Project overview
WSDOT contractor crews, Northeast Electric Inc., installed new ramp meters at several on-ramps along northbound Interstate 5 and southbound Interstate 205 in Clark County.
Ramp meters, a type of traffic signal, are employed to regulate the rate at which vehicles enter the freeway, serving as an effective strategy to enhance freeway operations. These meters aim to minimize collisions and decrease travel times. By controlling the flow of vehicles entering the freeway, ramp meters effectively alleviate congestion by limiting the number of cars occupying the same space simultaneously. This approach also mitigates merging challenges that arise when numerous vehicles attempt to merge into a nearly full lane.
Project locations for the new ramp meters installed on the northbound I-5 Fourth Plain Boulevard on-ramp and several on-ramps along southbound I-205.
Ramp meters are traffic lights that control the frequency in which vehicles enter the flow of traffic on to the interstate during peak travel times. They are a proven cost-effective tool to reduce congestion while improving traffic flow and safety by providing spaced intervals between vehicles, rather than having multiple vehicles enter the freeway at once, clogging up the system. More efficient merging allows mainline traffic to continue travelling smoothly and keeps traffic flowing at highway speeds.
How to use ramp meters
Drive your vehicle up to the white line, or stop bar/fog line, to trigger the ramp meter. If the light is red, stop at the white line. When the light turns green, continue to merge onto the freeway.
Ramp meters are part of a large computer-operated system that is managed in WSDOT's Traffic Management Center (TMC). Electronic monitoring systems provide the TMCs with information about traffic flow, such as the volume and speed of vehicles on highways and ramps. Data is fed to the ramp meters. The meters automatically alter cycles to maximize traffic flow on both the ramps and the freeways.
Ramp meters cause less disruptions to highway traffic
Without ramp meters, multiple cars merge simultaneously. Drivers on the highway slow down to allow the cars to enter and these slower speeds quickly cause backups. If cars enter the highway in controlled intervals, they are less likely to cause a disruption to highway traffic.
A short wait on the ramp allows drivers to increase their average highway speed and shorten overall highway travel times. Ramp meters also decrease the potential for collisions, by up to 30 percent, that often occur when multiple vehicles merge onto the highway at the same time.
We use ramp meters to reduce collisions and decrease travel times
Most ramp meters allow only one vehicle through each green light, creating a 4 to 15 second delay between cars entering the highway. This delay helps reduce disruptions to highway traffic and reduces collisions that occur when vehicles merge onto the highway.
Will the ramp meters cause backups on local streets?
There is always an adjustment period after new ramp meters are activated. This is the timeframe when the public becomes accustomed to using them. WSDOT will monitor traffic flows and make any adjustments to the meters if necessary.