NPHQ > About Us > Measurement
Graphs
Measurement Graphs
NPHQ uses eight (8) graphs prepared and periodically updated by
FHWA as tools to measure the improvement in quality and customer
service of highways in the United States. Click the items below
for the graphs showing trends for:
If you have any questions, please contact Mr. Ken Stoneman, Chairman
of the NPHQ Measurements Subcommittee, at kenneth.l.stoneman@odot.state.or.us
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| Graph courtesy of Federal Highway Administration |
- To accurately represent fatalities, they need to relate to
total vehicle miles traveled.
- Total fatalities have leveled off over the past three years.
However, when compared to miles driven, there is a reduction
in the rate.
- Better quality roads, improved shoulders, and additional
lanes, coupled with seat belt laws, law enforcement, air bags
and other safety measures, all contribute to the reduction of
fatalities per VMT.
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| Graph courtesy of Federal Highway Administration |
- Total work zone fatalities need to be relative to the number
of miles of work zones. Since this information does not exist,
fatalities were compared to total dollars spent, which relates
indirectly to the number and miles of work zones.
- Total work zone fatalities, standing alone, have dropped
21% over the past four years from 833 to 658.
- Other information, such as time in work zones or injuries,
is not available.
- The reason for the drop (corridors, traffic control, speed
enforcement) need to be explored and shared.
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| Graph courtesy of Federal Highway Administration |
- Smoothness rated according to the International Roughness
Index: IRI<95 inches/mile
- All NHS roads are monitored annually by the respective state
Department of Transportation.
- Data is compiled by the Federal Highway Administration.
- A difference may exist between the public's perception of
smoothness and the scientific data on smoothness.
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| Graph courtesy of Federal Highway Administration |
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| Graph courtesy of Federal Highway Administration |
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| Graph courtesy of Federal Highway Administration |
- Congestion exists when vehicle miles traveled exceeds the design
capacity of the available lanes.
- The five-year trend shows VMT has increased 12.2% while lane
miles have increased 1.7%.
- Current congestion exists because, since 1970, VMT has increased
130%; and additional lane miles have increased 5%.
- Improving traffic flow may reduce congestion where adding lanes
is not an option.
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| Graph courtesy of Federal Highway Administration |
FHWA is now using the Normalized Congested Travel Index, and
the Normalized Travel Rate Index to measure and track congestion.
Together, these new indicators should reflect changing travel
conditions more effectively.
The Normalized Congested Travel Index addresses the following
question - "How much did congested peak period travel increase
compared to increases in regular travel?" The measure includes
two components: 1) The primary piece reflects changes in the percent
of time that a particular roadway is congested during peak periods.
For example, a 50% value for Interstate 'XYZ' indicates that half
of the travel during peak periods occurs under congested conditions.
When looked at in aggregate, an increase would indicate that more
of the travel on our highway system is being regularly affected
by congestion. 2) The second peice consider VMT growth. To ensure
that accurate travel condition metrics are generated, the new
measure must be compared against change in travel in a given base
year. This process normalizes the measure and gives us a point
of comparison.
Positive Results: If results of 1.01 or higher, from a baseline
of 1.0 in 1996, are achieved, the results will indicate that progress
has been made and congested travel is either decreasing or is
increasing at a slower rate than total travel.
Negative Results: If the actual value falls below 1.0, congested
travel is increasing at a faster rate than the total travel.
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| Graph courtesy of Federal Highway Administration |
The normalized Travel Rate Index addresses the following question
- "How much longer does it take to travel during congested
conditions?" The Normalized TRI measure includes two components:
1) The primary piece is the change in the TRI. The TRI tells us
how long a specific trip in a corridor or metropolitan area takes
compared to the same trip in uncongested conditions. 2) Similar
to the Normalized Congested Travel measure, the second piece considers
changes in VMT against a given base year. This process normalizes
the metic and provides a point of comparison.
Positive Results: If results of 1.01 or higher, from the 1996
baseline of 1.0, then travel time index is decreasing or increasing
at a rate slower than total travel.
Negative Results: If the results fall below 1.0, the travel time
index is increasing at a faster rate than total travel.
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