LOCATION:
A design and construct scheme to lower the cruise berth by 2.4m, extend it by a further 40m and add a freestanding, dolphin, mooring structure.
First cruise ship to arrive on berth, Majesty of the Seas
Lowered and extended berth with dolphin mooring structure
The berth now extends to 255m, enabling much larger ships to berth and therefore, making Portsmouth International Port much more attractive to the lucrative cruise market.
In summary, the key marine activities and sequencing were as follows:
- Remove scour protection to end of the finger jetty to allow pile installation.
- Install 21 tubular piles to the berth extension, up to 33m in length and 1.2m in diameter, into the seabed. (Up to 14m of each pile sits below water, with 3m above the waterline and 16m below bed level.)
- Install the new dolphin, a free standing mooring structure.
- Modifications to dolphin 1.
- Install the precast and in situ concrete to the deck extension.
- Install the fenders, walkway to the new dolphin, bollards and mooring hooks etc.
Land-based operations were completed in two distinct areas utilising 160t and 80t crawler cranes. A third, 80t crane barge was also deployed for lighter lifts.
Works sequencing included:
- Demolition of Area A
- Demolition of Area B
- Reconstruction of Area A (all materials lifted into area over Area B)
- Reconstruction of Area B
- Reinstatement of quayside furniture, fenders, M&E.
Arrival of Majesty of the Seas into port
Challenge
The project was to be delivered within a challenging timeframe. Works began on site in November and were due to finish before the start of the cruise season in the spring.
“Knights Brown were great to deal with. We felt from the very outset they worked with us rather than for us, demonstrating real collaboration in order to minimise disruption to the port.”
Anisa Koci
Port Master Plan Project Manager
Solution
To achieve programme, we worked simultaneously on two fronts. Marine-based operations were undertaken from a spud leg barge with 330t crawler crane, the largest hydraulic pile driving hammer in the UK, (with a drop weight of 20-tonnes, a 16-tonne shroud and a maximum impact weight of 300 tonnes) and a supply barge.
The crane assembled on the barge was towed to Portsmouth, where it was fitted with a BSP CG300 hydraulic pile driving hammer. When installing the dolphin, the crane and hammer drove the central pile before the 61-tonne carousel structure was lifted over it. The carousel was then used as the temporary works structure during the driving of the remaining six piles and remained in place as the permanent structure.
For the berth extension, the tubular piles, which weighed between 30 and 60 tonnes, were driven into the ground before being topped off in-situ.
Coinciding with pandemic restrictions, construction works at Berth 2 continued while accommodating additional ship movements required to keep essential freight services incoming.
Our team worked tirelessly to overcome resource and supplier deficiencies attributable to the situation, while responding to the demands of the situation. During this phase, despite the challenges, all beams and planks were installed alongside the new extension and several particularly large concrete pours were completed, including one of 800m3.
Throughout, we maintained a flexible approach to facilitate the port’s operations as they continued to serve their customers. This included facilitating temporary mooring and berthing arrangements to allow two cruise vessels to berth over the Christmas/New Year period and other vessels to berth during inclement weather. All other frequent ship movements were also maintained throughout.
Just prior to completion, Royal Caribbean Cruises requested to bring Majesty of the Seas into Portsmouth for repatriation of crew and to pick up stores. We were able to make the berth available at short notice, accommodating at 268m, the largest cruise ship to ever have berthed at Portsmouth.
Outcome
The new dolphin structure – including a prefabricated steel carousel – was built offsite and transported to Portsmouth by barge.
The carousel structure (weighing approx. 60t) was lifted and placed over a central pile, which served as a piling gate to drive the six perimeter piles through. Once all piles were driven to depth, the carousel was welded in position. This represented a quicker and more cost-effective solution than traditional methods.
The concrete units for the berth extension were all pre-cast on site by our directly employed workforce. Due to the short procurement timeframe, we elected for self-delivery to better control the operation. Reduced lead in times ensured units would be produced to meet critical programme dates and required quality in a controlled environment.
