Overpasses, tunnels, express buses and better traffic signal synchronization could someday be used to break traffic bottlenecks at key Sahara Avenue intersections as part of concepts considered by regional planners.

Sahara is the first of three major east-west streets that the Regional Transportation Commission hopes to keep as viable major crosstown streets, alleviating pressure on the Las Vegas Valley's two major freeways, Interstate 15 and U.S. Highway 95.

The other streets under review are Flamingo Road and Tropicana Avenue.

"We're trying to squeeze out all available capacity on these streets, and maintain the quality of life in our community," Jerry Duke, a commission planning manager, said before a Tuesday public hearing at Winchester Community Center unveiling the Sahara plan and seeking public input.

That plan is aimed at allowing more cars and faster-moving traffic on Sahara, which today carries as many as 70,000 cars and trucks each day. That traffic volume is expected to more than double in the coming years.

Planners have yet to pick final alternatives or find funding for the work, which could cost as much as $400 million to construct and has no solid time lines to start or finish work. "These studies aren't magic," Duke said. "They don't just create the money."

In the central and eastern valley, plans call for replacing intersections with highwaylike interchanges that would allow so-called "through traffic" to continue along Sahara without stopping, while still allowing local traffic to enter or exit Sahara.

That would be done by what engineers call "grade separation," or putting different kinds of traffic on different levels above or below each other.

At Las Vegas Boulevard South, engineers are considering building tunnels under that intersection to allow through traffic to bypass stoplights where the two streets meet, while local traffic would stay on surface lanes that would maintain turning access onto or off of the Strip. That plan is pegged at $132 million.

For about half that cost, engineers could instead build a parallel Sahara "couplet" road that would cross Las Vegas Boulevard at a different intersection. Each section then would carry opposite directions of one-way Sahara traffic, in theory improving traffic flow. But that plan would require demolishing some property just north of Sahara, roughly between Paradise and Industrial roads.

On East Sahara, engineers propose building $134 million worth of overpasses and underpasses to carry Sahara through traffic past intersections at Maryland Parkway, Eastern Avenue and Boulder Highway nonstop.

Similar overpasses were considered for West Sahara, but ultimately dropped because of the need for as many as a dozen closely-spaced interchanges that would be too costly and unwieldy to build. Traffic modeling indicated building fewer overpasses there wouldn't help traffic.

"They're so closely spaced that if you put one up and not the remainder, you're just pushing the bottleneck along" to other intersections, Duke said.

Instead, engineers will work on building right turn-only lanes, restricting left turns and otherwise improving traffic signal coordination on West Sahara, at a cost of around $7 million, in hopes of better utilizing existing traffic lanes there.

Also, part of the plan is to introduce express bus service along the entire length of Sahara that would be similar to the Metropolitan Area Express "MAX" service now plying Las Vegas Boulevard North.

Such buses use limited, train station-like stops and bus-only lanes to move more quickly than traditional bus routes. Depending on how a route is structured, the cost could be up to $111 million to start.

"The study is all about mobility, and not just traffic movement," Duke said.

With the exception of the "couplet" option, it's unlikely that much additional property would need to be bought for the work. Virtually all of Sahara already has rights of way of 140 feet or more, while most road work scenarios require less land than that.

Duke said he hopes to get comment from the public, Regional Transportation Commission board, Clark County Commission, Las Vegas City Council and other interested parties before coming up with final recommendations later this year. Then, if the plan is approved by those various government entities, the hunt for funding would begin.

Duke said possible funding sources include the federal and state government or Question 10 sales taxes dedicated to transportation projects, though ultimately it will be up to elected officials both in Nevada and Washington, D.C., to decide if or when to fund the work, and how much to contribute.

If the project is approved and funded, the West Sahara work would likely go first, followed by the Strip work, then the launch of express bus service, and finally the East Sahara work. A proposed time line was not offered this week.