It's a list that frustrated motorists may be all too familiar with: the most congested traffic hot spots in the metro area.

But now, for the first time, regional traffic planners hope to zero in on what, specifically, makes the area's busiest intersections, highway ramps and freeway segments as troubled as they are.

As you plod along today through First Avenue and University Boulevard, Interstate 25 from Thornton to Denver and C-470 across Highlands Ranch, or wait on the off-ramp at the Wadsworth Boulevard exit from Hampden Avenue, you can probably guess what locations made the first cut.

The purpose of the detailed map is to identify the key locations where traffic congestion is at its worst. A preliminary draft to be discussed today at the Denver Regional Council of Governments is subject to change over the next year of study.

But it represents the likely suspects for the most troubled spots.

So far, the planners' map includes 31 of the most congested intersections, 27 of the most backed-up exit ramps and 21 of the worst freeway choke points.

But the map is "still undergoing review," said DRCOG transportation planner Steve Cook. Local governments that are members of DRCOG will go over the list and do their own research. The group plans to refine the data over the next year.

DRCOG regularly quantifies the traffic loads on congested corridors. But this study will go further than simply identifying congested stretches.

It will drill down into the data to come up with the key intersections, access ramps and bottleneck areas that contribute to the overall congestion on a freeway or major arterial road.

To verify what the preliminary data show, the DRCOG staff is asking communities to look over the list and see if the locations conform to the on-the-street experiences in their cities and towns.

DRCOG won't use the list to rank future road construction projects, although the study will provide additional information for highway decision-makers who plan where to spend money for improvements.

Decisions on funding road projects will be based on additional analysis of the impacts each individual proposal would have.

The metro area has more than 3,500 intersections with traffic signals designed to keep cross traffic moving, but on congested arterials, it can take two or three signal cycles for drivers to get through.

In addition, in spots where signals are used at the ends of freeway on-ramps, traffic volume can sometimes build to the point that there's not enough green time to avoid backing up traffic on the connecting street.

In the worst cases, traffic waiting on the ramps can stack up onto the freeway lanes, creating a significant safety hazard.

Finally, there are locations on the metro freeway network where it's predictable to have bottlenecks. It might be due to one lane dropping off, forcing a merge, sharp curves or hills, or busy interchanges with lots of traffic weaving and merging to get on or off.

The meeting to share the findings with local agencies is at 1:30 p.m. today in DRCOG's first floor boardroom, 4500 Cherry Creek Drive South in Denver. It's open to the public.

Slow-going

3,500 intersections with traffic signals aim to keep cross traffic moving in the metro area. But on some congested arterials, it sometimes can take two or three signal cycles for drivers to get through.