What you're referring to is the Desert Inn Super Arterial.
This $92 million, two-mile, six-lane, east-west, no-light thoroughfare took three years to build and opened in April 1996. It runs from Paradise Road (at the Las Vegas Convention Center on the east side) to Valley View Boulevard (on the west); en route, it passes the Wynn Golf Course, then tunnels under the Strip and goes over Industrial Road, Highland Drive, and I-15 on a massive overpass. The cross-town drive, which used to take up to 15 minutes on Desert Inn Road, now takes less than three.
The Super Arterial serves about 80,000 vehicles daily; it's so successful that traffic engineers are considering super arterials for avenues like Tropicana and Sahara.
The road is a convenient way to cross the Strip without having to stop. When traffic is backed up on Flamingo Avenue (to the south of it) and Spring Mountain/Sands Avenue (to the north), a quick hop over to Desert Inn can save a lot of time.
Also, it's a quick way to reach the Convention Center from the west side. If you're staying, for example, at the Rio, Gold Coast, or Palms (or even the Orleans), all you have to do is head up Valley View (the north-south road that runs between the Rio and Gold Coast), negotiate two traffic lights (at Twain and Spring Mountain), hang a right on the Super Arterial, and you're at the Convention Center in two to three minutes flat. Painless.
