Main Navigation Channel Research Articles

Analysis of emission characteristics associated with vessel activities states in port waters

This study investigates AIS data from March 2019 to February 2020 in Shanghai Port waters. The ship activities of berthing, waiting, and ingress/egress are extracted in detail to elucidate the emission characteristics of ships in Shanghai Port, differentiating emissions patterns across various ship activity. The findings reveal that the top three pollutants within Shanghai Port are CO2, NOX, and SO2. Container ships have the highest emissions, followed by bulk carriers. Berthed container ships and oil tankers exhibit the highest emission. Waiting container ships emit the most, followed by oil tankers and bulk carriers. Among ships entering and leaving the port, low-speed navigation produces the most emissions, followed by maneuvering and steady-speed navigation. Emission hotspots include the Yangtze River Estuary Anchorage and the main navigation channel into and out of the port. This study offers robust data support for an in-depth understanding and evaluation of ship emission characteristics in Shanghai Port.

Field Measurements of Bridge Pier Scour in a Curved Channel

Pier scour is the most common cause of bridge failures, so the problem for the erosion of soil surrounding a bridge foundation has attracted extensive attention. The Jiaxing-Shaoxing Bridge (JSB) is located in Jianshan bend of the Qiantang River Estuary (QRE). The special flow structure and bed morphology of the bend makes the scouring characteristics of the piers particularly complex. Based on the results of Multibeam Echosounders for topographic surveying in recent six years, the scouring characteristics of pier foundation of a main navigation channel of the JSB are analysed in this paper. The results show that with the implementation of the reclamation project in the QRE area, the river channel has been gradually narrowed, coupled with the sharp reduction of the sediment entering the sea of the Yangtze River, the river regime swing in the QRE has changed significantly compared with that in the original design stage of the JSB. Under adverse river regime hydrological conditions, the riverbed erosional depth near the bridge is remarkable, and the local scouring depth of the pier is superimposed, which significantly will reduce the minimum elevation of the bed around the pier.

Large-scale morphological changes and sediment budget of the Western Scheldt estuary 1955–2020: the impact of large-scale sediment management

Abstract In the Western Scheldt estuary, like in many estuaries, safe navigation, flood protection, and ecological targets require a balanced and sustainable sediment management. A thorough understanding of the morphodynamic functioning of the estuary and its response to changes in hydrodynamics (natural sediment transport) and large-scale interventions is imperative. This paper presents a detailed overview of over 65 years of morphological changes and a comprehensive sediment budget of the Western Scheldt estuary that is based on analysis of a unique series of frequent bathymetric surveys and historical data on human–sediment interactions of dredging, dredge disposal and sand mining. Solving the sediment budget reveals an annual sediment import of 2.2 million m3. The highest sediment imports occurred between 1980–1994 and 2005–2020 (2.9 and 3.7 million m3/year). A 1.3 million m3/year net export prevailed between 1994 and 2005. Natural variations in the hydrodynamics (e.g., tidal asymmetry and amplification) and sediment transports cannot explain the derived temporal variations in sediment import rates. Anthropogenic activities play a dominant role. Capital dredging of the main navigation channel has led to channel deepening and significantly increased dredge and disposal volumes. Disposal on tidal flats and in the secondary channel leads to a long-term storage of sand and, consequently, a local increase in bed level and a sand deficit in the remainder of the system that results in increased sediment imports. Large-scale disposal in the western part of the estuary can (temporarily) reverse the sediment exchange between the estuary and its mouth area, as observed between 1994 and 2005. Apparently, large-scale anthropogenic reallocation of sediment by dredging and/or disposal as part of navigation channel improvement, sand mining or nourishment essentially influences the morphological development of the Western Scheldt estuary. This reveals responsibilities as well as opportunities of sediment management for the Western Scheldt and similar estuaries worldwide.

