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Is Colorado's I-70 Winter Ski Traffic Getting Worse? It Depends

Colorado Department of Transportation
Weekend traffic heading west on I-70, near Floyd Hill, in 2010.

Hordes of skiers headed into Colorado's mountains over President's Day weekend. For most of them, it's a pretty good bet they experienced traffic congestion on I-70.

As Colorado's population grows, are these delays getting worse? It's a question worth asking. To learn the answer, KUNC analyzed five years of winter weekend travel time data from the Colorado Department of Transportation. The findings may surprise you.

Even without the funding difficultiesfacing CDOT, the I-70 corridor is a challenge. There's two 11,000-foot mountain passes. There's extreme winter weather.

Then, there's you — and thousands of skiers and snowboarders like you — trundling up the hill each weekend. That creates "urban traffic volume" on a corridor that wasn't built with that in mind, said CDOT's Ryan Rice, who directs transportation systems management and operations for the department.

That volume is directly related to delays, said Rice. Take President's Day 2015 for an example. Lots of people took advantage of the extra day off to head into the mountains. Which translated into massive wait times on eastbound I-70 on the way back to the Front Range. 

According to CDOT data for that day, the stretch of I-70 running from Dillon to C-470 had a peak travel time of 142 minutes.  In normal conditions, it's supposed to take 56 minutes. That's nearly an hour and a half delay.

Is this the new normal? According to CDOT, traffic volume on the I-70 corridor is steadily up. But are delays increasing as well? When KUNC looked at five years of winter weekend travel times, we found that while delays on I-70 certainly do not show any sign of lessening, they also are not getting dramatically worse.  

What Kind Of Data Did KUNC Collect?

First, a bit of background on the data. We requested travel times for each hour of each winter weekend travel day (although some days lack data for certain hours or occasionally the entire day).

The data covers weekends only. Westbound data includes Fridays and Saturdays, and eastbound includes Saturdays, Sundays, and winter holidays.

Each winter runs from Dec. 1 through Mar. 31, effectively the end of ski season. The data is shown on a 24-hour clock, with travel times starting at midnight (0:00) and going to 11 p.m. (23:00).


As the charts indicate, it's clear long delays have been a part of I-70 weekend traffic at least going back to 2010 (and probably longer). There does not appear to be a trend in delays getting better or worse, at least over the past five years.

But delays do seem like they are becoming frustratingly common. Take a look at the yellow on the charts. Yellow shading indicates delays longer than the expected travel time and red indicates even more severe delays.

The winter of 2010-11 has significant areas of delays, noted in yellow and red. Things get a bit better in 2011-2012 and 2012-2013, but in the 2013-2014 and 2014-2015 winters, more and more hours during winter weekends turn yellow.

If this continues to hold in the future, it means if you travel I-70 on a winter weekend, it's likely you'll experience a delay of at least 20 minutes. Rice, of CDOT, said delays of 30 minutes were more or less expected on the corridor during most ski weekends.


What Is CDOT Doing To Help?

Ryan Rice said the agency has implemented various measures to improve the corridor as traffic volumes continue to increase. Most the measures have been incremental and have not required infrastructure improvements — one example is changes to where cars are metered entering the Eisenhower tunnel eastbound. Another includes messages encouraging drivers to shift travel times later - although that's had a minimal effect, said Rice.

The most recent effort is the transformation of an 8-mile shoulder lane in the eastbound direction into a third express traffic lane. That's eased one choke point, leading to "dramatic improvements" in eastbound traffic on that particular stretch, Rice said.

But more remain. Eight miles is only a small stretch of the busy corridor. Rice pointed to the Eisenhower and Johnson tunnel as another key "plug" in the I-70 drain. Without a tunnel rebuild, it will continue to be a source of congestion and delays. 

The stopgap measures CDOT has undertaken to date may be one reason there isn't a clear negative trend on the corridor. But there is not a positive trend either, and as the data shows, there are plenty of days with very significant delays.

Rice and CDOT acknowledged that the corridor needs infrastructure improvements to fit the growing number of vehicles. Yet when asked if CDOT has a long term plan for improving infrastructure like the tunnel, or adding more lanes to the corridor, the answer was no.

"Right now there is no concrete plan that says CDOT is going to go in, in the year 2025, and spend, you know, $3 billion and make I-70 from Vail to Golden three lanes in each direction," said Rice.

In the meantime, CDOT seems focused on short-term fixes coupled with faith that technology will play a big role in a congestion solution. Rice envisioned a future where smart car technology allows agencies to shrink lanes from 12 feet to seven feet wide and eliminate shoulders. That would allow the transportation department to add lanes without widening the road.

Smart cars aside, at some point, though, the corridor will need to be expanded, at least in strategic places, Rice acknowledged. Without a plan, though, it's certain the solution will be a long time coming.

Stephanie Paige Ogburn has been reporting from Colorado for more than five years, primarily from the Western Slope.
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