CONSTRUCTION–RECONSTRUCTION DILEMMA

CONSTRUCTION–RECONSTRUCTION DILEMMA

Jack Lettiere, highway administrator for New Jersey DOT, commented at the 2005 North Carolina DOT/Consulting Engineers Conference on the importance of transportation to our citizens. “Transportation is the game board on which everything is played—getting children to school, folks to work, freight delivery, etc. Imagine the impact of reduced congestion on family life and community service. Fifty million Americans are homebound by virtue of lack of transportation. Imagine the cost to our productivity.”

Lettiere mentioned the efforts by highway agencies to engage the American public in the infrastructure needs of the highway system: to be willing to fund necessary maintenance, rehabilitation, and reconstruction. This has included discussions on the number of miles of poor condition pavement, the number of deficient bridges, and even the number of fatalities caused by pavement conditions. The public has not responded to any of these appeals. To what have they responded? According to Lettiere, the public has responded to project delivery. The public wants transportation agencies to deliver projects in a timely manner with minimal traffic impacts. There is risk associated with these projects because they require agencies to try new methods and materials, but it is a risk that we must take.

An example of such a high-risk project was the reconstruction of the Tappan Zee Toll Plaza by New York DOT. Because of traffic requirements, the contractor was required to be off the roadway every morning by 6 a.m., with a $1,300 per minute liquidated damage if not. The agency selected to use prefabricated concrete panels for the roadway reconstruction. Each panel was carefully measured; detailed survey controls as well as manufacturing controls were enforced ( Figure 4 ). Once the panels were constructed and cured, sawing of the joints was done at the plaza on the night before reconstruction. As soon as traffic control was in place, the

FIGURE 4 Precast concrete panel for Tappan Zee Toll Plaza reconstruction.

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sawed slabs were removed to flatbed trucks and taken off-site. Grading of the subgrade was carefully controlled and select material was placed ( Figure 5 ). Each precast slab was seated, connecting dowels were epoxied into place, and the dowel slots were patched. The progression

of the work is shown in Figures 6 and 7 .

An example that illustrates the risk aspects of alternative methods is the use of reclaiming of Interstate flexible pavements by New Hampshire DOT. Because of the deep frost penetration issues, a dominant form of distress is cold temperature cracking and frost heave. When the flexible pavements reach maximum tolerable distress, they are reclaimed through the full depth of the asphalt, the ground material is compacted, and a new surface course is applied. Figure 8 shows the distress level typical for an Interstate pavement recommended for reclaiming. Unfortunately, New Hampshire DOT has experienced some return of cold weather distress in the form of tenting in some of the reclaimed Interstate pavement ( Figure 9 ). Tenting is differential deflection at a crack caused by moisture accumulating and freezing below the crack. New Hampshire DOT measured tenting of 0.75 in. over a 5-ft straight edge. The department is investigating the causes of the premature failures and is evaluating other alternate methods of rehabilitating pavement in cold environments.