Speed Harmonization on I-70 Sunday

The Colorado Department of Transportation (CDOT) and its law enforcement partners expect to implement RSH sometime between 11 a.m. and noon, when eastbound vehicle counts are expected to reach a minimum of 1,900 vehicles per hour.  At that time, a single police car will begin pacing vehicles, just west of the Eisenhower/Johnson Tunnel, and continue east to the bottom of Floyd Hill at speeds between 35 and 55 mph.

Law enforcement vehicles are expected to pace a new pace group or platoon about every five to seven minutes, with operations continuing along the 31-mile segment through mid- to late afternoon.

Police officers also will be manually metering the ramps coming from Loveland Pass and Empire Junction (U.S. 40) during RSH, allowing vehicles to better merge onto I-70.

If eastbound volumes exceed 2,500 vehicles per hour, RSH will be terminated for the day.  However, law enforcement will continue to meter the Loveland and Empire ramps, with other officers stationed at key locations for short-segment speed control and to provide assistance in case of accidents.

CDOT is reminding drivers to please comply with directions from the lead police vehicle, including NOT passing the police car pacing traffic.

“Last year’s travel time on the comparable Sunday {February 27, 2011} was 72 minutes, and our goal is to maintain that kind of reasonable travel time with speed harmonization Sunday,” said CDOT Regional Transportation Director Tony DeVito.  “The primary goal of this program is improving safety along the corridor and reducing accidents, which is a big contributor to traffic congestion.”

In addition to this Sunday’s operation, CDOT is planning on running RSH on two more Sundays – on March 4 and March 11 (see RSH Fact Sheet below).

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I-70 West Rolling Speed Harmonization (Pacing)

Fact Sheet

The Colorado Department of Transportation (CDOT), in coordination with its law enforcement partners,

is using a new method aimed at reducing congestion and accidents on eastbound Interstate 70, from the

west side of the Eisenhower Tunnel to the bottom of Floyd Hill. Known as Rolling Speed Harmonization

(RSH) or “Pacing”, this pilot program utilizes police vehicles during historic peak hours to pace traffic at

speeds, on average, of between 35 and 55 mph, depending upon weather conditions.

What is the purpose of RSH?

The purpose of RSH is to create more uniform vehicle speeds, helping to improve safety, reduce traffic

crashes and improve traffic flow on the corridor by delaying the onset of congestion. The concept is

similar to pouring rice into a funnel. If poured at a gradual rate, more grains pass through the funnel.

But if poured too quickly, it clogs. When traffic moves at a more uniform rate, more vehicles can pass

through, more efficiently. Differentials in vehicle speeds lead to a higher probability of accidents which,

in turn, substantially increases congestion. In some instances, RSH may not significantly improve travel

times from the previous year, however the hope is that it will create better predictability by reducing

accidents and other incidents caused by congestion so that motorist can better plan and know what to

expect for their travel time.

When will RSH occur?

CDOT may conduct RSH on Sundays or holidays through the 2012 ski season. The program may also be

implemented in mid-summer as traffic volumes indicate. RSH generally begins about 11 a.m. and

concludes by 5 p.m. however, the times are dependent upon traffic volumes. CDOT does not pace

vehicles when traffic is too light as it slows traffic unnecessarily. Conversely, when traffic is heavy, it

slows to speeds below the pacing speed on its own, so pacing is ineffective. The ideal time to pace traffic

is when traffic volumes are between 1900 – 2400 vehicles per hour, but this is approximate. If traffic

congestion increases to the point where speeds drop below 30 miles per hour or traffic backs up into

the Eisenhower Tunnel requiring CDOT to meter or clear traffic from the tunnel, pacing will conclude for

the day since it becomes ineffective.

Why does CDOT meter/clear traffic from the Eisenhower Tunnel?

Eastbound traffic is held or “metered” at the tunnel when vehicle volumes exceed the capacity of I-70 to

the point where it backs up into the tunnel. When back-ups occur, CDOT stops vehicles from entering

the tunnel, allowing traffic to clear, before releasing more traffic into the tunnel. This is not something

CDOT wants to do as it frustrates motorists and further slows traffic. It is only done for the safety of

motorists as a last resort since there are no roadway shoulders in the tunnel, CDOT needs to keep traffic

in the tunnel moving so that emergency service responders can access emergencies. When traffic is

stopped, they cannot get through or into the tunnel. Pacing is different than tunnel metering and

pacing is not connected to nor does it cause tunnel metering or the traffic stops in the tunnel.

How does RSH operate?

