This simulated view looking west over C-470 toward Santa Fe Drive shows RTD's Southwest Corridor Extension curving into Highlands Ranch from Mineral Station. The station in the picture is a future intermediate stop before Lucent Boulevard.

RTD’s FasTracks plan to build an extension to the Littleton light rail line faces few environmental hurdles along the 2.5-mile route from Mineral Avenue to Lucent Boulevard in Highlands Ranch.

The biggest hurdle it faces is being at the end of the line for funding from the overall FasTracks budget, which has a $2.2 billion shortfall trying to pay for $6.9 billion worth of work by 2017.

The Southwest Corridor Extension is currently priced at $165.6 million. Only the Central Corridor light rail extension from Five Points to a transfer station for the proposed line to DIA is estimated at less cost.

The Southwest extension’s most expensive element is a large, curving flyover bridge to take the double-tracked extension over the top of the complex C-470/Santa Fe Drive interchange where two freight railroad bridges and a proposed highway ramp by the Colorado Department of Transportation also compete for space.

The environmental evaluation found minimal impacts other than during the construction period itself, for which it lays out mitigation measures. You can read the executive summary of the document here. RTD identified some visual impacts as well as impacts on the Highline Canal, trails and a historic Denver & Rio Grande Western Railroad trestle that must be removed. RTD says it will protect the canal and trail by routing them through a large concrete box culvert for the light rail to pass overhead.

Rendering of the light rail flyover bridge at C-470 and Santa Fe Drive.

Finding the financial resources to go from the drawing board to the dirt will be the biggest problem for this project.

On the original FasTracks schedule circulated when voters approved a four-tenths cent sales tax to pay for it in 2004, the Southwest Corridor Extension was to be one of the last to come on line in late 2016, along with an extension to the Southeast Corridor light rail – the T-REX line that opened in 2006. The reasoning for that was so that other parts of the metro area currently without any rail transit service would have their lines opened first before communities that already have rail get more.

But now, with RTD short on financial resources, the Southwest extension is in the same boat as the at-risk lines along Interstate 225 and in the north metro area – and that boat is adrift in a shallow sea of finances.

RTD is considering asking voters for a second sales tax increase to fill in the gap and finish all the lines by 2017. It is working with groups such as the Metro Mayors Caucus on a consensus over how and when to proceed.

RTD now figures that without a second tax increase for which it may seek voter approval as early as next year, it can only afford to fully finish the West Corridor light rail to Golden, the East Corridor heavy-rail project to Denver International Airport and the Gold Line heavy rail to Arvada and Wheat Ridge. Enough funds would be left over to build only short beginning stubs of three other new rail lines.

And if it also fails to secure federal grants for the Gold Line or East Corridor, the Gold Line could be put on hold.

The FasTracks Southwest Corridor team presented results of a year-long environmental evaluation and preliminary engineering at a public meeting Wednesday evening in Littleton City Hall. The results are rather straightforward. There is only one station on the extension in the current budget, and that’s the new end-of-line at Lucent Boulevard on the south side of C-470. But RTD is planning for a later addition of an intermediate station along C-470 at Santa Fe.

Click here to go to an interactive map of the Southwest — and Southeast — extension projects that allows you to make geo-tagged comments on the studies.

Littleton Mineral Station is the current southern end-of-line for the Southwest Corridor.

The Lucent Station, with a parking garage and 1,000 total parking spaces, would draw riders from adjacent Highlands Ranch who currently drive to Mineral.

RTD isn’t required to do a full-blown environmental impact study on the extension since no federal funds are involved. And because there is no obvious lead federal agency to act as overseer of a smaller scale environmental assessment, RTD designed its own in-house “environmental evaluation” process to mirror the bigger studies in many of the other FasTracks corridors. RTD’s goal was to ensure each corridor project in FasTracks, whether required or not, was subjected to similar study and public scrutiny. In this case, it is up to the RTD board to act on the results.

Map shows the study area of the FasTracks Southwest Corridor extension.