This page is still under construction.
Freeway and Arterial System of Transportation (FAST) is contracted to NDOT to operate
the freeway system in Las Vegas Metropolitan area. This is the monthly/Quarterly operation
summary for NDOT.
Frequently Asked Questions (FAQs)
Q: How are the seasons defined?
A: Since traffic volumes and performance are directly related to school being in
session or holidays, we divide a year into six "seasons":
- Beginning of Calendar Year: from first day of school after holidays
to a mid-march Friday.
- Spring: from mid-march to mid-April and captures traffic volume
and pattern change attributable to local and visitor spring breaks and warmer weather.
- Early Summer: picks up then and goes to the Friday in the week
that school lets out.
- Summer: goes to the first day of school in late August.
- Fall: goes to the Monday of thanksgiving week.
- Holiday: from thanksgiving week through the entire holiday season
until the New Year's first day of school.
There are very noticeable changes in traffic volumes when school is out. So we compare
each sub-corridor's performance season over season.
Q: What is the reliability score?
A: The reliability score is a measure of the type and extent of congestion. The
attachment has more details. A score of 0 means no congestion events occurred during
the season. A score slightly below 200 suggests predictable recurring congestion
on weekdays and minimal other congestion events. Scores in the 300s / 400s (or high
200s) suggest a combination of recurring congestion plus extreme congestion events,
crashes that cause congestion outside of the peak periods, and congestion caused
by work zones. Detailed information regarding how the scores are calcuated can be
found here.
Q: What do the color arrows mean?
A: A dark green arrow means that a season, when compared with the performance from
the previous year, has improved reliability scores, fewer ‘extreme’ congestion events
in the peak period, higher daily volume, and a reduced number of crashes per day.
A light green arrow means that, typically, all but one of the measures show improvement.
Yellow and orange arrows suggest that performance improvements are balanced by performance
degradation or the performance is degrading from the prior year’s season.
Q: What are the benefits of using ITS and applying operation strategies?
A: From the reports, you may find how the performance changes season over season
and year over year. The thinking, in terms of ITS benefits, is "Can we absorb increases
in volume without having the overall performance of the freeway degrade?" ITS investments
and programs should contribute to safe and efficient traffic flow, our performance
report quantify the extent to which this occurs. For examples, I-15 Northbound at
Sahara performance has improved because of enhanced patrolling by NHP and FSP. I-15
Northbound further to the south is showing strong performance following the completion
of Design-Build South.
Q: What does "Friday daily volume" column mean?
A: For each year and season, a daily Friday volume is selected to represent the season and corridor.
Q: What doesn "Crash per day info" column mean?
A: This is a summary of all crashes managed by FAST. We gather data on how quickly the crash vehicles are moved out of the travel lanes and deduct crashes that are cleared in 10 minutes or less from the total.
Q: What does the "percent change" column mean?
A: The percent change columns compare the performance of, for example, beginning year 2013 with beginning year 2012, and we assign an appropriate arrow based on the comparison.
Performance Reliability Score
Scores are calculated by doing the following:
- Each day earns a score based on peak period and off peak period performance.
- For the peak period, performance is assigned to one of three categories: no or minimal
congestion, normal recurring congestion, or significant congestion.
- For the off peak period, all congestion caused by non‐peak incidents or construction
activity is noted.
- For the peak period portion of a score, no or minimal congestion days are multiplied
by 0, normal recurring congestion days are multiplied by 2, and significant congestion
days are multiplied by 6.
- For the off‐peak period portion of the score, each event (incident or congestion
due to construction) is multiplied by 3.
The scores displayed on slides are computed by doing the following:
- The numerator is the sum of weighted scores for all days in a season (see the season
defination in the FAQs ).
- The denominator is the number of days in the season.
- Do the math and multiply by 100 to get rid of nasty decimal points and you get your
score!