PITTSBURGH (KDKA) – The so-called “CAP Project” uptown in Pittsburgh is unusual in many ways.

The project is the construction of a park that will connect the old Civic Arena site to the Golden Triangle.

It’s being done by the Sports and Exhibition Authority and City of Pittsburgh, but it requires the closing of a PennDOT ramp and restrictions on the driving lanes of I-579.

So the SEA can get to work, the ramp to Seventh Avenue and Grant Street closes tonight for two years.

“You can’t build a bridge without being underneath it,” PennDOT’s Assistant Executive for Construction Jason Zang says.

The ramp will be the staging area for the contractor’s equipment and an area to launch work.

And what does it mean to drivers? If you come into Pittsburgh from the east and use the Boulevard of the Allies when you exit to the Veterans Bridge and Crosstown Expressway, the left lane will close because that’s the ramp to Seventh which is closing.

WATCH: KDKA’s John Shumway talks detours —

It means if your destination is downtown, you’ll have to immediately merge right into the flow of traffic from the Liberty Bridge and exit at Centre Avenue/PPG Arena exit.

Caution: there is not a lot of asphalt to make that merge over to the official detour exit ramp.

Right now, some drivers go that way, but the couple thousand that use the Seventh Avenue ramp will be joining that flow come Monday.

Zang isn’t concerned.

“There’s the weave happening now,” he said. “The Boulevard of the Allies traffic and the Liberty Bridge traffic they’re weaving now to get to those various off-ramps.”

The weave from Liberty Bridge traffic to Seventh Avenue will end with the closing, but now everyone will be using the PPG ramp detour route.

“I anticipated the biggest problems to be at that PPG off-ramp to Center Avenue. We do have officers planned to be at every one of those intersections.”

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If you are coming into town from the Liberty Bridge, you have a couple of options.

You can exit at the Boulevard of the Allies ramp and turn left into the city. Zang says as of now, there will not be anyone assisting at that intersection. “We don’t have it planned right now but we’ll keep a close eye on it. If we see it backing up there we’ll make adjustments,” he said.

The other alternative coming off the Liberty Bridge is to take the Sixth Ave/Forbes Avenue exit into town. Or, you can use the I-579 ramp to the posted detour at PPG. Zang expects, “Monday and Tuesday will be the worst, just until people figure out what’s going on.”

While this will be a daily commuting challenge there are a couple of other things to keep in mind:

  • If you miss the posted detour exit you will be heading for Bloomfield, or the North Shore.
  • This will have an impact on crowds coming to Penguins Games and concerts at PPG Paints Arena.
  • Coming from the south or east you may need to choose another path to get to the Strip District for your Saturday mornings.

Again, the ramp will be closed for about two years.