THORCO CLOUD – Development of Traffic Management Protocols

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‘THORCO CLOUD’ was a two-hold general cargo vessel fitted with two offset 80-tonne cargo cranes. Her principle dimensions were length 145 metres, beam 18 metres and a light displacement of 4,446 tonnes. At the time of the incident, she was laden with about 8,000 tonnes of steel products.

‘THORCO CLOUD’ departed from the port of Batu Ampur, Riau, Indonesia on 15 December 2015 laden with a full cargo of steel products onboard and was crossing the Singapore Strait to commence her voyage towards discharge ports in West Africa when she was involved in a collision with the tanker ‘STOLT COMMITMENT’ which was proceeding in an easterly direction along the traffic separation scheme. As a result of the collision, ‘THORCO CLOUD’ was split into two sections and subsequently sank in the east bound lane of the Traffic Separation Scheme (TSS) to the North East of Batu Berhanti beacon.

The two wreck sections were lying approximately 1,740 metres apart in approximately 70 metres water with a clearance of 43 metres over the wreck. The image shown below provides an indication as to the location of the two wreck sections within the eastbound lane of traffic separation scheme within Singapore Strait.

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Due to the location of the wreck, the vessel’s P&I Club initially called for the wreck to be surveyed. The scope of work was designed to assist with the planning of the wreck removal. This scope was then increased to include the removal of the fuel oil remaining within the wreck.

Solis Marine was engaged by the appointed contractors to provide marine advice in relation to the proposed survey work, and in particular to assist the contractor with developing procedures to assist with the management of marine traffic during the project.

Following consultation with all parties which included contractors, the vessel owners including their P&I Club and consultants, Indonesian Marine Authorities (SEACOM), the Batam Harbour Master as well as the Singapore Maritime and Port Authority (MPA) and Vessel Traffic Services (VTS), Traffic Management Scheme (TMS) Protocols were developed to provide the required procedures and guidance to all parties for the management of vessel traffic operating in the vicinity of the wreck site.

As part of the development and planning for the TMS Protocols, a detailed study was undertaken using current AIS data to determine typical traffic patterns and the routes taken by marine traffic using both traffic separation scheme and inshore zones in the vicinity of the wreck site. This study provided detailed information on the movements of all vessels transiting the TSS, and in addition also identified the type and number of vessels passing the wreck site on a daily basis.

The TMS protocols that were developed, provided for the establishment of an exclusion zone to be created within the east bound traffic lane. This exclusion zone, which was demarcated using cardinal marks and covered both sections of the wreck, was designed to minimise the disruption of marine traffic using both the normal route as well as the deep-water route. The exclusion zone provided a safe working area for contractors allowing them to carry out the required work scope at the wreck site.

Procedures were implemented to coordinate the efforts of both VTS operators and the watchkeeping officers onboard the survey vessel in order to ensure that all marine traffic approaching the exclusion zone was appropriately warned in adequate time. Procedures were also developed to ensure that watchkeeping officers on the survey vessel could evaluate any potential risk developing at an early stage and implement appropriate measures in good time to avoid any potential situation with an approaching vessel escalating in an uncontrolled manner.

The heatmap reproduced below shows all marine traffic passing the exclusion zone over a 12-hour period during the survey operation. It clearly demonstrates the impact that the establishment of the exclusion zone had on the flow of marine traffic around the wreck site. In this image the survey vessel can be seen working over the bow section which was located to the eastern end of the exclusion zone.

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12-hour period during survey operations on 14 March 2017

The survey and oil removal phase of the operation was completed between March and June 2017. Following this, Indonesian authorities still required the remaining wreck sections of ‘THORCO CLOUD’ to be removed. Following a lengthy evaluation process considering the location and depth of the wreck, a wreck removal contract was subsequently entered into with the contractors that were deemed most suitable to complete the work.

Solis Marine was again appointed by the preferred contractors to assist with initial planning, liaison with the marine authorities and the development of appropriate traffic management procedures for the wreck removal operation which was successfully carried out between June and October 2019.

The successful completion of both the survey and oil removal phase as well as the wreck removal phase of the operation involving ‘THORCO CLOUD’, in one of the busiest vessel traffic routes in the world, demonstrates that with careful and proper planning, full cooperation of all parties involved and with close monitoring during the operational phases, complex marine operations can be carried out in a safe manner without any significant incidents occurring.

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