| PAWSA:
METHODOLOGY
The PAWSA methodology developed by the USCG uses a generic model
of waterway risks. That model was developed from the work done by
the NDG in 1998. Risk factors identified by the NDG were put into
model form by Dr. Jack Harrold of George Washington University and
Dr. Jason Merrick of Virginia Commonwealth University. During the
course of more than four years of PAWSA workshops throughout the
United States, the model has been substantially revised to more
accurately reflect the nature of waterway risks being experienced.
Those revisions were made by Mr. Douglas Perkins, Program Manager
and Senior Facilitator at Potomac Management Group, Inc., in consultation
with the USCG Headquarters Office of Vessel Traffic Management.
The only “safety” related issues that have been deliberately
excluded from the model are those that relate to port, facility,
and vessel security. Those security-related issues are not covered
during a PAWSA because the workshop is unclassified and usually
open to the public whereas discussions of security issues quickly
delve into sensitive topics that should be treated as classified
information. Also, the USCG conducted a separate series of Port
Vulnerability / Security Assessments that looked specifically at
security issues.
Methodology Explanation
Recognizing the need for a formal risk assessment for one or more
waterways under his/her cognizance, a sponsor decides to hold a
PAWSA workshop. Using this Implementation Guide as the primary reference,
the sponsor arranges for a meeting location and selects a group
of waterway users and stakeholders from the local community to participate
in the workshop. During the workshop, participants discuss safety-related
issues relating to the waterway and then provide numerical inputs
to quantify those discussions. Those quantitative assessments are
organized into five logical segments, referred to as “books.”
An overview of each book is provided later in this chapter. As each
book is completed, the responses are entered into the PAWSA computer
software and, except for Book 1, aggregated results are then presented
to the participants. Participants have the opportunity to review
the results, discuss them with each other, and revise team answers
if there is a MAJOR disconnect between the qualitative discussion
and the quantitative output. Except for Books 1 and 2, participants
use the results from each preceding book as the springboard for
discussions during the subsequent phase of the process.
Waterway Risk Model
Since risk is defined as the product of the probability of a casualty
and its consequences, the Waterway Risk Model includes variables
dealing with both the causes of waterway casualties and their effects.
The six risk categories determined were:
- Vessel Conditions - the quality of vessels and their crews
that operate on a waterway.
- Traffic Conditions - the number of vessels that use a waterway
and their interactions.
- Navigational Conditions - the environmental conditions that
vessels must deal with in a waterway relating to wind, currents,
and weather.
- Waterway Conditions - the physical properties of the waterway
that affect how easy it is to maneuver a vessel.
- Immediate Consequences - the immediate impacts of a waterway
casualty: people can be injured or killed, petroleum and hazardous
materials can be spilled and require response resources, and the
marine transportation system can be disrupted.
- Subsequent Consequences - the subsequent effects of waterway
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.
The diagram below shows the final form of the six risk categories
and corresponding risk factors in the Waterway Risk Model.
Quantitative Assessments
Book 1: Team Expertise is used to capture
the expertise of each team relative to the other teams in the workshop.
The results from Book 1 are used to weight each team’s inputs
for all other books.
Book 2: Risk Factor Rating Scales develops
measurement scales for each risk factor by asking participants to
compare specified qualitative descriptions to each other in a pair-wise
manner. Those qualitative descriptions characterize the range of
possible conditions that affect risk in a waterway for that factor.
Book 3: Absolute Risk Levels is used
by the participants to determine where their waterway falls on the
risk scales developed in Book 2. What results is the risk level
for each factor, not taking into account any actions already implemented
to reduce risk in the waterway.
Book 4: Present Risk Levels is used
for two purposes. After the participants describe the risk mitigation
strategies that already exist to help reduce the risk level for
their waterway, Book 4 is used to evaluate the effectiveness of
those strategies in reducing the risk level for each factor in the
model. What results from that evaluation is the present risk level,
taking into account those existing mitigations. Second, they decide
whether the risk mitigation strategies already in place adequately
balance the resulting risk level…or not. If, for any given
risk factor, there is strong consensus among the participants that
existing mitigations DO adequately deal with those risks, then that
risk factor is dropped from further discussion.
Book 5: Intervention Effectiveness provides
the participants an opportunity to offer ideas about specific risk
mitigation actions that should be taken and to estimate how effective
those actions would be in further reducing risk levels. Participants
first discuss what else should be done ONLY for those risk factors
where the Book 4 results show that risk levels are NOT adequately
balanced with existing mitigations. Following the discussion, participants
decide which ideas have the most promise for each risk factor that
was discussed and what mitigation category the ideas relate to.
They write a short description of the action needed, that is, the
idea with the most promise, and then evaluate how much risk reduction
would result if that idea was implemented.
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