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Overall Resources Available
for Transportation
Allocation
Highway Transit Rail Air Port Across
Modes
Allocation
Interstate System Other NHS Other Systems Across
Networks
Scope of
IHS Plan
Allocation
Roads Structures Safety Features Facilities Across
Assets
Figure 2.3. Example IHS resource allocation process in context.
decisions are often made with a shorter time horizon and often Risk Management
target existing (not projected) performance and condition issues.
The basic strategy recommended for integrating decision Ideally, any decision-making process should take risk
making for IHS assets with the broader decision-making scope into account. As the risks faced in management of the IHS
presented here is for each IHS owner to develop an Interstate are significant and the potential consequences of risk such
Asset Management Plan on a periodic basis. The plan should as failure of an IHS link can be staggering, incorporating
summarize conditions of IHS assets, establish performance risk assessment into a framework for managing the IHS is
measures for those assets considering available funds, and de- a topic of particular importance. Risk management is of
scribe the plan for future investments in the IHS. The plan, importance for managing any transportation system, but is
once developed, will help support the agency's ongoing re- of particular importance for the IHS because of the magni-
source allocation process for its IHS network across invest- tude of the consequences to society when and if risks to the
ment categories and decision-making horizons. It also should system are realized.
provide consistent information about the system that can be Tragic events such as the Northridge Earthquake of 1994
shared among the many agencies managing the network. A starkly illustrate the importance of this topic. When this
recommended outline for an Interstate Asset Management earthquake struck the Los Angeles area on January 17, 1994,
Plan is presented in Section 2.4. it caused extensive damage to Los Angeles freeways, includ-
ing the collapse of two bridges on Interstate 10 between
downtown Los Angeles and Santa Monica, the collapse of
2.3 Focus Areas for Interstate the Interstate 5/Antelope Valley Freeway interchange and a
Asset Management closure of a portion of State Route 118 in the Simi Valley.
Previous work on transportation asset management is The transportation-related economic impact of the event has
readily transferable to the present study, but developing an been estimated to be over $1.5 billion (3). Similarly tragic
asset management framework tailored to the IHS requires ex- consequences arose from the collapse of the Mianus River
tending previous work on transportation asset management, Bridge on Interstate 95 in Connecticut in 1982, from the
focusing in on selected areas. These include: damage caused along the Gulf Coast by Hurricane Katrina
in 2005 and by Hurricane Ike in 2008, and from the 2007
· Defining how to better incorporate assessment of the risks collapse of the Interstate 35W bridge over the Mississippi
of system failure into an asset management framework; River in Minneapolis.
· Providing guidance for handling all IHS assets, particularly Transportation agencies that own and operate the IHS are
assets besides pavements and bridges; and well aware of the risks they face as they deliver a service--
· Recommending a set of measures tailored for use in re- providing a transportation network--to the public. Further,
porting and facilitating discussion of IHS performance individual agencies have performed in an exemplary fashion in
both within an agency, to system users, industry partners, responding to events such as those described above. However,
and nationally. the existing tools and approaches developed for asset manage-
ment are of limited value for managing risk. While asset man-
The following sections describe each of these areas further. agement principles are not inconsistent with the concept of risk
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assessment, it is true that this has not been an area of significant apply to all assets, modes, and investment categories. A concern
focus in many asset management implementation efforts. Fur- voiced in the Guide and in other work on transportation asset
ther, while significant work has been performed on risk assess- management is that agencies should make investment decisions
ment for transportation in recent years, there is little guidance across assets, modes, and investment categories, rather than
available on how to integrate a risk management approach with concentrating decision making within narrowly defined "silos,"
an agency's asset management-related processes. with each silo focusing on a specific asset and/or type of invest-
Chapter 3 of this document describes an approach to risk ment. In spite of this concern, the reality is that significant at-
assessment for IHS assets that integrates best practices in risk tention has been devoted to developing systems and approaches
management with the concepts of transportation asset man- for handling two asset types--pavements and bridges--while
agement. The approach is focused on the risks of system failure. the data, tools, and approaches for other asset types are typically
In the context of this report, system failure refers to any con- rudimentary by comparison. This is not an accidental develop-
dition that results in closure of an IHS link to travel for some ment: pavements and bridges necessarily consume the greatest
period of time, as a result of unintentional hazards, inten- portion of agencies' preservation expenditures, and the data,
tional threats, natural hazards, or substandard performance. A tools, and processes have evolved based on this reality.