Characteristics of the Total Suspended Matter Concentration in the Hongze Lake during 1984–2019 Based on Landsat Data

The Hongze Lake is the fourth largest freshwater lake in China and an important lake for the East Route of the South-to-North Water Diversion Project. The water quality of the lake affects social development and the lives of residents. To assess the impacts of environmental changes and human activities on the distribution of the total suspended matter (TSM) in the Hongze Lake, we developed an algorithm that utilizes the near-infrared (NIR) band to estimate TSM based on in situ measurements. The algorithm was applied to Landsat images to derive TSM distribution maps from 1984 to 2019, revealing significant inter-annual, seasonal, and spatial variability. The relationship between TSM, precipitation, and wind speed was analyzed, and we found that: (1) The estimation model of TSM concentration in the Hongze Lake constructed for TM and OLI has a high accuracy, and it can be used to jointly monitor TSM concentration in the Hongze Lake for long-term series; (2) From 1984 to 2019, the concentration of TSM in the Hongze Lake showed a trend of first rising and then falling, with the maximum value in 2010 at 100.18 mg/L mainly caused by sand mining activities. Precipitation and wind speed weakly influence the inter-annual variation of TSM concentration; (3) The concentration of TSM in the Hongze Lake in summer is easily affected by flooding in the Huai River, and the concentration of TSM in other seasons is significantly negatively correlated with precipitation; (4) TSM is highest in the Huaihe Bay, followed by the Lihe Bay and Chengzi Bay. The main reason for this is that the input of the Huaihe Bay flows directly into this lake area and is also the main navigation channel. The results of this study are of great significance for the protection and management of the water environment of the Hongze Lake.

Relationship between adjustment of low water level and utilization of water depth in Shashi Reach in middle Yangtze River

Hydrological, sediment, and bathymetric data of the Shashi Reach in the middle Yangtze River for the period of 1975–2018 were collected, and the characteristics of low water level changes and their impacts on utilization of water depth for navigation were investigated. The results showed that, during the study period, the Shashi Reach riverbed was significantly scoured and incised, with cross-sectional profiles showing overall narrowing and deepening. This indicated a strong potential to improve the water depth of the channel. The analysis of the temporal variation of in-channel topographical features showed that the Taipingkou diara underwent siltation and erosion, with its head gradually scoured and relocated downstream after 2008, and the Sanbatan diara continued to shrink and migrate leftwards. Low water levels with the same flow rate over the study period decreased. For instance, from 2003 to 2020, the water level at the Shashi hydrological station decreased to 1.37 m with a flow rate of 6 000 m3/s. Furthermore, the designed minimum navigable water level of the Shashi Reach was approximately 2.11 m lower than the recommended level. In terms of utilization of the channel water depth, continuous scouring of the river channel is expected to result in a reduction in discharge at the Taipingkou mouth, which will improve the water depth conditions of the channel during the dry season in the Shashi Reach. With several channel regulation projects, the 3.5-m depth of the Shashi Reach would basically be unobstructed. This promotes utilization of the shipping route from the Taipingkou south branch to the Sanbatan north branch as the main navigation channel during the dry season. Considering the factors of current water depth and the clear width limitation of the navigation hole at the Jingzhou Yangtze River Bridge, this route can still be favored as the main navigation channel with a 4.5-m depth during the dry season.

3D upstream passability of novel river training structures by migratory fish in the river Waal

Longitudinal training dams (LTDs) are novel river training structures that divide a river into a main navigation channel and protected shore channels. High velocities at the inflows of shore channels constructed in the river Waal (The Netherlands) pose a potential bottleneck for migratory fish species swimming upstream. This study assessed the passability of the inflows using flow velocity datasets from governmental monitoring campaigns collected with an ADCP during high river discharges (Q = 3489–5066 m3/s at Lobith monitoring station). The swimming performance of several migratory fish species were estimated from their total lengths (TLs). A new 3D approach to visualize the flow velocity data using Voxler® software is presented.Gasterosteus aculeatus aculeatuswas the only fish species with an adult life stage unable to pass the 9 cases tested due to its small size. The juvenile European eel and thicklip grey mullet passed 1 and 0 of the cases, respectively. The most upstream inflow, located in the inner bend of the river, was the most passable. We recommend maximizing the cross-sectional area of the inflow sills in order to reduce the flow velocities experienced by migrating fish during high river discharges. This approach may be useful to assess passability at other locations and training structures.

