As interstate highways throughout the U.S. reach the end of their natural life cycle, new and innovative pavement design techniques are being employed to rebuild these vital roadways.
On I-190, general contractor Oakgrove Construction Inc. of Elma, N.Y., insisted from the start on recycling 60,000 cu yd of the 40-year-old concrete pavement because it was cost effective and provided a hard 1-ft layer of subbase for the reconstructed roadway. It was just one of several decisions and ideas that turned the project into a unique and successful effort.
Bring in the replacement
The Niagara Thruway (I-190) Project was a 4.3-mile, $48.3 million total reconstruction of the Niagara Section of the New State Thruway, from Ontario Street in the city of Buffalo and running along the Niagara River.
The Thruway continues through an industrial area in the town of Tonawanda, connecting to the I-290 interchange and heading north, where it terminates just past the toll plaza south of the Grand Island Twin Bridges. The industrial area consists of the General Motors-Powertrain Division Engine Plant, the E.I. DuPont DeNemours Plant, the Dunlop Tire Corp. and several other major manufacturing facilities.
The Niagara section consisted of the removal and full-depth replacement of the 40-year-old concrete pavement and subbase. The project also included the complete reconstruction of six bridges that carried the main-line Thruway over Sheridan Drive (Route 324), Kenmore Avenue, two Conrail lines and Grand Island Boulevard.
The reconstruction and full-depth pavement replacement included 48,000 cu yd of 11-in.-thick N.Y.S. DOT Class C concrete on the main line, along with 14 ramps, a toll plaza and 4,000 cu yd of N.Y.S. DOT Modified Class F Concrete.
The typical southbound section of the main-line Thruway consisted of two lanes totaling 24 ft wide. The northbound section varied from two to three 12-ft-wide lanes in three separate areas and widened up to six 17-ft-wide lanes at the toll plaza, then narrowing back down to two 12-ft-wide lanes to meet the South Grand Island Bridges. The shoulders were constructed with asphalt, and the median was constructed of slipformed concrete barrier.
A 20-month labor
Construction began on this project on April 7, 1998, and was completed on Dec. 10, 1999.
The scope of work for Leone Construction Inc. of Cheektowaga, N.Y., was to pave the 11 in. of concrete pavement on top of 4 in. of cement-treated permeable base.
The placement of the concrete was done with a Gomaco 2600 Spreader at a 24 ft width. This machine also inserted the 20-in. epoxy coated bars 36 in. on center.
A CMI Suburban paver was used to consolidate and extrude smooth pavement. A modified Bid-Well 4800 was used for texturing and curing.
Concrete was batched off-site at a central mix plant provided by Pine Hill Materials Corp. Double string lines were utilized to ensure a precise line and grade. Intermediate pins were placed at 25-ft intervals on tension sections and 12.5-ft intervals at radius sections.
The project specifications called for the use of a California Type Profilograph to measure the finished pavement surface smoothness. The Maximum Profile Index was 7 in. per lane mile on a 2/10 Blanking Band. All of the concrete pavement placed, including ramps, tapers and conventional formed concrete, received an incentive bonus of 103%.
Four lanes (two lanes northbound and two lanes southbound) of traffic had to be maintained at all times. While the southbound lanes were being reconstructed in 1998, traffic was diverted to the northbound lanes by utilizing the widened median and outside shoulder. This setup was reversed the following year while the northbound lanes were reconstructed.
Checking the index
Providing well-maintained equipment was an important aspect of this project.
The average profile index for the main-line pavement was between 1 and 3 in. per mile. However, the specification for this project called for all of the concrete pavement to be profilographed, including ramps, tapered sections, 10 traffic detoured crossovers and the toll plaza area. These special areas had to be poured in the conventional manner with rigid steel forms and were finished with a triple Tube Roller. As a result, the average profile index in these smaller and uneven areas brought the overall average profile index to ±.5 in.
The specification also called for 6.45 miles of the new pavement that ran through a residential area to be fully diamond ground for noise reduction. Safety Grooving and Grinding (SG&G) of Napoleon, Ohio, diamond ground and textured the roadway. SG&G had to meet specs of 7 in. per mile on a 0.2-blanking band. The average profile index for this section prior to grinding was 1.9 in. After the diamond grinding was complete, the average profile index was 0 in.
The quest for quality
There was close monitoring of the concrete as it was batched to ensure that the slump was maintained between 1.0 and 1.5 in. and the air content at 6% ± 2%.
