Pavement in depth

June 6, 2007

Paving on the new Dan Ryan expressway was moving at a good pace on the May day when Roads & Bridges visited the site. Near 59th Street, haul trucks were lined up to deliver fresh concrete to a conveyor on a GOMACO placing machine. The placer roughly spread the concrete mix across the 24-ft width while the GOMACO paving machine following behind formed it into a neat slab 14 in. thick on the expressway’s northbound local lanes, which run from 71st Street to 26th Street.

Paving on the new Dan Ryan expressway was moving at a good pace on the May day when Roads & Bridges visited the site. Near 59th Street, haul trucks were lined up to deliver fresh concrete to a conveyor on a GOMACO placing machine. The placer roughly spread the concrete mix across the 24-ft width while the GOMACO paving machine following behind formed it into a neat slab 14 in. thick on the expressway’s northbound local lanes, which run from 71st Street to 26th Street.

A work bridge then dragged Astroturf over the fresh concrete slab to give it some roughness for increased traction. The next GOMACO machine came along and tined the concrete, putting 1/8-in.-deep grooves into the surface for greater traction in wet weather. To reduce the noise of tires slapping the grooved pavement, the grooves are set at varying intervals and skewed at a 15° angle from the transverse, so they are not quite perpendicular to the direction of traffic. The tining machine periodically backed up and sprayed a curing compound on the newly tined pavement to seal in the water needed for the hydration reaction that gives concrete its strength. “We’re pouring out here at about 250 cu yd an hour,” Pat Goggin, operations manager for Walsh Construction, told Roads & Bridges, “so if you’re pouring 24 ft wide,” Goggin said, the paving machine moves at about 250 ft an hour.

The concrete mix was being trucked from a batch plant on 43rd Street between State and Federal. The plant was so close, the mix could be carried by haul trucks rather than mixer trucks.

Most of the concrete has been supplied by Prairie Material Sales Inc., Ozinga Bros. Inc. and Aztec Material Service Corp., said Goggin. K-five Construction Corp. and Gallagher Asphalt are supplying the asphalt mix. The epoxy-coated steel reinforcing rebar is being supplied by Steppo Supply & Construction Inc. and Mosley Construction. Those are just a few of the contractors working on the project.

Traveling north up the expressway was a little like going back in time. There was a section of continuous rebar waiting for concrete to be poured over it. There was exposed asphalt waiting for rebar to be set up on top of it. At the north end were excavators digging for the revised drainage system. The drainage system includes 198,000 linear ft of pipe, most of it concrete, ranging from 12 to 54 in. in diam., 236 inlets, 3,400 catch basins and 963 new manholes.

IDOT needed to fix the drainage system because there were problems with flooding along the expressway.

“There’s a deep tunnel that runs adjacent to the CTA tracks,” Eugene Joynt, bureau chief of construction for the Illinois Department of Transportation (IDOT), explained to Roads & Bridges. “Our drainage would go into the CTA drainage and then into the deep tunnel.” After experiencing flooding problems along the Dan Ryan, IDOT decided to fix the problem during the expressway’s reconstruction.

“We isolated our drainage system from the CTA system, so now we have our own connection points to the main drain storm sewer,” Joynt said. “That was a pretty substantial cost. We jacked pipes underneath the expressway and built junction chambers.”

In fact, IDOT had the contractor jack into place over 6,800 ft of storm-sewer pipe and over 3,800 ft of water-main pipe.

“Rather than digging a trench and installing it, they just jack it right straight through until it gets to the point where they want it,” said Goggin, “and then they drop another shaft and hook it up.”

Alongside the excavators were bulldozers using their GPS receivers to push earth and prepare the bare ground to within about an inch of the design grade.

Design in depth

In a sense, the old Dan Ryan is forming the base for the new Dan Ryan. The old concrete is being hauled to a crushing plant at the same yard where the new concrete is mixed. There the old concrete is smashed into small pieces and then hauled back to the construction site and used in the 21-in. sub-base of 6-in.-minus porous granular embankment. On top of the sub-base is 3 in. of capping, which is made up of either the grindings of the asphalt overlay that was on the old pavement or CA6 stone.

Over the whole length of the Dan Ryan project, which runs between 13th Street and the I-57 interchange, IDOT will lay about 70,500 truck loads of sub-base. About 445,500 tons of hot-mix asphalt (HMA) will be sandwiched between the sub-base and the concrete surface pavement. And the crews will lay 123 lane-miles of continuous-reinforced-concrete pavement, enough for a one-lane road from Chicago to Madison, Wis.

Under the sub-base is a sheet of geofabric. “The geofabric liner keeps the soil from migrating into the stone, so you have a uniform base,” said Joynt.

On top of the capping is 6 in. of HMA to give the pavement just a bit more flexibility than all-concrete pavement would have. To top it off is 14 in. of continuous-steel-reinforced concrete with the reinforcing bars spaced 5.25 in. apart.