scenario-based approach is presented for quantifying the risks The current study, with its focus on developing a practical
to a set of IHS assets, including their likelihood, consequences approach for managing all of an agency's assets, but for only
if realized, and available mitigation approaches. Ideally, the the most critical portion of the agency's network, forces the
quantitative approach presented in this section would be used question of how an IHS owner should go about managing "all
to perform a comprehensive risk assessment. However, the of those other assets" listed in Table 2.1. Chapter 4 details the
section describes an alternative threshold approach that an data and tools typically available for each asset category and
agency can use where sufficient data and resources are lacking type, focusing on assets other than pavements and bridges
to support the recommended approach. The outcome of ap- that have been the subject of much of the attention in trans-
plying the scenario-based approach is a recommended allo- portation asset management in the past. With regard to other
cation of resources to mitigating risk based on a determination assets beside pavement and bridges, the guidance can be sum-
of how an agency can best minimize the expected economic marized as follows:
losses from the risks it perceives to its IHS assets.
If a risk can be managed through other systems and processes · IHS owners should collect inventory and inspection data
without employing the scenario-based approach detailed in for IHS pavements and bridges consistent with both Fed-
Chapter 3, the risk is referred to as a "programmatic" risk. In eral reporting requirements and the requirements of pave-
the case of performance risks, such as substandard design, ment and bridge management systems, and they should
construction defects, materials defects, and unexpected traffic use these systems to manage pavements and bridges.
volumes, these risks are best addressed through existing preser- · IHS owners should collect inventory and inspection data for
vation programs, such as pavement preservation and bridge all of their IHS structures, including those listed in Table 2.1.
preservation programs. In theory, asset management systems Tools and techniques employed for managing bridges should
should help manage these risks, but the reality is that there are be employed for managing other IHS structures besides
gaps that need to be filled to improve systematic capabilities bridges. The basic logic for this recommendation is simple:
for handling programmatic risk. Chapter 4 describes the exist- structures can fail catastrophically, and in so doing cause
ing tools available for managing IHS assets and identifies gaps system failure (closure of an IHS link for some period).
that should be addressed in their capabilities. · IHS owners should report conditions on other assets, in-
cluding safety features, based on the degree the assets are
"functioning as intended." A maintenance level of service
Guidance for the Comprehensive Set
or remaining service life approach is recommended for
of IHS Assets
budgeted future investment needs for these assets.
Each of the individual segments of the IHS is composed of
a number of distinct types of infrastructure assets. Table 2.1
Performance Measure Reporting
details the infrastructure assets associated with the IHS,
for IHS Assets
organized by asset category. Even though rights-of-way,
equipment, and people may be viewed as assets using a broader A cornerstone of transportation asset management is its
definition of the term, they are not included in the table because emphasis on using quality information to make performance-
they are not part of the built infrastructure. based decisions. Encouraging a performance-based approach
AASHTO's Asset Management Guide emphasizes that the is consistent with best practices followed in other industries
transportation asset management principles and processes and the direction of many state transportation departments
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Table 2.1. IHS infrastructure assets.
