Downtown drivers should steer clear of State Street from now until fall.

The horn honking and traffic snarls started Thursday with construction beginning on an underground pedestrian tunnel connecting the ZCMI Center and Social Hall Avenue.And the hassles will increase as the city soon starts tearing up sidewalks between South Temple and 200 South as part of its State Street beautification project.

Further complicating matters for motorists will be trucks pulling in and out of the Utah One Center/

Block 57 Plaza and Broadway Centre construction projects.

But the interference doesn't stop at 300 South. This summer state crews will install new traffic signals and resurface intersections from 400 South to 900 South.

"There will be lots of things going on," said Jerry Blair, deputy transportation engineer for Salt Lake City.

The city will be responsible for providing pedestrian walkways along the street and access to stores during construction, Blair said. And the Utah Department of Transportation will oversee traffic flow because State Street is a state highway.

While the underground walkway is being built, two narrow lanes of traffic will be open in each direction. To accomplish this, UDOT will take out the raised median and eliminate parking and access to the far right hand lanes between South Temple and 100 South during the underground walkway's construction.

But cars will still be packed in tightly, said Tom Smith, pre-construction engineer for UDOT's district two office.

"It will slow traffic down, and large trucks will make it difficult," he said.

Far right-hand lanes will also be blocked off to driving and parking between 100 South and 200 South because of the city's beautification project involving the installation of new sidewalks and tree planters.

Sidewalk replacement will extend down the north side of 200 South to Regent Street. That section of 200 South is now a one-way street for westbound traffic because of Block 57 construction. But by the time beautification crews reach 200 South, the section will have been restored to two-way traffic, officials said.

Traffic interference along State Street should start to subside by October when the underground walkway and sidewalk replacement are scheduled for completion.