For as long as trading has taken place in the world, maritime ports have played a vital role in the transport of goods. In ancient times, people commonly made use of “natural ports” that were available in bays and estuaries. However, gradually, more work had to be done to keep these ports accessible, due to sedimentation, changing waterway routes and dynamic coastlines.
For many centuries, nature has been the major cause in bringing about the need to adapt existing ports and create new ones. However, a second crucial factor has emerged since the beginning of the 20th century, after vessels started to increase in size and volume.
The growing demand for energy sources created by industrialisation propelled developments in the oil and gas sector, and consequently generated a marked rise in shipping. In particular, bulk carriers for the transport of oil, coal and minerals have seen their size, as well as their draft, increase exponentially over the past century. As a result, the requirement for dredging has become one of the main activities in the port construction and development business.
Which dredging equipment is required?
By the beginning of the 20th century, mostly mechanical equipment, such as grab dredgers and bucket ladder dredgers, were deployed for port construction projects. After World War II, hydraulic dredgers gradually took over their role and became progessively more important.
This development accelerated the initiation and growth of some of the largest ports in the world today. The ports of Rotterdam, Singapore, Shanghai and Antwerp couldn’t have been created without the help of modern trailing suction hopper dredgers (TSHDs) and cutter suction dredgers (CSDs).
What activities are dredgers involved in?
In port construction work, dredgers are needed for several activities, with deepening and excavating operations among the most important. Access channels, fairways and harbour basins that offer sufficient depth are vital for their continued existence as a port. In some instances, existing water systems can be deepened, whereas in others, new ones need to be excavated entirely.
Another operation where dredgers constitute a vital tool, is the creation of new land for port infrastructure. This is an activity that has grown in importance over the past decades due to the expansion of existing ports, as well as the need to create new ones in areas that lack suitable land.
Recently, some ports have even been built entirely on new land reclaimed from the sea. Known as “offshore ports”, examples include Khalifa Port in Abu Dhabi and the Yangshan Deep-Water Port near Shanghai. For all these activities, TSHDs and CSDs are indispensable pieces of equipment.
The importance of soil types
The type of dredger most suited to a particular job is largely determined by the soil conditions.
In the case of hard material, such as rock, this has to be dredged using heavy duty CSDs.
If soft soil is present, it might be necessary to remove it entirely. This process improves the soil conditions so that the foundations for port infrastructure, such as quay walls and breakwaters, can be laid. In these cases, trenches have to be dredged, which may not only require TSHDs but also mechanical dredgers, such as grab dredgers and backhoe dredgers.Read more about different soil types here