Beginning the Dialogue - Report on SGR - Federal Transit ...

Defining and Measuring SGR
value) that do not exceed <strong>the</strong>ir expected useful life or
(ii) based on engineering assessments of <strong>the</strong>
proportion of assets that are in “good working order”.
The chart below presents an example of this
measure, showing <strong>the</strong> proportion of U.S. transit
assets, by type, that are less than <strong>the</strong>ir expected
useful life. The chart is based on asset data from <strong>the</strong>
Federal Transit Administrations’ (FTA) Transit
Economic Requirements Model (TERM).
Percent of U.S. Transit Assets in SGR (Estimate)
Power
Guideway Structures
Trackwork
Elevators / Escalators
Rail (Yards & Shops)
Stati ons
Communications
Bus Facilities
Revenue Vehi cl es
Signals
0% 20% 40% 60% 80% 100%
While easy to develop and easy to explain to
decision-makers, percent of assets in SGR provides
no information on <strong>the</strong> condition of assets currently in
SGR. For example, are most assets in excellent
shape or will a significant proportion of assets
currently in SGR require rehabilitation or replacement
in <strong>the</strong> near future? Percent of assets in SGR cannot
shed light on <strong>the</strong>se questions.
Percent of Service Life Remaining: Distributions of
percent of service life remaining show <strong>the</strong> proportions
of transit assets at different stages during <strong>the</strong>ir
service life cycle based on <strong>the</strong>ir expected useful life.
In <strong>the</strong> example below, track work assets from a
sample of U.S. rail operators are segmented into
quarter life groupings (for trackwork within its useful
life) and an additional grouping for trackwork that has
exceeded its expected service life. This presentation
provides more information on <strong>the</strong> overall condition of
an asset grouping, as compared to <strong>the</strong> percent of
assets in SGR example presented above. This
measure can be applied to any grouping of agency
20
assets, ranging from <strong>the</strong> age distribution for a specific
subsystem (e.g., rail switches) to age distribution of
all agency assets system-wide.
Percent of Trackwork by Service Life Remaining
(1/4 Lives) Service life
24% to 0% of
service life,
13%
49% to 25%
of service
life,
10%
exceeded
18%
100% to 75%
of service life
31%
74% to 50%
of service
life,
28%
Note that infrastructure managers in o<strong>the</strong>r industries
often report only <strong>the</strong> proportion of assets that
currently exceed <strong>the</strong>ir useful life. This is sometimes
called a “facilities condition index” and equal to <strong>the</strong>
following:
Facilities Condition Index = Value of Assets Exceeding Useful Life
Value of all Assets
This measure has also been used to establish a
desired SGR target within some industries (e.g., no
more than 2% of assets exceed <strong>the</strong>ir useful life). Note
that <strong>the</strong> percent of assets that currently exceed <strong>the</strong>ir
useful life is <strong>the</strong> exact opposite of <strong>the</strong> proportion of
assets in SGR measure.
Asset Condition Ratings: While <strong>the</strong> percent of
service life age distributions presented above
provides a good understanding of <strong>the</strong> proportions of
assets in varying conditions, <strong>the</strong> practice of using
quarter-life age groupings is arbitrary. Specifically,
<strong>the</strong>se age groupings may not provide a good
representation of <strong>the</strong> differing phases of asset
conditions an asset will experience throughout <strong>the</strong> full
life cycle. To address this issue, many transit
agencies, state DOTs and engineering firms utilize
four- or five-point condition rating scales to assess
<strong>the</strong> condition of capital assets. An example of this