Colorado and the Colorado Department of Transportation specifically, was an early adopter of roundabouts to improve intersection safety. Examples include several I-70 interchanges in the mountain corridor area, I-25 north of Denver, etc. During major projects, CDOT often installs roundabouts in place of regular intersections to improve safety.
What is a DDI? – A Diverging Diamond Interchange (DDI) crosses traffic to the opposite side of the road across an interchange so vehicles have unimpeded movements onto the freeway ramps. Left-turn movements, which are a typical challenge with standard four-way interchanges, are eliminated with a DDI.
The new Flashing Yellow Arrow (FYA) traffic signal light is replacing the traditional circular, steady green signal for “permitted” left turns at certain intersections in many cities. The flashing yellow arrow indicates when left turns are permitted ONLY AFTER YIELDING TO ONCOMING OR CONFLICTING TRAFFIC AND PEDESTRIANS. Remember: A flashing yellow arrow = Turn with caution.
CDOT actively upgrades intersections with what are called “mast arm” traffic signal pole configurations (often mounted at all four corners of the intersection). This replaces the old diagonal “span wire” mounted traffic signals. The new mast arm mounting allows individual traffic signal “heads” to be positioned over each driving lane to improve signal visibility and understanding.
For general pedestrian safety, countdown pedestrian signals and longer walk phase times are being phased into many intersections during upgrades.
The use of advance street name signs and advance warning signs have also been a staple of CDOT highway design. These give drivers a “look ahead” which allows them to prepare for a change in the driving regime or help with navigation.
Ongoing testing and reviewing of improved pavement marking methods and materials are occurring that eventually will assist the driving public to better negotiate roads both day and night and in inclement weather.
“SHARROWS” or Shared Lane Markings are relatively new road markings in Colorado. They are seen more commonly on low-speed roadways in cities and other urban areas that encourage various forms of travel. They help show bicyclists where to ride in a narrow lane that they share with cars. These markings also help to alert motor vehicle drivers of the potential presence of bicycles and to pass with caution and sufficient clearance.
Yield line pavement markings or “Sharks Teeth” are triangular markings used to inform the driver of where they are required to yield or stop for other traffic and/or pedestrians. These lines are found at intersections, roundabouts and sometimes seen between intersections at mid-block pedestrian crossings.
Speed hump (or speed table) markings are triangular pavement markings that show drivers where a raised section of pavement or speed hump is located so they can slow down to prevent a rough ride or car damage. Speed humps can be used as traffic calming or slowing features or can identify marked or unmarked crosswalks.
A green bike lane is green-colored pavement that enhances the visibility of abicycle lane in places where there is a potential for conflict with motor vehicles.
Driving Through Multi-Lane Roundabouts
Choose your lane as you approach the roundabout just like a regular intersection:
TO TURN RIGHT OR CONTINUE STRAIGHT AHEAD ON THE ROAD
Get in the right lane and plan to use the right lane of the roundabout.
TO TURN LEFT OR CONTINUE STRAIGHT AHEAD
Get in the left lane and use the left lane of the roundabout.
TO MAKE A U-TURN
Plan to use the left lane in the roundabout.
At the yield line and yield sign you see just before entering the roundabout, you must YIELD TO TRAFFIC IN BOTH LANES of the roundabout because you need to choose which lane to enter.
Always watch for pedestrians and bikes when you approach the roundabout, while inside of and as you exit the roundabout, because crosswalks often are located just outside of the roundabout.
For safety, don’t change lanes, stop or pass another vehicle while in the roundabout.
Don’t drive next to large trucks and buses in roundabouts because, due to their length, they often need both lanes to make their turn.
Remember, you can take it slow.
Driving Through Divergent Diamonds
Example: I25 and Fillmore DDI Colorado Springs, CO
Continuous Flow Intersection (CFI)
Example: Woodman Road Corridor Improvement Project Phase 2