NCHRP 20-7
Proposed Research Needs Statement
AASHTO Subcommittee on Bridges and Structures
Chair, Gregg Fredrick, Wyoming Department of Transportation
June 2014
TITLE
Assessing Risk for Bridge Management
BACKGROUND / NEEDS STATEMENT
The “Moving Ahead for Progress in the 21st Century Act’’ or ‘‘MAP–21’’ requires that each
state develop a “risk-based asset management plan” and declares that “it is in the vital interest of
the United States … to use a data-driven, risk-based approach and cost-effective strategy for
systematic preventative maintenance, replacement, and rehabilitation of highway bridges and
tunnels to ensure safety and extended service life.” The legislation does not specify a method, or
performance measures, for considering risk. However, the language makes clear the desirability
of incorporating risk in a way that can reasonably be supported in a data-driven, cost-effective
process.
Risks of interest include those where an exogenous uncommon hazard, with random timing and
location, acts on one bridge or a small subset of bridges, causing a loss of access, seriously
degraded functionality for road users, unexpectedly rapid deterioration, or unexpectedly high
costs. For these types of risks, it may be possible to estimate hazard likelihood at the level of
geographic zones or structure categories, and vulnerability or resilience at the level of individual
assets. These approximate, probabilistic inputs may enable an agency with suitable tools to
quantify and manage risks in a data-driven cost-effective manner even if the exact risk for each
bridge can never be measured or the timing of event is not exactly known.
The hazards satisfying these criteria may include, but are not limited to, earthquakes and other
types of earth movement, hurricanes and tornadoes, floods and scour, fires, vehicular or vessel
collisions, fatigue, and advanced deterioration. These hazards have consequences that are beyond
the normal deterioration and functional deficiencies already assessed in bridge management
systems. The probability of each hazard, and the ability of each structure to resist the hazard, is
not always consistently and quantitatively assessed at the current state of the practice.
RESEARCH OBJECTIVE
The objective of this research is to synthesize the existing practices used to assess risk from
natural and man-made hazards; and synthesize the existing methods for post-event evaluation of
damage and rapid recovery strategies. The goal of this effort is to develop a framework and
recommendations for next steps, in order to develop a methodology for a data-driven assessment
of risks at the bridge and structure level, suitable for use in a bridge management system. The
framework should consider, to the extent feasible:
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The likelihood of a hazard and/or extreme event at the asset level or for groups of assets
where the data may be available;
The typical consequences of the hazard or event, to the bridge itself and to the public
(negative social, environmental and microeconomic impacts), including the network
effects of detours, traffic delays, economic downturn, and triggering of an environmental
catastrophe.
The probabilities of different levels of severity of the event and consequences.
Post-event evaluation of performance to improve bridge engineering methods on the
future and provide rapid recovery engineering strategies for use by bridge owners.
The investigation is not limited to existing data sources or tools, but the cost of new data
collection recommendation must be carefully examined, weighed and minimized where possible.
WORK TASKS
Tasks anticipated in this project include the following:
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Identify a set of hazards which are to be addressed using the methods to be developed in the
study. For each hazard, identify the types and severity of harm which might typically arise,
data sources, the likely range of risk magnitude, and the prognosis for quantifying the
likelihood and consequences.
Gather and synthesize the literature on existing engineering risk assessment and evaluation
for infrastructure assets from asset owners, private industry, past completed research, and
existing guidance. This effort is expected to include, but not limited to historical records of
various classes of extreme events and the effects to infrastructure assets. Information should
be gathered from both national and international sources.
Identify the gaps in existing guidance for pre-event risk assessment and post-event
engineering evaluation for bridge management decision making as well as rapid recovery
strategies specifically for bridges and structures.
Develop a preliminary framework and work plan for the development a comprehensive
AASHTO guideline for ensuring resilient bridges and structures, considering risk and rapid
recovery. This task should include recommending any additional research needed outside the
scope of this study. The framework should identify the types of qualitative and quantitative
data and information needed for effective decision making. The recommended framework
should consider the future incorporation into the function of existing bridge management software
such as AASHTOWare BrM.
URGENCY
In light of the increasing threats to the bridges and structures of the nation from extreme events,
as well as the known condition-based threats, bridge owners and other stakeholders including the
public, will be in a better position to understand the tradeoffs among risk, funding, and other
aspects of bridge and structures resiliency. Better decision making for bridges and structures
performance and reliability will be improved. Focused analytical studies are needed to develop
the approach to solving this on-going problem faced by all bridge owners.
FUNDING REQUESTED AND TIME REQUIRED
It is estimated that this research will take 12 months to complete and will require $100,000.
CONTACT PERSONS
Wahid Albert, P.E.
Acting Chair, T-1 Technical Committee for Bridge Security & Hazards
Director, Structures Design Bureau
New York Department of Transportation
50 Wolf Road
Albany, New York 12232
Phone: 518-457-4453
E-mail: walbert@dot.ny.gov
Matt Farrar, P.E.
Chair, T-18 Technical Committee for Bridge Management, Evaluation, and Rehabilitation
State Bridge Engineer
Idaho Department of Transportation
P.O. Box 7129
Boise, Idaho 83707-1129
Phone: 208-334-8538
E-mail: Matt.Farrar@idt.idaho.gov