Dynamics and management of siltation in a macro-tidal marina: The case of La rochelle marina, France

La Rochelle marina, in the south-west of France, is one of the largest recreational port in Europe. As many ports around the world, La Rochelle marina is not spared by siltation and has to face serious dredging operations over a period of 8 months per year. Consequently, there is a big interest in determining sediment fluxes in the area and implementing measures to minimise siltation and/or to optimise dredging operations. In the present study, a three-dimensional hydro-sedimentary model (TELEMAC-3D) was calibrated with field measurements from 2014 to 2019. Analysis of the in situ measurements (turbidity, bathymetric surveys, seabed elevation) showed that the macro-tidal influence and local wind-wave regime significantly contributed to the siltation in the marina. In order to minimise the cost and time associated with maintenance dredging, multiple scenarios have been tested numerically and subsequently analysed. Numerous sediment trap configurations were defined to focus the deposition of sediment in dredged traps and constructional measures were also assessed in terms of siltation reduction (e.g. entrance closure, narrowing entrances, Current-Deflecting-Wall). Numerical simulations showed that the best solution is to create a sediment trap at the downstream corner of the marina, along the main navigation channel, to intercept sediment particles arriving from the ocean. The constructional measures as well as the use of sediment traps inside the marina are not efficient in reducing siltation. These results highlight the importance of using operational numerical model to define a more sustainable strategy to fight against siltation in a more efficient and less costly way.

Are antifouling residues a matter of concern in the largest South American port?

In the present study, levels of booster biocides (diuron, Irgarol, chlorothalonil, dichlofluanid and DCOIT), butyltin compounds (TBT, DBT and MBT) and antifouling paint particles (APPs) were assessed in sediments of areas under the influence of the largest Latin American port, marinas, boat traffic and ship/boat maintenance facilities located within Santos-São Vicente Estuarine System (SSES). Contamination profile was directly related to local maritime activities, where sediments from the main navigation channel (MNC) presented low levels of antifouling residues while adjacent areas (AA), characterized by the presence of boats and boatyards, showed higher contamination considering all analyzed residues. Moreover, areas under the influence of fishing boats/yards presented relevant levels of butyltins (ΣBTs > 300 ng g−1) and APPs (>100 μg g−1), while marinas dominated by recreational boats showed higher booster biocides occurrence. Sites located nearby shipyards in the MNC and boatyards in the AA presented expressive amounts of APPs (>200 μg g−1). These APPs represent an important long-term source of biocides to the SSES. Thus, the profile of maritime activities in association to local oceanographic conditions drive the spatial distribution of antifouling residues within SESS, which in some case presented levels above sediment guidelines for TBT, DCOIT and diuron.

Guiana Dolphin (Sotalia guianensis) in the southern Gulf of Venezuela: Seasonal distribution, group size, and habitat use

Small cetaceans, such as the Guiana dolphin (Sotalia guianensis), do not migrate long distances to forage but use rather small areas subject to food source variations. Information on their distribution, behaviour, habitat use, and estimated population density play an important role in the identification of critical areas and regulating human activities within. Here we examine the seasonal variations, group size, and distribution of Guiana dolphin in the southern Gulf of Venezuela, to identify their critical habitats and thus aid mitigation planning. We used boat-based surveys with a follow-group protocol where observers monitor groups of animals for 30 min, from a distance of 20 to 30 m, gathering the following data: date, time observed, GPS position, estimated number of individuals, presence of calves, behavioural observations (when possible); and environmental parameters (sea-surface temperature, water transparency, salinity, sea state [Beaufort], and cloud cover). We found that Guiana dolphins did not use the studied area (6.33 km2) homogeneously but rather aggregated in north of Zapara Island’s retaining wall. The highest density of dolphins was between 301 and 573 individuals within 4.22 km2 approximately off north of Zapara Island, and the lowest (1 - 150 individuals) at the entrance of the main navigation channel. The group size was considerably larger in the wet season (mean ± SD = 6.4 ± 1.9 individuals, range = 1 to 80) than the dry season (2.2 ± 2.7 individuals, range = 1 to 27). The number of sightings differed among seasons (dry/wet), there were more sightings in the wet season (1.3414 ± 0.4389 groups, range = 1 to 5) than dry season (1.1233 ± 0.7418 groups, range = 1 to 5). Our data suggest this population might be highly adapted to local conditions and prey movements, and use the areas intensely year around, particularly during the wet season.