The original Dan Ryan Expressway was built in the early 1960s, opened to traffic in 1962 and named after Daniel B. Ryan Jr., who was a Chicago insurance broker and served as president of the Cook County Board of Commissioners from 1954 until his death in 1961. The original expressway was built to last 20 years and carried 150,000 vehicles a day in 1963.

The result of completely reconstructing the Dan Ryan for the 21st century instead of restoring it to its 1962 condition is that the travelers in the 300,000 vehicles that use it every day get an expressway that should last 30 years and should be safer than the old Dan Ryan, which had the most crashes of any expressway in the Chicago area.

Greater safety is the good news. The bad news is a higher price. Building a 30-year pavement instead of a 20-year could boost the cost of the Dan Ryan Expressway reconstruction to almost twice as much as first estimated.

Then and now

The original cost estimate in a 2000 plan for rebuilding the Dan Ryan Expressway to its original form was $550 million. The latest estimate of the cost of reconstructing the expressway to 21st-century form with an added local lane in each direction between 47th Street and 95th Street is $975 million.

IDOT’s goal for work performed by disadvantaged business enterprises (DBEs), companies owned by minorities, is 23%. They are pretty close to that target, said Joynt. The project’s DBE participation is as high as it is because IDOT split up the reconstruction work into more than 40 smaller contracts, so more small companies would be able to compete for them.

“To date, we’ve let $793 million worth of contracts for construction,” Joynt reported.

Another reason for the ballooning cost, according to Joynt, is materials inflation. The cost of construction materials has jumped dramatically in the past couple of years. Crushed stone, steel, concrete, asphalt and fuel costs all have grown significantly more expensive, especially in recent months.

Change orders, which drive up the cost of some projects, are not a big factor in the case of the Dan Ryan, the Chicago Tribune reported. Necessary extra work not anticipated in the original contracts has been held to just 4.2% of the project.

Still, most of the big contracts went to Walsh Construction Co., a Chicago-based giant. Walsh this year is performing the bridge deck overlay job from Roosevelt to 26th Street, four local-lane contracts and four south mainline contracts. Last year, Walsh paved the express lanes, which are in the middle of the Dan Ryan Expressway but outside of the Chicago Transit Authority’s (CTA) Red Line rail transit.

Ozinga is supplying a complex and demanding concrete mixture for an overlay on the Dan Ryan’s elevated bridge, which goes between 15th Street and 31st Street. The mixture contains micro silica and 90/40 strux fibers to increase strength and resistance to impact. Ozinga said the high-strength, impermeable concrete mix is so complex that it is tested by Ozinga at the plant and by Walsh and IDOT in the field.

To provide an incentive to complete work early, IDOT is offering $10,000 per day for early completion of the section from 71st Street to the I-57 interchange; $12,500 per day for early completion of the local lanes; and $20,000 per day for early completion of work on the elevated bridge. These jobs are scheduled for completion on Oct. 31.

Along with improving the drainage system along the expressway, adding a lane in each direction will eliminate traffic bottlenecks, reduce congestion and improve safety, according to IDOT. Other improvements include reconfiguring ramps to improve traffic merges and reduce weaving in traffic, both major causes of accidents on the roadway. In the new design, the entrance and exit ramps are longer, allowing more time for drivers to merge.

In its final configuration, the Dan Ryan will have four express lanes and three local lanes in each direction for its entire length.

Higher barrier walls along the CTA transit line will prevent errant cars from landing on the tracks.

A full interchange will be constructed at 47th Street by adding a northbound exit to 47th Street and a southbound entrance from 47th Street.

An additional 236 high-mast light towers with 1,500 luminaires will improve visibility on the expressway, and 13 new dynamic-message signs will offer more traffic information to motorists. To supply more traffic information to IDOT, the agency is installing 16 closed-circuit television cameras and 25 traffic-detection loops.

At the south end of the project, IDOT constructed four bridges as part of the Skyway interchange and reconstructed the I-57 bridge over the westbound connector.

Goggin said one of the challenges of the Dan Ryan work was making sure the construction activities were coordinated with the CTA requirements. Walsh also has to coordinate its construction with the White Sox baseball games, which are played in a stadium right next to the expressway at 35th Street.

“The major significant challenge is the amount of work, the amount of material, the quantity of all the different pay items that have to be done in such a short period of time,” said Goggin, “as well as the amount of traffic that we have to deal with.”

IDOT’s efforts to reduce traffic congestion during the reconstruction worked well last summer, the first season of Dan Ryan reconstruction. IDOT started early publicizing the lane reductions on the expressway. The agency advised drivers to divert to other north-south routes to avoid jamming up the construction zone. During last summer’s construction season, vehicle counts dropped from the usual 300,000 a day to 200,000 a day, according to Mike Claffey, public information officer for IDOT.

The Dan Ryan Expressway reconstruction is scheduled to be completed in November of this year.

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