< Travel Time Reliability Reference Manual

Below are graphs and data for an 6-lane urban freeway (I-43/I-894 near Milwaukee) and 4-lane inter-regional (I-94 west of Eau Claire). All data comes from the NPMRDS data set in January 2012.

6-lane urban freeway (4.35 miles) Free flow travel time is based on the 70th percentile travel time

Reliability IndexValue
TTI1.01
BI0.26
OPT94.90
PTI1.27
TTI801.02
MI1.40


Travel Time in minutes
Mean4.58
Free Flow4.55
95th %5.76
80th %4.65
97.5th %6.47


4-lane interregional freeway (20.18 miles) Free flow travel time is based on speed limit of 65mph

Reliability IndexValue
TTI1.03
BI0.06
OPT98.40
PTI1.09
TTI801.038
MI1.150


Travel Time in minutes
Mean19.26
Free Flow18.63
95th %20.38
80th %19.33
97.5th %21.42

The 3-D graphs below show travel times by day and by hour for each corridor. Visually, one can see the better reliability of the inter-regional corridor over the urban. Blank areas represent points where real-time data did not exist along the entire corridor.

Travel Times for 6-lane Urban Freeway in January 2012

Travel Times for 4-lane Inter-regional Freeway in January 2012

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Travel Time Reliability Reference Manual

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