Input reduction and acceleration techniques in a morphodynamic modeling: A case study of Mumbai harbor

Thane creek, which houses two major commercial ports; Mumbai & Jawaharlal Nehru Ports face periodic siltation problems. The maintenance dredging, carried out to keep navigational channel navigable, incurs a high annual cost. In this study, an attempt has been made to simulate the annual morphological changes that occur within Mumbai port limits, using a process-based hydrodynamic and morphological model, developed using Delft3D numerical scheme. The tidal levels and currents of the numerical model are validated with in-situ measurements, carried out at three different locations near the main navigational channel. Adopting the concepts of the morphological tide and acceleration techniques, a total quantity of siltation of more than 3.98 Million m3 is estimated to be deposited annually in the main navigation channel, if no dredging is carried out. The modeling results also revealed that a siltation rate up to 1 m/year is observed in the harbor basin and entrance channel to the docks. It is demonstrated that the developed numerical model can qualitatively capture the morphological trends near Mumbai Port region.

Tide propagation and salinity distribution response to changes in water depth and channel network in the Guadalquivir River Estuary: An exploratory model approach

This study analyzes the management alternatives that are currently considered by public administrations in the Guadalquivir River Estuary, which is a well-mixed and rather channelized estuary in the southwest of Spain. A linearized multichannel exploratory model that operates at tidal and averaged scales is used. The model extends the previous developments for calculating the tidal variations of salinity and provides elevations, currents and salinity. The effects of the change in mean depth of the main navigation channel, the reconnection of a secondary tidal channel (Brazo del Oeste) and the recovery of a marsh in the lower part of the estuary are the three alternatives analyzed. The model outputs indicate that the channel deepening would produce an increase in the amplitudes of the elevations, tidal salinities, and tidal prisms, as well as the extent of the saline intrusion. Similar effects could be alternatively obtained with the reconnection of the secondary channel with suitable design parameters. The increase in tidal elevations due to channel deepening should therefore be considered in any dredging project, because lower sediment volumes need to be dredged to attain the projected water column height at high water. The recovery of marshes notably influences the tidal wave propagation when the connecting width with the navigation channel exceeds one hundred meters. Its most remarkable effect is to increase the tidal amplitudes and to reduce the tidal currents upstream the connection point in proportion to the degree of connectivity with the main channel. A combination of alternatives could potentially serve to mitigate the specific effects of individual alternatives. The effects of channel deepening on the amplitudes of the tidal elevation and the currents could be partially compensated for through the recovery of tidal marshes.

Transient nocturnal site fidelity in juvenile green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles on the shallow nearshore coral reefs of South Caicos, Turks and Caicos Islands

Opportunistic nocturnal catch-and-release turtle surveys were conducted on three nearshore, shallow coral reefs that fringe the main navigation channel to Cockburn Harbour, South Caicos, between 2005 and 2015. A total of 117 captures were made, representing 73 individual turtles (32 green, 41 hawksbill). Almost half of the green turtles were recaptured on at least one occasion, with a maximum time at liberty of 574 days (median = 94 days). Only 20% of hawksbill turtles were recaptured, with a maximum time at liberty of 587 days (median = 120 days). These data suggest that the study sites are utilised by a combination of transient visitors and short to medium-term resident turtles. However, no evidence of long-term nocturnal site fidelity was found. The size ranges observed in both species indicate that all turtles were immature, and the minimum sizes are consistent with previously reported settlement sizes from the region. Despite the lack of long-term fidelity, turtles were regularly encountered over the...

Damage Detection Based on Structural Responses Induced by Traffic Load: Methodology and Application

In consideration of the important role that bridges play in transportation system, their safety, durability and serviceability have always been deeply concerned. Recently, many long-span bridges have been instrumented with Structural Health Monitoring Systems (SHMS) to provide bridge engineers with the information needed for decisions-making in management and maintenance. However, efficient use of monitoring data remains a challenge confronted before engineers. Recently, methodologies based on monitoring data while robust to random disturbance and sensitive to damage have received worldwide attention. In this context, this study proposes an innovative damage detection methodology based on structural responses induced by traffic load. First, vehicle-induced strain responses are found to be separable from the strain induced by operational loads, owing to their unique characteristics. This is achieved by a detailed investigation on the relationship between strain measurements and operational loads including temperature, wind as well as vehicles based on long-term monitoring data. From the vehicular load and pertinent strain response, the strain influence line (SIL) can be further identified. As a structural signature, SIL can be used to provide a reasonable assessment of the bridge health condition at least in the vicinity of strain monitoring point. Two damage indexes are therefore derived from the identified SIL, which are promising for damage evaluation because they are: (a) capable of revealing structural deterioration; (b) immune to influences of environmental changes; (c) adaptable to the random characteristic exhibited by long-term monitoring data. Besides, the SIL identification procedure and its theoretical basis are elaborated to respectively handle the case where the vehicle load is available or not, which is also applicable to identify the influence line of other measurements such as stresses. The proposed damage methodology is applied to the cable-stayed bridge spanning the main navigation channel of Shanghai Yangtze River Bridge, and the result shows its effectiveness.

