Minnesota Department of Transportation

511 Travel Info

Ramp meters

A ramp meter.

The goals of ramp meters

With ramp meters, MnDOT aims 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

  • MnDOT installed the first meters on I-35E at the entrance ramps from Maryland Ave 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 a.m. - 9:00 a.m.), some only during the afternoon peak (2:00 p.m. - 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.

Your frequently asked questions

Why am I waiting 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 is the meter running 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 4 minutes. If there are too many vehicles on the ramp, this causes back ups onto local streets. The RTMC then changes the timing on the meter so that more vehicles can flow onto the mainline.

Why are meters continually flashing yellow when the highway is stop and go?

MnDOT 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.

Can I use my MnPASS transponder to use the ramp bypass lane?

No, drivers can only use transponders on the I-394 and I-35W MnPASS Express Lanes.