RPT-46-GS-11 Methods For Detection Of Floating Debris

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RR111Methods for Detection of Floating DebrisSummary Report based on the study by Oxford CreativityReport No: RPT-46-GS-11Report Version: 1.0Report Version Date: 12/06/2011GLA/DfT Confidential

RPT-46-GS-11GLA confidentialLead AuthorReviewerApproved for ReleaseGeorge ShawMartin BransbyNick WardPrincipal Dev EngineerR&RNAV ManagerResearch DirectorGSMBNWPlease make comments in this box:Version Date: 12 June 2011Page 2 of 22Version: 1.0

RPT-46-GS-11GLA confidentialExecutive SummaryUnder the new Wreck Convention, the GLAs may in future take on a statutory duty to detectand deal with floating debris that poses a hazard to shipping. Such debris includescontainers, timber, wooden pallets and other cargo lost from ships. This preliminary studyconsiders methods by which this duty can be performed in a cost effective manner,demonstrating due diligence. The results of the study provide evidence of GLApreparedness to take on such a role.Detecting and locating floating debris presents an additional task somewhat different fromthe existing marking of wrecks. This study, undertaken by Oxford Creativity on behalf ofR&RNAV, has identified and evaluated methods of reliably, efficiently and affordablydetecting a variety of floating debris throughout UK waters. Floating debris is by its naturevery diverse, in terms of its size, spatial distribution and constituent materials. Much of thedebris will float low in the water, possibly submerging intermittently, which presents asignificant challenge for systems deployed for detection.As an initial study, the objective is to identify candidate technologies, sensors, systems andmethods of reliable detection of floating debris. It presents a broad categorisation of thesurveillance task and analyses potential solutions as combinations of sensors and platformsfrom which they can be deployed. At this stage, until the details of the new WreckConvention are defined, it principally signposts the direction for further investigation ofsolutions. The approach of the study has been to review available sensor technologies andtheir applicability for debris detection from fixed observation stations and mobile platforms:among others, these include satellite imagery, airborne radar and lidar, shipboard optical,FLIR and sonar sensing.Since 1996, there have been approximately 10,000 accidents reported to the MarineAccident Investigation Board (MAIB). Of these, some 200 have been caused by floating orsubmerged debris. Although cargo containers are the highest profile of types of floatingdebris, the frequency of occurrence of confirmed collisions with cargo containers is very lowand wooden debris is much more likely to be the cause of damage and incident.The task of detecting floating debris is a massive challenge given the extent of the seasurface area to be surveyed and the relatively small size of the component debris to bedetected – less than 1m2 in roughly 60,000 km2 for UK territorial waters (12 n.m. limit),increasing to 750,000 km2 for the 200 n.m. limit of the UK Exclusive Economic Zone (EEZ).In the worst case, detection of debris could result in high costs for many of the technologiesinvestigated. For mobile sensors, the costs are driven primarily by the high cost of thedeployment of the sensor platform – such as aircraft or satellite – that is able to cover thesea surface area with sufficient frequency to have an impact. In the case of aircraft, the costmay be in the order of 5 for each square kilometre of sea served or half a million pounds foreach scan of UK territorial waters.It is concluded that families of detection systems, optimised for the category of surveillance,may be necessary to detect floating debris of many different types. Three principalsurveillance categories have been identified, each with their associated potential detectionsolutions: wide area surveillance using high resolution satellite imagery and side-lookingairborne radar (SLAR); narrow area surveillance using fixed shore-based radar stations in areas such asport approaches; local pinpoint search from a ship at sea using optical, Forward Looking Infra Red(FLIR), radar and sonar sensors, possibly deployed from the wreck-marking vessel.Version Date: 12 June 2011Page 3 of 22Version: 1.0