The operation generally begins between 11 a.m. and noon – when vehicle counts on eastbound I-70

reach between 1900 and 2,000 vehicles per hour. It continues through the late afternoon or

early evening, depending on traffic counts and road conditions. One police car serves as the pace

vehicle, with a new pace group or “platoon” leaving the Eisenhower Tunnel about every five to 10

minutes. In addition, key interchanges such as Loveland (US6) and Empire (US 40) have uniformed

officers that manually operate a ramp meter to allow traffic to merge into the gaps between the

platoons. After every RSH event, CDOT evaluates the data collected. Changes to the program are

continually occurring as new information is gathered each time it runs. For example, RSH is no longer

beginning in Silverthorne but instead will begin at the Eisenhower Tunnel approach. Additionally, CDOT

has refined when RSH goes into effect. Initially, it would begin when traffic volumes were lower but

instead CDOT is waiting until it builds to between 1900 and 2000 vehicles per hour, just before the time

when congestion is starting to build and the potential for accidents starts to increase. The messages

posted on the signs have been changed based on feedback from the public and the traffic control on the

ramps from US 6 and US 40 for vehicles merging into the RSH operation has also been improved in an

effort to make the program run more efficiently.

What is the cost of RSH?

CDOT supports the program by paying 24 off-duty officers, at an approximate cost of $12,000 for each

operation.

What do drivers need to know about driving during RSH?

When RSH is underway, it’s critical that drivers realize they won’t be able to jump ahead and drive any

faster. Groups of vehicles are slowed to leave a greater distance between each group. This is to allow

traffic to flow more smoothly. While a motorist may think the road is clear ahead and feel the urge to go

faster since they don’t see the other vehicles, the reality is they would just drive faster and catch up with

the next group, resulting in more traffic grouping together and backups to occur.

When pacing is in effect, CDOT suggests drivers should:

• Relax and be patient
• Avoid changing lanes unless it is absolutely critical due to debris or some other issue; both lanes should travel at the same speed, so “jockeying for position” is irrelevant
• It is fine to pass slow moving vehicles like semi trucks, to maintain the paced speed of your group
• Leave adequate space between your vehicle and the vehicle in front of you (ideally, one car length for every 10 mph; four to five car lengths at 40-50 mph)
• Keep your eyes up; don’t focus on the rear of the vehicle in front of you

CSP is reminding drivers to be courteous and safely follow and comply with the lead police vehicle.  Aggressive or unsafe drivers may be reported to the Colorado State Patrol by dialing *277 on your cell phone.

• RSH involves the regulation of traffic by law enforcement in an effort to ensure safe and speedy movement of traffic through the I-70 corridor.
• Vehicles traveling on I-70 during RSH may not overtake the lead law-enforcement vehicle at any time.
• Any vehicle that overtakes the lead law-enforcement vehicle will be contacted by a law enforcement officer.
• The contacting officer will take appropriate enforcement action against the driver of the overtaking vehicle.

Where is the biggest problem area?

I-70 west becomes clogged due to a number of factors. The most obvious is heavy traffic but the steep

grades, curves, weather, accidents, mixture of recreational and commercial vehicles and different driver

abilities/comfort levels all can affect traffic flow on the highway. Merging large numbers of vehicles

from US 40 into narrow sections of I-70 and trying to funnel the traffic through the Twin Tunnels creates

major backups. This area of interstate around the Twin Tunnels including the sharp curves east of the

tunnels experiences over 200 accidents/year and for whatever reason, drivers tend to slow down and

brake more often here. The result is a residual effect of stop and go traffic that can back up for miles.

The good news is CDOT has plans to expand the eastbound Twin Tunnel to add three lanes with

shoulders from the east Idaho Springs Interchange to Floyd Hill. This improvement will greatly ease

some of the congestion that occurs at this location. Construction will begin in the summer of 2013.

How did RSH come about?

Implementation of the pilot program began on Sunday, December 18, 2011. Its usage is not new in the

U.S. Similar speed control operations, often known as “Rolling Road Blocks,” have been effectively

utilized in other states, such as Florida, Nebraska and Virginia, to safely move vehicles through heavy

traffic areas or construction zones. Minneapolis uses overhead electronic speed limits to slow speeds to

appropriate levels for the congestion. However, it has never been used for such a long segment of

highway in a mountain corridor such as I-70 west.

Is RSH working?

CDOT has been working hard to find a low-cost solution to improve the weekend traffic congestion on I-

70. While this program will not solve all of the I-70 traffic problems, particularly when traffic volumes

are extremely heavy, every indication is that it can be used to improve the flow of traffic on days that

could otherwise result in unpredictable and significant travel delays. It’s important to note that every

weekend is different. Traffic crashes, weather and other incidents all can affect travel times and that is

why CDOT is collecting data each time the program runs.

Data collected from previous operations indicates that the program is promising but does have its

limitations. The more times the operation runs, the more data CDOT can collect to better evaluate the

positives and the negatives of the program. There is an indication that RSH has created more uniform

vehicle speeds and has reduced traffic crashes and improved traffic flow as well as reduced the number

of times traffic was stopped and cleared or metered at the Eisenhower Tunnel.

CDOT is continuing to acquire data to evaluate and modify the program following each day it is implemented, seeking any necessary improvements in the operation.