A crane prepares to install a section of one of the Clifford Street beams over Route 95 on Sunday night, temporarily closing the interstate highway in both directions. Work on the overpass was scheduled to continue on both Monday and Tuesday.

The Providence Journal / Kris Craig

PROVIDENCE, R.I. — The latest element to pop up on the state Department of Transportation’s Route 195 project has been a new bridge over Route 95, connecting Clifford Street in the city’s Jewelry District on the east side of the highway with Friendship Street on the west.

As anybody driving on the interstate highways here knows, things have been moving around as the state Department of Transportation relocates the interchange where Route 195 meets Route 95.

Until recently, most of the work, such as the new section of Route 195 and the new bridge across the Providence River, took place off the existing highways, and drivers could watch from a safe distance.

But now, the DOT is connecting new with old. There are new stretches of highway, new ramps, ramps moved and ramps closed altogether.

Although DOT engineers say the changes are the result of years of planning, the changes often have no obvious cause and can seem like random annoyances, but they can also be strikingly interconnected.

One of the project’s most noticeable developments was the temporary “split” the DOT installed on the morning of June 18 at the extreme eastern end of the project.

Built at the Providence side of the Washington Bridge, it affected every driver entering the city from the east –– roughly 85,000 of them per day. It divided westbound traffic into two streams, one for Route 95 north and the other to the south.

It also caused traffic congestion, which DOT Director Michael P. Lewis had predicted, forced thousands of drivers per day to cut across heavy traffic on the bridge to get to Route 95 southbound, and cut East Side residents off from highway access to Route 95 south.

Frank Corrao III, the DOT’s deputy chief engineer in charge of construction, said that the split was needed because of the work on Route 95 and on the links between that road and the new section of Route 195.

That’s at the opposite end of the project, more than a mile away from the split at the Washington Bridge. It couldn’t be much farther away and still be in the project. The location is near the new Clifford Street Bridge over Route 95. Recently, the DOT closed Route 95 at night to put up the bridge’s beams.

The problem on the west side was largely caused by the old Route 195 ramp to Route 95 south, now demolished, which was in the way of both the relocation of Route 95 and the construction of new ramps to Route 95 north.

Corrao said that the piers for the old ramp’s overpass stood right where the northbound side of Route 95 was to be built, and the ramp blocked completion of a new ramp connecting Route 195 to Route 95 north.

Corrao said that Route 95’s northbound and southbound lanes were built with space between them to allow the construction of two ramps in between, one a left-hand exit from Route 95 south to Route 195 east and the other a left-hand entrance to Route 95 south from Route 195 west.

Left exits and entrances are considered a bad arrangement because they mix traffic slowing down or speeding up for ramps with traffic traveling fast in the high-speed lane.

The DOT has moved those ramps across Route 95’s southbound lanes, putting them both on the right side of the highway, and moving them south to the new interchange. It also moved Route 95’s northbound and southbound lanes together, to leave more room on both sides of the highway for new ramps and extra lanes.

The result was that the new Route 195 ramps to Route 95 north could not be built at the same time as the ramps to Route 95 south. That meant that the traffic for each had to be separated somewhere else.

There’s nothing obvious connecting the cause of the problem –– the old Route 195 ramp to Route 95 southbound –– with the temporary cure, diverting traffic at the Washington Bridge.

The split ended up at the west end of the Washington Bridge for two principal reasons.

First, it couldn’t be moved any farther east, which would have put it in East Providence.

A large amount of westbound traffic from Taunton Avenue and Veterans Memorial Parkway enters Route 195 at the East Providence end of the bridge. Putting the split east of that would have meant unworkable detours, Corrao said.

On the Providence end of the bridge, the split’s location was affected by a pair of 48-inch storm drains that cross under Route 195 just west of the new pedestrian bridge.

They drain storm water from a sizable portion of the East Side, so shutting them off wasn’t possible. The DOT needed to divide traffic, partly to shift the highway out of the way while it replaced the drains. By the numbers

$610 million

Estimated cost

1999

Design complete

2003

Major construction begins

Oct. 22, 2009

Last of major elements complete

2012

Project completion