Chapter 5 - Appendix F

Waterway Risk Model Explanation

Waterway Risk Model Explanation

Risk is defined as the probability of an unwanted event
[TIMES]{.underline} the impact of that event. The 1997 National Dialogue
Group developed an initial list of risk categories and factors that
relate both to the causes or probability of marine accidents
[AND]{.underline} to the consequences or impact of those events. That
list, which has been modified over time, was made into a Waterway Risk
Model. The figure shown below provides a basic overview of the waterway
risk model categories as they relate to the risk equation. The six risk
categories, and their respective risk factors are listed and defined on
the following pages.

**Vessel Conditions** -- the quality of vessels and their crews that
operate on a waterway; each waterway has what are considered to be high
risk vessels, such as old vessels, vessels with poor safety records,
vessels registered in certain foreign countries, vessels belonging to
financially strapped owners, vessels with inexperienced crews /
operators, etc. When assessing risk, the following items should be
considered (as appropriate) for each risk factor: Maintenance, age,
flag, class society, ownership, inspection record, casualty history,
language barriers, fatigue related issues, and local area knowledge.

-   *Deep Draft Vessel Quality* -- the quality of the deep draft vessel
    itself and the proficiency and quality of the crew. Deep draft
    vessels are those large, ocean-going vessels, often in international
    trade, that usually are constrained by their draft to use dredged
    channels where such channels exist. Deep draft vessels include such
    things as: oil tankers, container ships, break bulk cargo ships, and
    cruise liners.

-   *Shallow Draft Vessel Quality* -- the quality of the shallow draft
    vessel itself and the proficiency and quality of the crew. Shallow
    draft vessels include all other commercial craft EXCEPT commercial
    fishing vessels. Examples include tugs / towboats, offshore supply
    vessels, charter fishing boats, small passenger vessels (inspected
    under 46 CFR Subchapters T and K) such as dinner cruises and
    ferries.

-   *Commercial Fishing Vessel Quality* -- the quality of the commercial
    fishing vessel itself and the proficiency and quality of the crew.
    These vessels are included because they are not required to undergo
    annual vessel inspections nor are the crewmembers required to hold
    USCG licenses; therefore, there may be a greater potential for
    increased incidents involving commercial fishing vessels.

-   *Small Craft Quality* -- the quality of the small craft vessel
    itself and the proficiency and operating knowledge of the
    individuals who operate them. Small craft include all manner of
    boats used for noncommercial purposes (i.e., pleasure craft or craft
    used by indigenous people for transportation or subsistence
    fishing). They can be powered by an engine, the wind, or human
    exertion. Examples include yachts, personal watercraft (a.k.a., jet
    skis), and kayaks. Besides local knowledge, understanding of the
    rules of the road and inebriation also should be considered for this
    risk factor.

**Traffic Conditions** -- the number of vessels that use a waterway and
their interactions. Volume equals the absolute numbers on a waterway.

-   *Volume of Commercial Traffic* -- the amount of commercial vessel
    traffic using the waterway (i.e., the more vessels there are on the
    water, the more likely that there will be a marine casualty). Deep
    draft and shallow draft commercial vessels as well as commercial
    fishing vessels are included in this risk factor. Shoreside
    infrastructure is also addressed in this risk factor (i.e., can it
    handle the volume of commercial traffic within the waterway).

-   *Volume of Small Craft Traffic* -- the amount of noncommercial
    vessel traffic using the waterway. The volume may vary depending on
    the time of day, the day of the week, the season of the year, or
    during a major marine event.

-   *Traffic Mix* -- the interaction between vessels or boats of
    different sizes using the same waterway and their maneuvering
    characteristics. Conflicts occur as risk increases with each type of
    vessel's different maneuvering characteristics and actions that are
    often unpredictable (e.g. commercial mariners / recreational
    mariners using deep draft vessels / shallow draft vessels within the
    same waterway).

-   *Congestion* -- the ability of the waterway to handle the volume /
    density of traffic. Risk increases when a large number of vessels
    uses a small geographic area for an extended period or time. Risk
    also increases substantially when you get a larger than normal
    number of vessels together for a short time (e.g., fishing
    tournament or short season commercial fishery).

**Navigational Conditions** -- the environmental conditions that vessels
must deal with in a waterway relating to wind, currents, and weather.