RPT-46-GS-11GLA confidentialDocument DisclaimerThis document is uncontrolled when removed from iManage (either electronic or printed)Document InformationClientGLAsProject TitleDetection of Floating DebrisDeliverable NumberD224 (2010/11)Report TitleMethods for Detection of Floating Debris (Summary Report)Report IdentifierRPT-46-GS-11Report Version1.0Report Version Date12 June 2011Lead AuthorsGeorge ShawLead Author’s ContactInformationG ShawGLA Research and RadionavigationTrinity House, The Quay, Harwich, Essex, CO12 3JW, UK,T: 44 1908 216291M: 44 7766 510578E: George.Shaw@gla-rrnav.orgW: www.gla-rrnav.orgContributing Author(s)iManage LocationR&RNAV DeliverableDeliverable D224 of the R&RNAV 2010/11 work programmeWork Packagereference5.2.1.3 (Detection of Floating Debris)Deliverable TitleDetection of Floating Debris – Summary ReportCirculation1. Project Files (hard copy)2. GLA Chief Executives3. R&RNAV RNAV distribution listVersion Date: 12 June 2011Page 4 of 22Version: 1.0

RPT-46-GS-11GLA confidentialContents1234Introduction . 71.1Background . 71.2Scope of Study . 71.3Definition of ‘Wreck’. 7Scoping the Detection Problem. 82.1Search Area . 82.2Types of Floating Debris . 82.3Likelihood of Incident with Floating Containers . 82.4Cost Consideration for Surveillance . 9Survey of Sensors / Detector Systems . 103.1Overall performance parameters of detectors . 103.2Passive Detector Systems . 103.3Active Detector Systems . 113.4Indirect Detector Systems . 12Sensor Platforms. 134.1Detection by Scanning Sensors on Fixed Platforms . 134.2Detection by Scanning Sensors on Mobile Platforms . 144.3Detection by Satellite Sensors . 145Conclusions. 156Recommendations . 17AAppendix: Distribution of UK Floating Debris Incidents. 18BAppendix: Indirect Detector Systems . 21CAppendix: Glossary . 22List of TablesTable 1: Summary of Passive Sensors . 11Table 2: Summary of Active Sensors . 12Table 3: Number and Coverage of Fixed Coastal Scanning Sensors . 13Table 4: Families of Detection Systems by Category of Surveillance . 16Table 5: Summary of Indirect Sensors . 21Version Date: 12 June 2011Page 5 of 22Version: 1.0

RPT-46-GS-11GLA confidentialList of FiguresFigure 1: Frequency Distribution of Debris-Related Incidents . 18Figure 2: Geographic Distribution of Reported Floating Debris Incidents . 19Figure 3: Reported Incidents in the English Channel Region . 20Reference DocumentsRD1A Study into Methods of Detecting Floating Debris, Oxford Creativity Report,Final Version, August 2010, iManage document 23665RD2TRIZ innovative problem solving method, based on patent analysis, detailed athttp://www.triz.co.uk/?gclid ace.org/raw/content/en/documentsreports/plastic ocean report.pdf.RD4“Marine Litter A Global Challenge” www.unep.org/pdf/UNEP Marine LitterA Global challenge.pdfRD5BAE Systems (Insyte) HF shore-based Surface Wave Radar for wide areamaritime ps/public/documents/bae publication/bae insyte data hfswr.pdfRD6GeoEye satellite imagery service: http://www.geoeye.com/CorpSite/RD7A software system using radar environment survey marketed by Norwegiancompany Vissim: http://www.vissim.no/RD8US company Sicom radar system http://www.sicomsystems.com/.Version Date: 12 June 2011Page 6 of 22Version: 1.0

