The state Department of Transportation's Transportation Improvement Plan is a constantly evolving four-year plan to improve roads and bridges in southwestern Pennsylvania.

Here is a list of state projects planned in several areas in Butler County.

All projects beyond this year are subject to available funding.

Butler Minor details remain to be finished on the new Wayne Street Bridge, which was completed and opened in October, as well as demolition of the old viaduct.

Butler TownshipRoute 422 was repaired in 2009 between Whippoorwill Road and Duffy Road, including updated guide rails and signs, at a cost of about $1.4 million. No other state work is scheduled in the township through 2014.

Northeast regionThe county's northeast region covers Allegheny, Center, Concord, Donegal, Fairview, Oakland, Parker, Venango and Washington townships.• Allegheny Township — Construction contracts were awarded in January for replacement of the Sedwick's Mills Bridge carrying Route 38 over the Little Scrubgrass Creek. The project should be done by October for $2.5 million to $5 million.Replacement of the Sandy Point Bridge along Route 38 is scheduled for 2014.• Center Township — The Stoney Run Bridge along Route 308 is scheduled to receive a $1.6 million rehabilitation with work to be done by September.• Concord Township — Replacement of the Harbor Acres Bridge, which carries Route 138 over the Slippery Rock Creek, is slated for 2012 at a cost of $1 million to $5 million each.Replacement of the bridge south of Hooker on Route 38 is slated for 2013, and replacement of the Greece City Bridge along Route 38 is scheduled for 2014• Oakland Township — Replacement of the bridge southwest of Boydstown along Route 38 in 2013• Petrolia — Replacement of the Petrolia Bridge along Route 268 is expected to cost $1 million to $5 million. The project is in its final design phase and work is scheduled to start in 2011.PennDOT officials have said work on the two bridges might begin this year if funding becomes available.• Washington Township — PennDOT staff will replace the Hilliards Bridge along Branchton Road in 2011.

Southeast regionThe county's southeast region covers Buffalo, Clearfield, Clinton, Jefferson, Middlesex, Penn, Summit and Winfield townships.• Buffalo Township — PennDOT repaired the Sandy Lick Bridge in 2009 using stimulus money, but no other projects are planned in the township through 2014.• Clearfield Township — PennDOT completed a $5 million resurfacing of 6.8 miles of Route 422 from Game Reserve Road to Worthington, Armstrong County, in October.No other work is planned soon in the township.• Freeport — A four-year, $88 million reconstruction of the Freeport Bridge, which carries Route 356 over the Allegheny River at the corner of Allegheny, Armstrong, Butler and Westmoreland counties, will begin in June.The project also includes the replacement of the nearby Laneville Bridge over Buffalo Creek.The design will add two new traffic signals, one at the intersection of Second Street and Freeport Road and another at the new T-intersection at Freeport Road at the north end of the bridge.• Jefferson Township — The Thorn Creek Bridge, on Water Street between Hannahstown and Frasier roads, is scheduled for replacement in 2012 at a cost of between $1 million and $5 million.• Penn Township — The McBride Bridge, which carries Route 8 over the Thorn Creek near Renfrew Road, is scheduled for a $1 million to $5 million rehabilitation.The project is in its final design phase and work is scheduled to start in 2011.• Winfield Township — PennDOT staff will replace the Leasureville Bridge in 2011.Southwest regionThe county's southwest region covers Adams, Connoquenessing, Cranberry, Forward, Jackson, Lancaster and Muddy Creek townships.• Adams Township — A $10 million to $15 million replacement of the Mars Railroad Bridge along Route 228 is scheduled for 2012.• Connoquenessing Township — Replacement of the Little Connoquenessing Creek Bridge along Route 38 is scheduled in 2013.PennDOT used stimulus money to repair the Shannon Road Bridge in 2009.• Forward Township — PennDOT used federal stimulus funds to repair the Ribold Bridge and to replace the Wahlville Bridge carrying Route 528 over the Connoquenessing Creek in 2009, but no other work is planned in the township through 2014.• Jackson Township — Replacement of the Harmony Junction Bridge should be done by June at a cost of $5 million.• Jackson and Lancaster townships — PennDOT will start work on the Interstate 79 connecting ramps in each township this year. The project will upgrade the existing ramps while adding two others to improve traffic flow, as well as add new signs, drainage and pavement markings. A Route 228 overpass also is to be replaced.Initial construction contracts were awarded Feb. 25 and construction is expected to cost more than $10 million.PennDOT has scheduled construction of the northbound on-ramp for 2011 and the southbound loop ramp for 2012.