Their first step was ranking the metropolitan areas with the worst rush-hour congestion. The order is based on the peak hour Travel Time Index (TTI) for the metropolitan area each highway is in. TTI is a measure of how much longer it takes to complete a road journey during peak congestion hours compared to free-flow hours. (Peak hours are defined as 6 a.m. to 10 a.m., and 3 p.m. to 7 p.m.) Speeds during non-peak hours are used by INRIX to establish this free-flow baseline.
After determining the 75 worst metro areas, they then found the worst highway in each, defined as the most hours of bottleneck congestion, as reported by INRIX. The rankings then provide a still deeper look—at the most congested bottleneck segment for the worst highway in each area.
You can read the full list HERE, displayed as a single page. Utah rated two entries on the list:
#54, Highway 201, Salt Lake City
Weekly hours of bottleneck congestion: 10
Worst bottleneck: Eastbound, S 7200 W
Length of worst bottleneck: 1.52 mi
Weekly hours of congestion on worst bottleneck: 10
Speed of worst bottleneck when congested: 21.3 mph
Commuter Buzz: "It looks like the road is wet from here, and you never can tell if it's wet or if it's dry," Trooper Mary Kaye Lucas told KSL5 of a November blizzard that blanketed Highway 201. "The road has little grooves in it, and the water will get in between those grooves and make the road a lot more treacherous than it initially appears."
#72, I-15, Ogden, UT
Weekly hours of bottleneck congestion: 45
Worst bottleneck: Northbound, Center St/Exit 317
Length of worst bottleneck: .19 mi
Weekly hours of congestion on worst bottleneck: 11
Speed of worst bottleneck when congested: 20.8 mph
Commuter Buzz: “It's just like a movie. You see everything in your car flowing with you, with the car. It's pretty cool, but I don't wish it upon anyone," says motorist Cody Graham. "Whatever you do, if you're hitting ice, don't hit the brakes. That's I learned tonight."
Not included on the list was the commute from the east side of Utah Lake to the west side through Lehi. This weakens the case for a proposed Utah Lake Bridge, which, at best, is clearly too far ahead of its time. The Pioneer Crossing project is expected to solve much of that problem.
Utah Commuter Link provides camera pictures to help commuters identify and avoid hotspots whenever possible.
INRIX has also produced more detailed national traffic scorecards for the top 100 markets nationwide. Their mid-year scorecard for 2009, which ranks Salt Lake as the 50th most congested market in the nation, and Ogden-Clearfield as number 94, is available HERE.