WSDOT is entering a new era in fighting congestion. New technologies that more evenly distribute traffic and warn drivers of problems down the road are redefining how traffic engineers manage both transportation systems. At the heart of all this new technology is the ability to adapt to constantly fluctuating highway conditions and respond in the most efficient manner. Some of the new tools include:
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HOT Lanes:High occupancy toll (HOT) lanes make highways more efficient by allowing just enough additional traffic into underused carpool lanes. An electronic toll that fluctuates with the level of congestion lets solo drivers use carpool lanes reserved for vehicles with two or more occupants. The dynamic pricing keeps the HOT lane free flowing while reducing congestion in the general purpose lanes. The state’s first HOT lanes will begin a four-year test period on SR 167 between Renton and Auburn this spring. There are six HOT lane facilities successfully operating in other states and several others are in development.
Express Toll Lanes: In the not-so-far-off future, WSDOT might use other forms of congestion pricing like HOT lanes on highly congested freeways, such as I-405. Express Toll Lanes would offer an escape from congestion with an electronic toll that fluctuates with the level of demand. The result would offer commuters more choices and help reduce congestion in all the lanes.
Tolling: Tolling and variable tolling can be used to manage the amount of traffic in a lane or on a roadway. WSDOT’s Good To Go! electronic tolling system allows users to pay a toll without stopping at a toll both. Tolling also could help pay for vital capacity improvements, such as those planned for the SR 520 corridor.
Active Traffic Management:Active Traffic Management (ATM) technology dynamically controls traffic based on prevailing conditions. Using integrated systems and a coordinated response, both recurrent and non-recurrent congestion can be managed to improve roadway safety and traffic flows.
WSDOT is studying ways to improve traffic flow and testing new techniques to manage traffic on the region’s busiest routes. New ATM tools that soon could help reduce congestion here include:
Overhead gantries - to display variable speed limit and real-time traffic information over each lane.
Speed harmonization - to dynamically and automatically reduce speed limits approaching areas of congestion, collisions, or special events.
Queue warning - warn motorists of downstream queues (or backups) and direct through-traffic to alternate lanes.
Junction control - to use variable traffic signs, dynamic pavement markings, and lane use control to direct traffic to specific lanes (mainline or ramp) based on varying traffic demand.
Hard shoulder running - to use the shoulder as a travel lane during congested periods or to allow traffic to move around an incident.
Dynamic rerouting - to change destination signs to account for current traffic conditions.
Travel time signs -to display estimated travel time and other condition reports as well as communicate travel and traffic conditions. |
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Tour HOT Lanes
Take a virtual drive with Rachel along the SR 167 HOT Lanes, which are scheduled to open this spring.
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Simulated photo of I-405's proposed two-lane express toll system. Enlarge photo.
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Traffic in 2032
Over the next 25 years, projected increases in population and jobs for the central Puget Sound region will worsen today’s gap between transportation demand and capacity. If the trend continues, commuters could spend 300 percent more time sitting in traffic. A recent study projecting central Puget Sound traffic congestion under current traffic models in 25 years predicts:
• 1.1 million hours of traffic delay per day
• 40 percent more vehicles
• Deteriorated traffic flow in all corridors with an average of nine hours of congested traffic conditions daily along heavily traveled corridors.
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Overhead gantries on England's M42 near Birmingham display variable speed limits over each lane and can close lanes in the event of an emergency.
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| This conceptual rendering illustrates how ATM tools, such as overhead gantries with variable speed limits and driver message signs, could help ease congestion on I-405. |
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