Like other metro areas in the US, CDOT uses ramp meters
to manage traffic on the freeway system. For those who don't know, a ramp meter is a signal part way down a
freeway onramp that is red part of the time and turns green at
intervals, usually allowing one vehicle per lane at a time through, to manage
the amount of traffic entering the freeway.
Ramp meters can be looked at as doing two things: 1) They prevent traffic from entering the mainline in large clumps all at once, improving the performance of the merge area, and 2) can also be used to proactively restrict the number of vehicles entering the mainline to keep it from reaching capacity. The overall theme is that the people on the ramp are being sacrificed (by making them wait longer) in order to improve the performance of the mainline.
One beef I have with how CDOT operates the meters is that the meter for each lane turns green at the same time, rather than being staggered. The result is almost a game of chicken as each driver screams out of the starting block to try to be first to get to the point where the ramp tapers back to one lane.
In Colorado, ramp meters are used on most of the freeways in metro
Denver. Nearly every interchange along I-25 and I-225 has them, plus
numerous interchanges along I-70, I-270, US 6, US 36 and C-470. Outside
metro Denver there are meters at several I-70 interchanges in the
foothills west of Denver.
A typical CDOT ramp meter, at the northbound onramp to I-25 at Evans Avenue as it appeared before T-REX construction.
Created 13 May 2001
Last updated 18 March 2011