Aboveground Net Primary Productivity in a Riparian Wetland Following Restoration of Hydrology.

This research presents the initial results of the effects of hydrological restoration on forested wetlands in the Mississippi alluvial plain near Memphis, Tennessee. Measurements were carried out in a secondary channel, the Loosahatchie Chute, in which rock dikes were constructed in the 1960s to keep most flow in the main navigation channel. In 2008–2009, the dikes were notched to allow more flow into the secondary channel. Study sites were established based on relative distance downstream of the notched dikes. Additionally, a reference site was established north of the Loosahatchie Chute where the dikes remained unnotched. We compared various components of vegetation composition and productivity at sites in the riparian wetlands for two years. Salix nigra had the highest Importance Value at every site. Species with minor Importance Values were Celtis laevigata, Acer rubrum, and Plantanus occidentalis. Productivity increased more following the introduction of river water in affected sites compared to the reference. Aboveground net primary productivity was highest at the reference site (2926 ± 458.1 g·m−2·year−1), the intact site; however, there were greater increase at the sites in the Loosahatchie Chute, where measurements ranged from 1197.7 ± 160.0 g m−2·year−1·to 2874.2 ± 794.0 g·m−2·year−1. The site furthest from the notching was the most affected. Pulsed inputs into these wetlands may enhance forested wetland productivity. Continued monitoring will quantify impacts of restored channel hydrology along the Mississippi River.

Tramo desmontable del Puente de la Constitución de 1812 sobre la Bahía de Cádiz

A simply supported 150m long deck was built on the Cadiz Bay Bridge on the part that runs over the sea. It weighs about 4,000t, and has the possibility of being removed to make a way through the bridge, and allow the navigation of large floating structures that exceed the vertical clearance of 69.00m, which is what is available in the main navigation channel in the centre of the main span. This article describes the removable span and the special operations carried out for its installation. Within the complexity of these manoeuvres, the following can be highlighted: the transfer of the bridge deck from the dock to the floating barge, the positioning of the deck between piers, and the lifting operation to their final supports on the piers head.

Research on Jiepai Riverbed Evolution Law and its Evolution Trend Forecast in Middle Yangtze River

After Three Gorges reservoir impoundment, sediment transport and bed evolution characteristic had changed in the lower Yangtze River. Based on the observational data, sediment transport and bed evolution characteristic of Jiepai reach had been analyzed. The results showed that Jiepai reach evolution had a close relationship with income flow and sediment conditions. In recent years, the income flow and sediment conditions were propitious to the development of left slot of heart beach. It also had accelerated the low beach erosion in transition section and siltation in Xindijia. A 2-D mathematic model and river physical model had been used to forecast the river evolution trend. The results showed that the staggered beach would still not stay steady with the reservoir impoundment. The periodic time of evolution could become longer. Xiru bank beach in right bank of upper Jiepai reach would deposit and move downwards. The main stream discharge would centralize and increase. The left channel of heart reach would be eroded and the right one would dwindle gradually by the squeezing of the heart reach. The right branch channel, as the main navigation channel, would deposit and become shallow. The transition reach would move downwards at outlet of left channel. The riffle would present a staggered shape and left branch channel would dwindle gradually. The waterway transportation condition would get worse.

