The demolition of the Laurens Street bridge has begun.Work, performed by Crowder Construction, started Wednesday to replace the bridge that has been closed since early April 2 after the southwestern corner began to sink, making it unsafe for vehicles and pedestrians.The demolition will take about three or four days to complete. According to Jeff Terry with the S.C. Department of Transportation, this is a controlled demolition since there is an active Norfolk Southern railroad track underneath the bridge. Slabs of concrete are being lifted off the bridge by a crane and disposed of rather than just demolishing it all at once, which would lead to debris falling onto the tracks."It's kind of like when you build a Lego bridge, you just knock it over and just sweep the pieces back into the box," Terry said. "In this case, you're taking it apart Lego by Lego."Crews are carefully working around the schedule of the one train that travels that track.According to SCDOT, the bridge should be finished and open to traffic by Sept. 28.The cost of this replacement project is approximately $2.5 million. The bridge was considered eligible for federal Emergency Relief funding, which includes a 100 percent reimbursement of federal funds for all repair and replacement work that occurs within the first 180 days, according to SCDOT.If the work isn't complete within that time period, the federal contribution would drop to 80 percent, and SCDOT would be responsible for picking up the 20 percent of the remaining cost.The 180-day countdown started on April 10, when Gov. Nikki Haley signed an executive order declaring that an urgent situation existed at the bridge, approving the Emergency Relief funding.While work is under way, the construction area will be fenced off on the north side of the bridge from the Christ Central driveway to the center median, and the southbound lane of Laurens Street will be two ways for the half block from the Christ Central driveway to the median cut through at Hoods Lane during construction, according to the City of Aiken.Amy Banton is the city beat reporter and has been with the Aiken Standard since May 2010. She is a native of Rustburg, Va., and a graduate of Randolph Macon Woman's College.