RPT-46-GS-11GLA confidential1 Introduction1.1BackgroundUnder the new Wreck Convention, the GLA may take responsibility for the detection,marking and removal of floating debris, including containers and other cargo lost from ships.The GLAs may assume a statutory duty to reduce the risk to shipping that is posed by awide variety of floating debris, so this preliminary study seeks ways in which this duty can beperformed in a cost effective manner, demonstrating due diligence.The study has been undertaken in response to the proposal of the Nairobi ‘InternationalConvention On The Removal Of Wrecks 2007’ that was adopted at the InternationalMaritime Organisation (IMO) International Conference on the Removal of Wrecks held inNairobi in 2007. The Convention provides a set of uniform international rules aimed atensuring the prompt and effective removal of wrecks. The new convention will not come intoforce until ratified by at least ten IMO member states (which at the time of writing has not yetoccurred).1.2Scope of StudyThis report summarises the results of a study [RD1] (undertaken by Oxford Creativity usingthe TRIZ [RD2] innovative problem solving methodology on behalf of R&RNAV) to evaluatemethods of detecting floating debris. The distribution, frequency and type of incidents areinvestigated, and the methodology for considering detector systems is described. Thedetector system survey outlines a number of candidate sensors and fixed or mobileplatforms for their deployment, associated with different categories of surveillance. Familiesof detection systems are evaluated for area surveillance and survey in the vicinity of a ship.While questioning the cost effectiveness of any possible debris detection system, this reportidentifies an approach comprising three levels of survey: wide area surveillance at sea,narrow area (coastal) surveillance and pinpoint searches from the GLAs’ own vessels.1.3Definition of ‘Wreck’The significance of the new Wreck Convention lies in the agreed definitions of ‘MaritimeCasualty’ and ‘Wreck’, as contained in Article 1 of the wreck convention:“Maritime casualty” means a collision of ships, stranding or other incident of navigation, orother occurrence on board a ship or external to it, resulting in material damage or imminentthreat of material damage to a ship or its cargo.“Wreck”, following upon a maritime casualty, means:(a) a sunken or stranded ship; or(b) any part of a sunken or stranded ship, including any object that is or has been onboard such a ship; or(c) any object that is lost at sea from a ship and that is stranded, sunken or adrift atsea; or(d) a ship that is about, or may reasonably be expected, to sink or to strand, whereeffective measures to assist the ship or any property in danger are not already beingtaken.Thus the definition of a wreck, and the scope of the consequent obligations placed uponorganisations responsible for wrecks or their consequences, is extended to include any partof a ship, or any other object lost at sea from a ship. The GLAs are well acquainted withmethods of detecting conventional wrecks, but detecting and locating floating debrispresents an additional and somewhat different task: hence the need for this study.Version Date: 12 June 2011Page 7 of 22Version: 1.0

RPT-46-GS-11GLA confidential2 Scoping the Detection Problem2.1Search AreaThe study has considered the floating debris problem within the waters of the UK ExclusiveEconomic Zone (EEZ); however, most of the results will be relevant in a worldwide context.Key areas for survey are the English Channel and the entrance and exit to the Irish Sea, butareas of the UK territorial waters and contiguous zone will be important where sea room islimited by offshore installations. The prime search area is roughly 50,000 km2 for theChannel and Irish Sea and 120,000km2 for the combined territorial and contiguous zone 24n.m. limit). The total search area of the UK EEZ would be 750,000km2. These figuresgovern the cost of surveillance of the various sea areas.2.2Types of Floating DebrisFor the purpose of evaluating candidate detection systems, two very different classes offloating debris have been considered: 20ft metallic shipping containers lost overboard, floating 77% submerged below thesea surface, intermittently covered by waves. (See Appendix A of [RD1] forspecifications of common types of containers. Appendix B of [RD1] discusses theflotation of lost containers at sea, in particular, their depth of submergence.) Timber (e.g. sawn wood or lumber) or wooden pallets, with a typical piece of debrisbeing only 1m2 of wood floating 2cm above and 20cm below the water. Timber, beingnon-metallic, is less responsive to some active detection techniques (such as radar).There is anecdotal evidence that containers containing buoyant cargoes can remain afloatfor considerable periods of time. A perfectly sealed 20ft container, loaded to the maximumpermitted weight, would float with 77% of the container below the sea surface. Depending onsea state, a container may thus be submerged below the sea surface for significantproportions of time, intermittently breaking the surface. With only a small freeboard (that partof the container’s bulk visible above the sea surface), visual or electronic detection is likely tobe difficult. This is a major factor contributing to the hazard of floating containers, especiallyat night or in low visibility, or during poor weather or high sea state.2.3Likelihood of Incident with Floating ContainersIt is instructive to consider the likelihood of containers being found in global waters, and therisk of a ship’s incident (colliding or experiencing a near-miss) with a container. Assumingthe total number of containers globally lost at sea per annum is 10,000 and a floating periodof one week (before the container either sinks or is removed), the expected number ofcontainers afloat globally at any time is 200.As the total navigable area of the world is 1.8*108 km2, the expected occurrence of floatingcontainers is approximately one container per one million km2 of sea surface. During avoyage, a cargo ship covers a nominal swathe of sea area roughly 50m x 500km (width xdistance travelled) or 25km2 per day. Making a simple assumption that the spatialdistribution of ships and lost containers is statistically uniform, the likelihood of an incidentwith a container is 1 in 40,000 (or 2.5*10-5) for each individual vessel per day. Maritimesafety considerations are generally based on an ‘acceptable probability’ of incidents of theorder of 10-5 per 3 hours (or 8*10-5 per day) per vessel. Hence, based on simpleassumptions, the expected global rate of incidents with containers is ‘acceptable’.However, further assuming that the size of the global SOLAS fleet is 20,000 vessels, thelikelihood that a vessel somewhere in the world will experience a container incident duringVersion Date: 12 June 2011Page 8 of 22Version: 1.0

