Thursday, May 14, 2015

New ramp meters designed to help I-5 traffic move more smoothly between Lacey and Tacoma

By Doug Adamson

Congestion relief slated for I-5 in Thurston and Pierce Counties
I-5 congestion in Thurston and Pierce counties at times can be rough. The situation certainly doesn’t help people going to work, families trying to reach soccer practice, or business operators moving freight and goods. We are continuing efforts to help alleviate time-wasting traffic. In addition to building some big capacity-improving projects on Interstate 5 through Tacoma, another major effort soon will launch between Lakewood and Lacey.

Lakewood, JBLM, DuPont shrouded ramp meters to be unveiled
Drivers may have noticed new ramp meters being installed on I-5 ramps in Lakewood, Joint Base Lewis-McChord, and DuPont. Those ramp meters are set to come online as early as Monday, May 18. These proven tools are part of a group of improvements designed to help reduce congestion on this stretch of I-5. While long term solutions are being explored, we are working to make the most of the lanes that are out there now.

Crews will activate new ramp meters at these interchanges near Joint Base
Lewis-McChord where traffic routinely slows to a crawl during the morning
and afternoon commute.
Ramp meters: A key tool
As an I-5 driver, you’ve no doubt seen it a thousand times. You slow down or even stop to let a group of merging vehicles onto the freeway. The car in front of you and the 10 cars behind you do the same, resulting in braking, occasional collisions and added congestion to the highway. During peak commute hours, that slowdown gets compounded by the heavy traffic volumes. Picture what happens when you temporarily dam a creek. Water backs up. The water changes course, slows down and spreads out because of the obstacle.

Reduce the flow of traffic to a trickle
This predicament is created as traffic lights near interchanges move large numbers of vehicles at the same time onto an already-packed highway. Ramp meters are a big part of the solution – they create a momentary pause for each vehicle merging onto the highway. Instead of a large number of vehicles merging at the same time, congestion is eased when vehicles merge at a gradual and controlled rate. The controlled rate helps prevent highway drivers from hitting their brakes, and helps reduce collisions at the merge point.

How they work
Vehicle-sensing technology is installed at the ramps and along the highway lanes. Data from those sensors are sent to computers that crunch numbers to determine the best balance for traffic flow on both the ramps and lanes. The ramp meters automatically activate when they are needed, and at the ideal rate for the real-time traffic conditions. Ramp drivers participate in that process by stopping at the white stop bar at the meter. Their vehicle triggers a sensor that tells the meter it needs to turn green. Once the green light goes on, the driver is free to proceed. Some ramps allow more than one vehicle to proceed on the green light; signs at each ramp will tell drivers how the specific ramp meter works.
The new ramp meters, traffic cameras, and variable-message and travel-time
signs are part of a federally funded project specifically designed to help alleviate
congestion through this corridor by installing intelligent transportation systems
(ITS) tools to better manage traffic.
When they operate
Ramp meters generally operate during morning and afternoon weekday commutes, but they can also be activated any time there is a disruption in traffic flow like what’s seen with a blocking collision.

Sometimes the meters operate when highway traffic at the ramp appears to be moving just fine. The ramp meters are integrated and can look at highway volumes far upstream of drivers. Their goal is to sense when traffic volumes start getting heavier, and to help prevent backups before they begin.

Team approach
We are working collaboratively with leaders from the Cities of Lakewood, Lacey and DuPont, JBLM, Pierce and Thurston counties, transportation planning organizations, and others to tackle traffic congestion on I-5 in the south Sound. As an example, the City of Lakewood landed a $5.7 million grant to improve access to Madigan Army Medical Center by making improvements to the Berkeley Street overpass (Freedom Bridge). That construction is scheduled to begin in 2015.

The other side of the coin
While ramp meters help traffic flow on highways, the system can affect traffic on city streets. We understand the short delays merging onto the highway may cause driver frustration. It gets back to that balance – a short wait at a ramp meter gives more dividends to drivers by smoothing out the highway commute.

This proven technology has been used across the country for decades and in the greater Seattle area for over 20 years. Meters aren’t even new to Pierce County. They have been operating for the last few years on State Route 16 in Tacoma, and they’ve been used extensively in King and Snohomish counties. Here’s the takeaway: Ramp meters are a cost-effective and efficient way to boost freeway efficiency.

We need your help
We believe we can’t build our way of out congestion. The massive expense alone makes huge expansion unsustainable. At the same time, the state’s high quality of life and economic climate continues to lure people to our state. The latest U.S. Census Bureau figures estimate Washington’s population grew by nearly 88,000 from July 2013 to July 2014. That’s like adding another Kent, Federal Way or Yakima. The solution to traffic congestion is multi-pronged and requires all modes of transportation to be available, from walking to flying. Ramp meters are one component to help get us closer to a solution.

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