Asset Category Asset Type
Roads Pavement
Shoulders
Structures Bridges
Tunnels
Culverts/drainage structures
Noise barrier walls
Retaining walls
Overhead sign structures
High mast light poles
Safety Features Pavement markings/delineators
Lighting
Guardrails
Median barriers
Impact attenuators
Signs
Surveillance and monitoring equipment
Signal and control equipment
Facilities Rest areas
Toll plazas
Weigh stations
Maintenance depots
Pump houses
Communication facilities
(DOT). The AASHTO Guide discusses performance measures plan to collect and report the full set of comprehensive mea-
for asset management at high level, and NCHRP Report 551 (4) sures in the future.
covers this topic in detail. Chapter 5 details the recommended performance manage-
This study adopts the terminology and basic approach for ment approach for IHS assets. Table 2.2 summarizes the
describing performance measures and targets introduced in recommended core measures.
NCHRP Report 551. The approach described in Volume 2 of With regard to the Environment category, it is clear that
that report, summarized in Figure 2.4, has been employed to this is an area of great importance, but there are few environ-
develop a set of performance measures for use in reporting mental measures that can be both localized to the IHS, and
IHS conditions in an Interstate Asset Management Plan. used to support the asset management process. Also, there is
With this approach, performance measures are used to mon- little consistency from one IHS owner to another concerning
itor progress towards policy goals and objectives, reflect asset how environmental data are collected and reported. Thus,
conditions, provide a long-term view of asset life cycles, and rather than recommending a specific set of measures as in the
track program delivery. Performance targets are specific per- other categories, for the Environment category this report
formance measure values an IHS owner plans to achieve. recommends a report card approach, whereby an IHS owner
These are set based on consideration of past trends, predicted establishes a set of environmental milestones and reports
future performance, agency funding levels, and other factors. whether they are achieving them on a pass/fail basis. These
In developing the set of measures, the research team made milestones may include measures of air quality, wetlands
a distinction between measures that every IHS owner should restoration, provision of mitigation features such as wildlife
be in a position to report today, labeled "core" measures, and crossings and fish passages, and an indication of the extent
additional measures that would be desirable to report for IHS the IHS owner is satisfying its environmental commitments.
assets if an agency has sufficient data and resources, labeled Chapter 5 lists a number of additional comprehensive
"comprehensive" measures. Ideally, every IHS owner would measures. The comprehensive set includes measures of asset
report the core measures described here, at a minimum, and performance for each of the categories listed in Table 2.1.
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Identify
Identify Performance
Performance Measures
Measures
Inventory Define Identify Candidate Assess and Select
Assess
Existing Selection Measures/Adjustments Measures for Further
Gaps
Measures Criteria to Existing Measures Design and Implementation
Integrate
Integrate Performance
Performance Measures
Measures into
into the
the Organization
Organization
Tailor Design Consistent Identify Design Document
Engage
Measures Measures Across Improvements to Communication Definitions and
Stakeholders
to Decisions Program Areas Data and Tools Devices Procedures
Establish
Establish Performance
Performance Targets
Targets
Analyze
Define Establish
Select Develop Consider Resource Consider
Contexts Targets and
Scope Long-Term Funding Allocation Policy and
and Time Track
of Measures Goals Availability Scenarios Public Input
Horizons Progress
for Targets and Trade-offs
Source: NCHRP Report 551.
Figure 2.4. Setting performance measures and targets.
Table 2.2. Recommended core IHS asset management
performance measures.
Category Asset Type Measure Type Measure
Preservation Pavement Structural Adequacy Present Serviceability Rating (PSR)
or an agency's pavement condition
index
Ride Quality International Roughness Index (IRI)
Bridges Structural Deficiency Percent classified as Structurally
Deficient (SD), weighted by deck
area
Signs Asset Performance Percent functioning as intended
Pavement Markings/ Asset Performance Percent functioning as intended
Delineators
Guardrails Asset Performance Percent functioning as intended
Mobility Travel Time Travel time index
Delay Delay per vehicle in hours
Safety Crash Rate Number of crashes expressed as
number per year and per million
vehicle miles traveled (VMT)
Fatality Rate Number of fatalities expressed as
number per year and per VMT
Environment Agency-specific report Pass/fail indication for each measure
card of environmental
milestones
