The environmental assessment for proposed improvements to U.S. Highway 24 west will be submitted to the federal government for its approval in 2010. The plan, which sketches out the look of the proposed expressway, its impacts and how experts plan to mitigate those, has lot of details, some still to be worked out. But its broad outlines are straightforward:

• Eight lanes on the short stretch of Highway 24 from Interstate 25 to Eighth Street, then six lanes to 31st Street.

• Interchanges at Cimarron Street and I-25 and at Eighth and 21st streets, all designed like the one at Garden of the Gods and I-25.

• Four-way intersections with stoplights at 26th and 31st streets.

• A bridge to carry highway traffic over Ridge Road, west of 31st Street, with no offramps.

• A speed limit of 50 miles per hour.

Included in the plan but not funded by state highway dollars are a few ideas either proposed or supported by many west-side residents: an overpass at 15th Street; a cut-off from Broadway Street off 21st Street to Eighth Street, along the base of Gold Hill Mesa; and potential ramps for the Ridge Road bridge. A greenway along Fountain Creek, which follows the highway, is envisioned but wouldn't be funded by the Colorado Department of Transportation.

Extensive work around 31st Street, including moving the Safeway there, has been dropped from the plan.

The expected cost of the project: $230 million. Another $40 million would be spent to acquire 61 commercial properties and six residential properties that need to be removed.

The tentative construction schedule: Between 2016 and 2020, the state would build the Cimarron and I-25 interchange, the Eighth Street interchange and the eight lanes of road between them.

By 2030, CDOT will have built the interchange at 21st Street, the six lanes along the length of the highway, the bridge over Ridge Road and the upgraded intersections at 26th and 31st streets.

Craig Casper of the Pikes Peak Area Council of Governments said the Cimarron and I-25 interchange - already approved in the COSMIX environmental assessment - could theoretically be started in two or three years. But he said it makes sense to delay that work until both it and the Eighth Street interchange can be built at the same time. Doing them together could save money and minimize inconvenience to drivers.