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National Traffic Scorecard

Summary

To view the complete national and metropolitan summary, request the complete INRIX National Traffic Scorecard.

At a national level, the INRIX National Traffic Scorecard identifies overall statistics, compares regions and identifies the nation’s worst bottlenecks.

Overall Statistics
The methodology used to measure overall congestion and to establish metropolitan travel time index for each of the weekly 40 drive time hours enables the calculation of overall national congestion metrics, by hour, by morning and evening drive time, by day and overall. Overall, the nation’s drive time travel time index for 2007 was 1.13. This means that during drive time a random traveler on a random trip on the roads analyzed took on average 13% extra travel time than if there was no congestion. This represents an increase of 1.9% from 2006. The initial impacts of higher fuel prices, which averaged $2.85 for a gallon of regular gas in 2007, likely slowed the rate of growth of congestion as the year progressed.

A summary of the National Travel Time Index and “factoids” below lists the nation’s “best” and “worst” days, drive times, and hours relative to congestion.

National Travel Time Index and Drive Time Factoids National Travel Time Index

2007 National Travel Time Index = 1.133
1.9% increase in National TTI from 2006

National Factoids (Drive Times)

Worst Day: Friday
Worst Hour: Friday 5-6 PM
Worst Morning: Wed AM
Best Day: Monday
Best Commute: Friday AM
Best Hour: Friday 6-7 AM
Best Afternoon: Monday PM

The two National Travel Time charts below highlight the nation’s travel time index by day and by morning and evening drive times each day, along with each hour of each day of the week. While the results may be obvious and intuitive to some, the data can confirm just how much worse Friday evening drive time is than other drive times, for example. And importantly, if and when changes in patterns of travel occur at a national level that have material effects on congestion, they will likely appear as changes in future versions of these charts. With fuel prices soaring, possibly for the long-term and significant national and regional efforts to tackle the congestion issue, it is very possible that 2007 will be considered a baseline year – the year before the general long-term trend of more congestion, in more places, more hours of the day transitioned to a more nuanced macro-level pattern.

National Travel Times – The longest travel times are during PM commute hours on Thursday and Friday

National Travel Times – TTI Chart by all hours of each day of the week

Metropolitan Rankings
The rankings of the Top 100 Markets provide several different facts for each metropolitan area – facts that can be compared against the regions. Since there are numerous ways to sort the table, we have provided a variety of “top 10” lists.

Top 10 Rankings of Metropolitan Areas by Congestion and TTI Statistics

There are several conclusions to be drawn from this data:

Regions like southwest Connecticut, Honolulu and Austin may not rank high in terms of overall congestion, but it’s a safe bet that if you are on highways in these regions in peak hours, congestion is the norm.
Regions in Florida and other areas where housing slumps have been most evident, such as Las Vegas, have seen a decline in congestion in 2007 versus 2006. It is likely the list and extent of regions seeing declines will grow when 2008 data is analyzed.
Given the extent of congestion across America, it is going to take more than some drivers reducing their driving in response to high fuel prices to put a substantial dent into the problem. So far, the response by many has been to purchase more fuel efficient or alternative fuels vehicles rather than change driving habits. Fuel prices will need to be very high for a long time to affect choices in home and work locations to an extent to have a significant impact on congestion. Bottom line – even if congestion flattens or trends down in the near term, it’s not going away. High fuel prices will not end congestion.

Bottlenecks
Nearly 31,000 individual road segments were analyzed to determine the extent and amount of average congestion each had in 2007. More than 8000 segments contained at least one hour of the week were one can expect to travel at less than half the uncongested speed, with nearly 5000 segments having at least 5 hours of congestion. Remarkably, over 1000 segments experience 20 hours or more of congestion and the nation’s 100 worst bottlenecks were congested an average of 60 hours each week with the average travel speed less than 14 mph. The map below shows the geographic distribution of the nation’s 100 worst bottlenecks, shown in red overlaying the full set of analyzed roads in green.

National map of 1000 bottlenecks

The chart below shows the distribution of the nation’s 1000 worst bottlenecks by metropolitan area (CBSA).

When examining the bottlenecks on a national basis, several conclusions can be drawn:

Bottlenecks aren’t just a mega city issue. While a majority of bottlenecks are in Los Angeles, New York and Chicago, 42 of the 100 areas have at least one bottleneck in the top 1000.
With the worst 1000 bottlenecks congested 20 hours a week or more – basically 2 hours each peak period drive time – on average we can expect substantial congestion all across America. Add in an accident, bad weather or a special event and these locations go from bad to hopeless. There is no margin for error on a large portion of our major highway network.
Construction, while helping in the long run, can create long-term temporary bottlenecks. The third worst bottleneck in 2007 was in the San Francisco Bay Area (in Marin County) on I-580 as it approaches US 101, which is the site of a major interchange construction project. Most of the worst bottlenecks in Detroit in 2007 were associated with the Lodge Freeway reconstruction.
Several of the individual road segments identified as bottlenecks are connected to other segments also identified as bottlenecks – basically corridor bottlenecks. While these may be associated with an upstream interchange or geometric configuration issue, the length of these bottlenecks can be long.