PROVIDENCE -- The installation of a set of huge steel girders across Route 95 as part of the relocation of Route 195 will mean a series of nighttime closures of the highway, the state Department of Transportation said yesterday.

The closings will take place July 29 and continue on Sunday through Thursday nights through Aug. 12, the DOT said. The closings will affect the highway’s northbound or southbound lanes, or both, between Exits 18 (Thurbers Avenue) and 20 (Route 195 East).

As in the similar closings in April and May, the DOT has laid out an elaborate system of detours. This one provides for the diversion of traffic northbound and southbound on Route 95 and westbound on Route 195 at various times and in various combinations, plus detours for rescue vehicles headed to Rhode Island Hospital. The plan is complicated enough to require three maps with eight colors and three kinds of dotted lines to show the detours.

Officials say they will use five overhead message signs and 12 portable message signs to notify drivers of the detours. Maps are available on the DOT Web site, www.dot.state.ri.us. Phone information will be available by calling 511 or 1-888-401-4511 for out-of-state callers, on the DOT’s advisory radio channel at 1630-AM, and through the DOT’s customer service line at (401) 222-2450.

The closures are set to allow the contractor, Cardi Corp., to install tub girders, the long, box-like steel beams that will support the highway deck. The DOT said this phase of the project would involve placing 61 of the girders, weighing between 13 and 47 tons, on concrete piers already built along Route 95. Yesterday, cranes were lifting some of the girders into place along the highway near Rhode Island Hospital.

The work is part of a $55-million contract with Cardi Corp. to build ramps over and near Route 95, connecting Route 95 southbound with the new Route 195 eastbound, and Route 195 westbound to Route 95 northbound. That contract, in turn, is part of the massive, $577-million project moving a portion of Route 195 and its interchange with Route 95 south from its present location. The project’s most visible element is the new steel arch bridge across the Providence River.

“All construction that impacts traffic will be done during the overnight hours,” DOT Director Jerome F. Williams said in a written statement yesterday. “Our goal is to make phase two run as smoothly as phase one did this past April and May.” The DOT said that the work depends on the weather and that the schedule may be changed or extended.

Eddy Street in Providence will be closed for three evenings beginning Wednesday from 9 p.m. to 6 a.m. and again on three nights beginning Aug. 7 so crews can install girders over the roadway, the DOT said. Eddy Street will be closed between its intersection with Allens Avenue and Eddy Street and Crary Street just south of Route 95. The DOT said detours would be arranged, and wouldn’t affect traffic to the hospital.

Before the closures, state police will conduct “brief rolling road blocks” after midnight on Route 95 between Exits 18 and 20 in Providence to allow cranes to move across the highway into position to install the beams. That will delay northbound traffic July 22 and southbound traffic July 23. Officials said state police cars driving abreast in all of the lanes will slow down together, beginning some distance away from the work site, forcing traffic to slow down and allowing up to 20 minutes for the cranes to cross the highway. Some highway lanes may be closed to prepare for the maneuver, the DOT said.

The full closures of Route 95 will start July 29 in the southbound lanes. In a procedure similar to the one the DOT used in the spring, the agency said it would start closing lanes at 8 p.m., with all lanes closed by 11 p.m.

“All lanes will be reopened by 5:30 a.m.,” the DOT said.

“One to two beams are expected to be set each night and, once again, motorists will see a new landscape each morning as they head into Providence,” Williams said.

For about two weeks in mid-August, beams will be installed above Allens Avenue in Providence from the intersection of Eddy Street and Allens Avenue to Public Street. The road will be closed from 7 p.m. to 6 a.m. and local detours will be in place, the DOT said.

During the closures, the DOT wants drivers to use Route 295 as a detour if they are not headed into the Providence metropolitan area. Drivers who need to get around Providence itself should use Routes 6 and 10 or follow the local detours. Drivers headed for the Rhode Island Hospital complex will be able to follow signs bearing a blazing blue “H” through local streets.

The DOT expects to open the first part of the new interchange, the ramps carrying traffic from Route 95 north to Route 195 east, by the end of the year, Frank Corrao III, the DOT’s deputy chief engineer, said.

The DOT chose the Point Street overpass over Route 95 to announce the work and detours yesterday.

The overpass offers a view of the work site. It is also, however, something of a monument to troubled DOT projects. Providence-based Shire Corp. was low bidder, at $9.6 million, in February 2002. Construction began March 13 and was supposed to be complete 20 months later. But the overpass took more than 4½ years to finish and is expected to cost slightly more than $17 million, more than $7 million over the bid price, according to DOT figures. The increase includes a $3.1-million settlement with the contractor because of design problems that caused expensive delays.

“That is a totally separate issue,” Corrao said yesterday. “The impact to the 195 project from that was minimal.”

blandis@projo.com