Smart 25 Pilot Project: Coordinated Ramp Metering System on I-25 from Ridgegate Parkway to University Boulevard

Project Facts

  • Project: Testing new ramp metering system aimed to reduce congestion
  • Timeline: Fall 2021 to Summer 2022
  • Location: Northbound I-25 between Ridgegate Parkway and University Boulevard 

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About the Pilot Project

This is a pilot project to test a new ramp metering system with the goal of reducing congestion and improving travel times on northbound I-25 between Ridgegate Parkway and University Boulevard.  Sensors measure traffic volume on I-25 and along the on-ramps to the highway.  Since the fall of 2021, this information has been gathered for all 18 arterial ramps along the corridor and used to control the timing of the lights that allow vehicles to enter the highway with the intent to reduce stop-and-go traffic.  Beginning the week of February 28, the system activated new ramp meter signals on the southbound I-225, eastbound C-470 and westbound E-470 on-ramps to northbound I-25. 

The pilot project will sunset Friday, July 29, 2022.  CDOT will pause the program to evaluate the data.  During the evaluation phase, the ramp metering system will operate as it did before the pilot, and the Smart 25 ramp meters will be turned off at the freeway to freeway ramps - the I-225, C-470 and E-470 on-ramps to northbound  I-25. Following the analysis, CDOT will determine if permanent deployment is possible.

This system has worked successfully in Melbourne, Australia.  Traffic flow increased by 25% and speeds improved 35% to 60% during peak travel times, the equivalent of adding a lane at the fraction of the cost. The Smart 25 Pilot Project is the first of its kind in Colorado and North America. 

I-25 between Ridgegate and University is similar to the corridor in Australia where such a ramp metering system has been very successful.   

Watch the video on how the pilot project works


2021/2022 Testing Schedule and Traffic Impacts 

Summer 2021 – Data collection phase.  No traffic impacts.

Fall 2021 to summer 2022 – The new ramp metering system was activated incrementally to provide an adjustment period for drivers and allow for system tweaks.  The signals turn on as needed on real-time data.

Traffic impacts:

  • The new ramp metering system was activated on all 18 arterial ramps along northbound I-25 from Ridgegate Parkway to University Boulevard fall of 2021.  
  • Drivers may notice various wait times behind the ramp meters.  The timing is based on real-time traffic conditions to better control the flow of traffic onto the highway with the goal of improving traffic flow during congested periods.
  • The right shoulder lanes can be used on some of the ramps when the meters are on.  Those are the westbound Lincoln Avenue, Dry Creek Road, westbound Arapahoe Road and Orchard Road on-ramps to northbound I-25. The use of the part-time shoulder lanes allow more drivers to enter the interstate more quickly, while preventing impacts to nearby local roads. The shoulder lanes can be used ONLY when ramp metering is activated.  
  • Motorists are urged to be watchful of the ramp metering activation signs. 

Week of February 28, 2022 - Freeway to freeway ramp metering activation 

  • Four ramp metering signals were activated at the end of each of the I-225 and C-470 on-ramps to northbound I-25.  Two new ramp meters were also activated on the westbound E-470 on-ramp to northbound I-25. 
  • When the ramp meter lights are activated, flashing signs warn motorists to slow down and be prepared to stop.
  • Motorists can use the left and right shoulder lanes on the I-225 and C-470 on-ramps when the ramp metering system is activated.
  • Traffic has been closely monitored and ramp meters adjusted as needed.

Summer 2022 - The testing period continues through Friday, July 29.  Following the pilot, the data collected from the system will be evaluated to determine if permanent deployment is possible.  After July 29, the ramp meters will operate as the did before the pilot project and the Smart 25 ramp meters will be turned off at the freeway to freeway ramps - the I-225, C-470 and E-470 on-ramps to northbound I-25. 

Late fall 2022 - A final report on the project is expected later this fall, and depending on the findings, permanent deployment is possible.  

Dry Creek Road Ramp Meters Sign.JPEG

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Resources

Smart 25 Project Fact Sheet, January 3, 2022

Smart 25 Project Update, March 24, 2021