-   *Winds --* the difficulty in maneuvering vessels resulting from
    increased and/or unpredictable winds, particularly if the wind is
    from abeam.

-   *Water Movement* -- the difficulty in maneuvering vessels caused by
    water movement (river / tidal currents) flow and speed, often
    affected by seasonal variations and sustained winds. Tide rips and
    whirlpools can be created by strong currents and affect the
    maneuverability of smaller vessels. The frequency of occurrence and
    the location of the strongest currents in the waterway are critical
    considerations (e.g., if current speed can exceed vessel speed,
    timing is critical when transiting the area).

-   *Visibility Restrictions* -- the natural conditions that may prevent
    a mariner from seeing other vessels, aids to navigation, or
    landmarks, such as fog, severe rain squalls, etc.

-   *Obstructions* -- floating objects in the water that impede safe
    navigation and/or damage a vessel, such as ice, debris, fishing
    nets, etc.

**Waterway Conditions** -- the physical properties of the waterway that
affect how easy it is to maneuver a vessel.

-   *Visibility Impediments* -- the man-made objects (e.g., moored
    ships, condominiums, background lighting) or geographic formations
    (e.g., headlands, islands) that prevent a mariner from seeing aids
    to navigation or other vessels.

-   *Dimensions* -- the room available for two vessels to pass each
    other within the waterway. How big is the waterway compared to the
    vessels using it? In some areas, one-way traffic results from
    extremely narrow channels.

-   *Bottom Type* -- the material on the waterway bottom or just outside
    the channel, such as hard rock, mud, coral, etc. How much damage
    occurs to a vessel if it runs aground?

-   *Configuration* -- the arrangement of a waterway including elements
    such as waterway bends, multiple/converging channels, and
    perpendicular traffic flow.

**Immediate Consequences** -- the instantaneous impacts of a vessel
casualty (i.e., what happens right after a collision, allision, or
grounding?). How well is the local community prepared to handle the
immediate consequences resulting from a vessel casualty?

-   *Personnel Injuries* -- the maximum number of expected casualties.
    People can be injured, killed, or need to be rescued---the more
    people on the water, the more rescue personnel / efforts needed.

-   *Petroleum Discharge* -- the largest petroleum spill in the most
    probably worst-case scenario---the more cargo there is, the higher
    the risk to waterway safety and the more response personnel /
    efforts needed.

-   *Hazardous Materials Release --* the largest chemical or hazardous
    material spill in the most probably worst-case scenario---the more
    cargo there is, the higher the risk to waterway safety and the more
    response personnel / efforts needed. It is necessary to
    differentiate between products shipped in bulk and those shipped in
    containers because containers provides a high degree of protection
    to the cargo such that a large, instantaneous release is far less
    likely to occur; therefore, the potential consequences will be far
    lower.

-   *Mobility* -- the infrastructure that is critical to the Marine
    Transportation System within the waterway (i.e., the significant
    structures upon which moving people and cargo through the marine
    transportation system depend). The waterway can be blocked and the
    shoreside Marine Transportation System can be disrupted, ultimately
    causing greater problems moving cargo through a port---both on the
    water and ashore.

**Subsequent Consequences** -- the longer-term effects of vessel
casualties that are felt hours, days, months, and even years afterwards,
such as shoreside facility shut-downs, loss of employment, destruction
of fishing areas, decrease or extinction of species, degradation of
subsistence living uses, and contamination of drinking or cooling water
supplies.

-   *Health and Safety* -- the potential consequences to the community
    that lives or works on or near the waterway. The more people who
    live or work in close proximity to a waterway, the greater the risk.

-   *Environmental* -- the risks to wetlands and endangered species and
    how sensitive people are to the quality of their environment. The
    more sensitive, the more people will expect in terms of both
    preparedness and response effectiveness for any marine

accident that threatens environmental quality.

-   *Aquatic Resources* -- water dwelling life forms harvested for
    commercial or recreational reasons. Timing of a marine casualty
    could affect how serious the consequences would be (i.e., some
    species are only in the waterway at certain times of the year).

-   *Economic* -- the extent of the impact if a particular waterway is
    closed for some period of time. Most waterway communities are
    dependent on unrestrained use of waterways for their economic
    well-being. For some waterways, the economic impacts would only be
    felt by those who directly use that waterway for their livelihoods.
    But for other waterways those economic impacts could have national
    repercussions.