Because of limited space on the project site, the Pine Hill Materials batch plant had to be located in excess of a mile off-site. It was very important to maintain communications at all times with the batch plant. Due to temperature changes and wind conditions, the slump and air had to be adjusted accordingly throughout the day.
Concrete was delivered to the site on dump trucks. Because of lack of space, the dump trucks utilized a very narrow haul road. In three instances, no haul road could be constructed. As a result, the dump trucks had to back up on top of the permeable base, a distance of approximately 2,000 linear ft, to deliver the concrete to the placer. The transverse joint baskets were then placed as the paving progressed.
To ensure proper depth of the concrete, Leone Construction incorporated 4-in. x 4-in. x 1/16-in. steel plates that were fastened every 200 ft at 2 ft inside the edge line on top of the permeable base. After the paver passed over, the inspection team measured the depth of the concrete with a steel rod equipped with a gauge set for 11 in., the specified depth of the concrete. This method of testing the concrete depth was an experiment Leone Construction introduced on this project. It is hoped that in future projects this method will be used in lieu of coring the concrete pavement to determine depth. On this project, a core test was taken and the results were compared against the results from the rod measurements. The core test results were found to be identical to the rod measurements.
In some specific locations, Modified Class F concrete was placed. The specification slump from 1.5 to 2 in. was reduced to 1 to 1.5 in. Joint spacing was at 18-ft intervals, with longitudinal joint ties spaced at 36 in. on center.
The N.Y.S. DOT concrete mix design for Class C concrete called for 605 lb of cement, 1,085 lb of sand and 1,855 lb of a blend of course aggregates, No. 1 and No. 2 stone per cubic yard, plus water, an air entraining agent and a water reducer.
The concrete mix design for the N.Y.S. DOT Class F concrete consisted of 715 lb of cement and the same ratio of aggregates as in the Class C.
However, a Modified Class F concrete was called for in the specifications. This mix was to achieve a strength of 3000 psi in 24 hours. It was left up to the concrete contractor and the supplier to achieve the required strength in the specified time (calcium chloride was not permitted). Leone Construction and Pine Hill Materials accomplished this by using a Pozzutec 20 non-chloride accelerator at 12 to 18 oz. per 100 weight, depending on the daily temperature.
Control joints for the Modified Class F concrete had to be saw cut as soon as people were able to walk on the newly poured concrete. A walk-behind Sof-Cut saw, Model 4000, was used to perform this work. The joints were cut at 3 in. in depth. The concrete was then covered with a curing blanket to retain the heat from the concrete, which at times exceeded 140º F.
The Modified Class F concrete was placed at the toll plaza pavement and at 10 other locations where the traffic was to cross over the closed construction areas.
Over 4,000 cu yd of the Modified Class F concrete were placed on this project, without a single uncontrolled crack occurring.
Working it safe
There was to be absolutely no disruption of traffic during rush hours. Due to the closure of some of the ramps, certain detours had to be established. The New York State Thruway Authority instituted a public awareness campaign to inform the general public on a regular basis throughout this project.
In order to minimize the chance of construction zone accidents, temporary concrete traffic barriers with glare screens and variable message boards were utilized throughout the project. The speed limit throughout the work zone was reduced to 45 mph. There was a strong presence of New York State Troopers enforcing the reduced speed limit.
During certain phases of this project, construction work was limited to weekends only. There was a 52-hour window to excavate, prepare and place the concrete pavement at the north end of the project, near the South Grand Island Bridges, at which time traffic was to return to the new pavement. There were no shoulders available to move the traffic to, and due to the space restrictions, temporary traffic barriers could not be used either. Construction crews were working within inches of live traffic. New York State Troopers were on site at all times during these phases to ensure the safety of the workers and the traveling public.
User delay costs were not considered on this project because, as stated earlier, several crossovers were established throughout the project. Although the crossovers did create some difficulties in constructing the new pavement, there was very little or no inconvenience to the traveling public.
Of special note
As well as being contracted to place the concrete pavement, Leone Construction also was contracted to place over 33,000 linear ft of various types of concrete barrier. To complete this project in a timely manner, they utilized three slipform barrier machines simultaneously, while still placing concrete pavement in other locations.
On the main-line section of the barrier there were over 130 light base structures and a dozen sign structures. Leone Construction fabricated a special hydraulic door in front of the mold of the slipform machine, which allowed them to slipform through rebar cages and anchor bolts which had been pre-set over these structures’ foundations. This innovative technique reduced the amount of wasted concrete and the amount of labor spent for conventional forming.