Asymptotic behavior of tidal damping in alluvial estuaries

Tidal wave propagation can be described analytically by a set of four implicit equations, i.e., the phase lag equation, the scaling equation, the damping equation, and the celerity equation. It is demonstrated that this system of equations has an asymptotic solution for an infinite channel, reflecting the balance between friction and channel convergence. Subsequently, explicit expressions for the tidal amplitude and velocity amplitude are derived, which are different from the generally assumed exponential damping equation that follows from linearizing the friction term. Analysis of the asymptotic behavior demonstrates that exponential damping of the tidal amplitude is only correct for a frictionless wave or an ideal estuary (no damping). However, in estuaries with modest damping (near ideal) it provides a reasonable approximation. In natural estuaries, there is generally a need to take account of local variability of, e.g., depth and friction, by subdividing the estuary into multiple reaches. This is illustrated with an example of the Scheldt estuary, which has been gradually deepened for navigation purpose over the last half century. The analytical model is used to study the effect of this deepening on the tidal dynamics in the main navigation channel, demonstrating that the navigation channel will become “overamplified” when it reaches a depth larger than the critical depth. In the case of overamplification, a further increase of the depth reduces the amplification until critical convergence (condition for a frictionless standing wave) is reached asymptotically. Finally, based on the ratio between the tidal amplitude at the seaward boundary and the asymptotic tidal amplitude, estuaries can be classified into damped, amplified, or ideal estuaries, which is illustrated with 23 real estuaries.

Does boat traffic cause displacement of fish in estuaries?

Estuaries are increasingly under threat from a variety of human impacts. Recreational and commercial boat traffic in urban areas may represent a significant disturbance to fish populations and have particularly adverse effects in spatially restricted systems such as estuaries. We examined the effects of passing boats on the abundance of different sized fish within the main navigation channel of an estuary using high resolution sonar (DIDSON). Both the smallest (100–300mm) and largest (>501mm) size classes had no change in their abundance following the passage of boats. However, a decrease in abundance of mid-sized fish (301–500mm) occurred following the passage of boats. This displacement may be attributed to a number of factors including noise, bubbles and the rapidly approaching object of the boat itself. In highly urbanised estuarine systems, regular displacement by boat traffic has the potential to have major negative population level effects on fish assemblages.

Effect of Migration Pathway on Travel Time and Survival of Acoustic‐Tagged Juvenile Salmonids in the Columbia River Estuary

AbstractWe applied acoustic telemetry methods to characterize migration pathways and estimate associated travel times and survival probabilities for juvenile Chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss migrating downstream through the Columbia River estuary (from river kilometer [rkm] 86 to rkm 8). Acoustic‐tagged fish were detected as migrating in the navigation channel and in off‐channel areas at each of the estuarine reaches we examined during May–August 2010. However, the majority of fish traveled in the main navigation channel from rkm 86 to rkm 37, at which point most fish left the river‐influenced navigation channel; crossed a broad, shallow tidal flat; and migrated the final 37 km in a secondary channel, which was characterized as having greater tidal transport than the navigation channel. The pathway used by acoustic‐tagged smolts to migrate through the estuary affected their rate of travel. In most reaches, navigation channel migrants traveled significantly faster than fish that migrated through off‐channel areas. Contrary to observations from previous studies, smolts that migrated through off‐channel areas at a slower rate did not experience lower survival than their cohorts that used the navigation channel. Although no significant differences in survival probability were observed between navigation channel migrants and off‐channel migrants, areas of high mortality were identified between rkm 37 and rkm 8. Dispersion of juvenile salmonids into multiple pathways during downstream migration can be beneficial in terms of increased expression of life history diversity and resiliency to environmental perturbations. Our results, which document juvenile salmon migration pathways and associated travel time and survival through a large estuary, can be used to focus future research and management activities in areas identified as having high mortality and therefore can be used to aid in the recovery of Endangered Species Act‐listed salmon populations.

New Runway on Huge Hybrid Structure: Tokyo/Haneda International Airport

The new runway (D runway) of the Tokyo/Haneda International Airport is located between the mouth of Tama River and the main navigation channel to Tokyo Port. One of the severe restrictions was that the new runway should not obstruct the flow of the lower reach of Tama River. In order to measure up to this requirement, a third of the new airfield was designed as an elevated jacket-type structure supported by steel pipe piles. The other two-third was designed so that it lies on the newly reclaimed land.The project was contracted between a joint ventured consortium and the Japanese government: Kanto Regional Development Bureau, Ministry of Land, Infrastructure, Transport, and Tourism. The consortium consists of 15 major Japanese companies: 6 general construction contractors, 3 steel companies, and 6 marine contractors. The contract was awarded for a combination of design and build. The agreement was concluded in March 2005 and the actual works got off to a start in April 2007.