.6 million TEUs per annum (173 % in 10 years).
The changing dynamics of the container trade worldwide are evident in the statistics the port of Durban. As shown in Figure 1 below, the increase in container growth was very rapid between the period 2003 and 2008 but this has now slowed significantly due to the worldwide recession, the depressed economic conditions in South Africa and the reducing amount of break-bulk being converted to containerised cargo.
Figure 1 – Vessels, and TEUs at Port of Durban (2003 – 2013)
Source : TNPA ; SAFTI
At the same time there has been a changing pattern of vessel size (gross tons) over the period. There has been a steady increase in the average size of the vessels that are calling at the port (from about 20,000 GT in 2003 to 40,000 GT in 2013).
The trend in growth of vessel size is interesting, as call sizes in TEUs per vessel reduced from 2004 to 2010 and have now recovered to equal the average in 2003. Average call size has changed over the period, as shown in Figure 1, but analysis of the annual averages using the cusum technique shows that despite a spike in 2012, call size has remained relatively constant over the past 10 years in the range 1500 – 2400 TEUs per call as shown in Figure 2 below.
The number of container ship arrivals increased between 2005 and 2010 but numbers are now decreasing as shown in Figure 1. The current situation is that relatively larger ships are delivering approximately the same numbers of boxes at each vessel call.
Figure 2 – Cusum analysis of Annual TEUS, Vessel GT and TEUs per Vessel Call – Port of Durban (2003-2013)
These trends in the statistical data released by Transnet National Ports Authority, give clear indications of the difficulties being experienced by the port authorities in trying to accommodate changing trends, with a need for deeper berths, longer berth space, and the problems of fitting longer vessels into the port’s somewhat inflexible wharf structure. In addition, the back-of-port logistics becomes increasingly complicated when it is necessary to juggle vessels to accommodate the mix of small vessels and large ones, which with space for moorings, often need two berths for one vessel.
Figure 3 – Two Larger Vessels Using 3 berths with 7 multi-lift cranes
Photo : Christison
The management problems are also exacerbated, not only by the berth lengths, but by the fact that the current layout does not allow efficient allocation of cranes around the total berthing area as they are necessarily locked into the segmented berth geometry and often cannot be allocated to match ship requirements. The use of two different landside transport options, straddle carriers (SCs) at Pier 2 and mafi trailers and rubber-tyred gantries (RTGs) at Pier 1 compounds the stacking problem when containers are transhipped from one Pier to the other.
Figure 4 – Rio Madeira (286 m length) shares berths 105-107 with one smaller ship and 3 cranes idle
Photo : Christison
The annual average number of container vessels reduced to 1226 p.a. in 2013 and it would be relevant to examine the frequency of arrival of different call sizes (numbers of TEUs landed and shipped per vessel), but this information is not readily available. As a basis from which to examine the implications of call size Figure 5 shows an estimated distribution pattern of different call sizes and number of vessels per week, using a normal distribution around the average call size.
Figure 5 – Estimated Weekly Distribution of Vessel Arrivals and Call Sizes – Port of Durban (2012 and 2013)
Source : SAFTI
As shown in Figure 5 it can be estimated that there were approximately 5 vessels per week with calls of over 3000 TEUs in 2012/2013 (about 300 p.a.) and about 11 per week (560 p.a) with call sizes of 600-2999 TEUs. The other calls were below 600 TEUS. The problem is that call sizes do not correlate with Vessel GT as shown in Fig 2 above, so that the current trend is likely to be negative in terms of berth productivity.
All of the foregoing, underscores the urgent need for reorganisation, acceleration of the capital plans to improve berth layouts, and the pressing need for research into the options for increasing efficiency of the back-of-port logistics as a means to optimise infrastructure usage, improve vessel turnaround times and reduce port logistics costs.
The port throughput and terminal handling capacity and methods has major implications for the road transport industry that services the import-export container industry as well as for the eThekwini Metro in terms of road usage and congestion around the port.