The goals of ramp meters
Ramp meters are traffic signals on highway entrance ramps designed and proven to:
- Reduce crashes
- Reduce congestion
- Provide more reliable travel times
With ramp meters, we aim to ensure that:
- Wait times are no longer than four minutes per vehicle on local ramps and two minutes per vehicle on freeway-to-freeway ramps
- Vehicles waiting at meters won't back up onto adjacent roadways
- Meter operation responds to congestion and operates only when needed
Background facts
Metro meters
- We installed the first meters on I-35E at the entrance ramps from Maryland Avenue and Wheelock Parkway in St. Paul in 1969.
- The Twin Cities Metro Area has 433 ramp meters. Some operate only in the morning peak (5:30-9 a.m.), some only during the afternoon peak (2-6:30 p.m.), and others during both peaks.
Activation factors
- Factors that determine the timing rates of ramp meters include congestion conditions on the freeway and real-time traffic levels on the metered ramp.
- Ramp meters react to freeway congestion conditions up to three miles from the ramp. Queue detectors help determine queue lengths and prevent long waits. Meter timing adjusts every 30 seconds.
Answers to common questions
Why you wait on the ramp when the mainline is free flowing
Ramp meters react to actual travel conditions by delaying the onset of congestion. By allowing vehicles to enter the freeway one at a time, this precludes large numbers of vehicles from joining traffic all at once. This would create slowdowns around the entrance ramp and increase travel times.
Why the meter runs fast when the highway is stop and go
The ramp metering policy provides a balance between maximizing the efficiency of the freeway system with traffic flow on the local streets while keeping ramp waits to less than four minutes. If there are too many vehicles on the ramp, this causes back ups onto local streets. The Regional Transportation Management Center (RTMC) then changes the timing on the meter so that more vehicles can flow onto the mainline.
Why meters continually flash yellow when the highway is stop and go
We decided not to meter at certain locations. These ramps either carry too little traffic to justify activating the meter or else they have too much traffic to effectively meter without exceeding the maximum queue waits.
You cannot use your E-ZPass transponder to use the ramp bypass lane
Drivers can only use transponders on the I-394 and I-35W E-ZPass express lanes.