RPT-46-GS-11GLA confidentialany one day is roughly 40%, and globally a container incident can be expected every twodays.Clearly the risk of an incident with a container is increased in denser shipping areas such asUK and ROI waters. An indication of this higher risk can be estimated for 75,000 km2 of theEnglish Channel and its approaches. Based on an estimate of about 400 ships in the area atany time (consistent with one ship passing through the Dover Straits every 4 minutes onaverage), the ratio of shipping density in the Channel to the global average density can beestimated at approximately 50. If a reasonable assumption is made that the density of lostcontainers in this area is only 12 times their global density (i.e. container density increasesby only 25% of the increase in shipping density in the Channel, accounting for the prevailingsea conditions being relatively benign), then just one floating container (on average) willpose a hazard to shipping in the Channel at any time. The likelihood of a container incidentin the Channel in any 24 hour period for each individual ship is therefore approximately 1 in3000 (0.033%, or a probability of 3.3*10-4). Over all 400 ships in the area, the likelihood thata vessel somewhere in the Channel will experience a container incident in any one day is12% and the expected time interval between container incidents in the Channel isapproximately 8 days.The Channel has some 10 to 100 (or more) pieces of debris per square kilometre (visiblefrom a ship) as reported in [RD3]. This gives a broad estimate of more than 1,000,000pieces of debris that might be visible with the naked eye from ships in the Channel.Appendix B contains an analysis of UK incidents related to floating debris, based on datafrom the Marine Accident Investigation Branch (MAIB).The United Nations Environmental Programme report [RD4] lists the types of marine litterencountered in studies around the world. The two most common types of large hard litterare wooden pallets and oil drums, both of which could cause damage to light vessels. Othercommon types of large litter are tarpaulins and floating ropes which can cause propellerdamage and be particularly dangerous close to shore or high traffic areas.2.4Cost Consideration for SurveillanceIf a typical flotation period for a container is only one week, then an effective detectionservice may need to provide a frequency of surveillance with a significantly shorter period,perhaps daily. A detailed risk assessment would be necessary to determine the requirementfor the surveillance frequency of any sea area, commensurate with the risk posed tomariners.However, as an indication of the possible costs of surveillance, consider the survey of the20,000 km2 of the English Channel on a daily basis. Assuming that surveillance ispracticable 24 hours per day, the average rate of area surveyed would need to exceed 800km2 per hour. This rate is likely to be achieved only by a mobile survey platform, such as anaircraft or satellite. These surveillance options are discussed further in section 4, for whichthe

Channel and Irish Sea and 120,000km2 for the combined territorial and contiguous zone 24 n.m. limit). The total search area of the UK EEZ would be 750,000km2. These figures govern the cost of surveillance of the various sea areas. 2.2 Types of Floating Debris For the purpose of evaluating c

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