Engineers building the massive $1.3-billion Interoceanic Highway are tackling road cracks and unexpectedly difficult site conditions in the second year of work, which began in April as the rainy season ended in the jungles of southern Peru.

In 2004, a consortium of Brazilian construction giant Odebrecht and several Peruvian firms won a pair of contracts worth $892 million for two road sections that run from the town of Urcos, located just outside of the city of Cusco, to the Brazilian border. In all, the consortium Conirsa is building more than 400 kilometers of highway crossing the vast jungle of Madre de Dios province. Another $562-million contract for the 300-km section that runs from the Inambari River to just outside the city of Juliaca was awarded to Intersur, a consortium comprising a similar group of Peruvian companies led by the Brazilian construction firm Camargo Correa.

Overall, the Interoceanic Highway project is divided into five sections, or "tramos." The three currently under construction consist of upgrading more than 1,000 km of an existing two-lane unpaved road that was built more than three decades ago.

C.J. Schexnayder New Peru road sections are built in unstable terrain.

"There has been very good progress, which can be very complicated because of the amount of rain here," says Marcus Felipe, director of the Tramo III project. "That gives us a very short period of time, five or six months, for us to complete 60 kilometers of roadway. We were able to do almost everything." Despite the problems, Felipe says Conirsa is still on track to meet the 2009 completion date.

When completed, the new highway will be 7.4-m wide with two 3-m-wide lanes and a shoulder on each side. The road surface will have a 2.5% incline to permit runoff. The final roadway will be covered with a micropolymer surface in the last year of the contract.

C.J. Schexnayder Crews are fixing cracks in road base before paving it over.

The biggest headache facing Conirsa when work resumed in April consisted of cracks in the pavement, which had been put down just months before. Its contract with the Peruvian government required Conirsa to pave at least 60 km of the roadway in the first year of work. The team chose to concentrate paving efforts at the farthest point of the highway, between its base camp in the town of Iberia and the Brazilian border.

In April, engineers discovered that samples taken of the base began to exhibit micro-cracking, a problem that soon was evident in the roadway itself, says project engineer Winston Villagomez. A team of Brazilian and Peruvian engineers came in to examine the situation and determine if the cracks presented a structural hazard. They concluded that the heat and winds common in the region cause a rapid rate of evaporation, which led to the cracking. "According to the experts we brought in, the problem is not growing," Felipe says. "In principle it is possible that the situation has stabilized. But we have observed there are times when the cracks appear in a period of days, and at other times, they appear months later."

The problem stems from a lack of aggregate available for use on the far side of the Madre de Dios River. Crossing the river is a logistical nightmare since there is no bridge spanning the half-mile-wide waterway. Peruvian officials have begun construction on such a crossing-the $15-million, 719-m-long Guillermo Billingurst Bridge-but the project is not expected to be completed until after the roadway is built. For now, Conirsa relies on a ferry, the Interoceanica II, to transport equipment and supplies across the river.

The road's sub-base is 20 centimeters thick and consists of lime mixed with prepared material. It is topped with a 20-cm-thick base that, in the absence of sufficient aggregate, consists of a cement and soil mix. The paved roadway itself consists of two layers of asphalt, each 2.5 cm thick. "The cracks do not impair the integrity of the cement," Villagomez says. "It isn't a structural issue for the roadway itself."

The initial solution has been to seal the cracks with liquid asphalt that has been mixed with an elastic polymer. Currently, the cracks are being sealed as they manifest themselves in the base, prior to the application of the first layer of asphalt. The proportion of cement in the base and the proportion of lime in the sub-base have also been changed to alleviate the problem.

C.J. Schexnayder Construction traverses jungle area of Peruvian province.

While Conirsa's contract with the Peruvian authorities requires the completion of a certain percentage of work on the roadway each year, there are no more paving requirements. That gives the consortium significant leeway in terms of solving the problems and finishing the roadwork by the 2009 deadline.

Shaky Slopes

Another challenge has centered on the difficult geography near the Inambari Bridge site, where Conirsa's two road sections will connect. Much of this region ranges between 2,500 and 1,000 m in elevation. The terrain is marked by lush vegetation, steep slopes and almost daily rainfall during half of the year.

These conditions will require extensive preparation work. Multiple levels of terracing built above the roadway as well as supports below are needed. The abundance of runoff also places a premium on drainage works and bridges. Many of the sections have proven susceptible to landslides. Several of these have struck vehicles using the roadway in the evenings it is open for public use, causing at least two fatalities.

Much of the actual geography and soil conditions turned out to be significantly different from the information provided to Conirsa by the Peruvian government. Wilhelm Funcke, the head engineer for Intersur, said last year that his engineers encountered similar problems in that firm's section of Tramo IV near the Inambari Bridge.

The complex geographical hurdles are complicated further by the need to keep the highway operational. Conirsa, for example, has begun shutting down the road intermittently during daylight hours to do work. This, as well as the additional time needed each day for cleanup, severely cuts into the rate of progress. To better deal with the situation, Conirsa has consolidated its efforts by creating a "Tramo Central," which incorporates a portion of both sections. "This way we are not duplicating the effort and we can focus on addressing this complex hill work more directly," Felipe says.

The last two sections of the project include the upgrading of more than 1,500 km of existing paved roads that lead to three coastal cites in southern Peru. The two contracts, valued at approximately $235 million, are expected to be put out for bid in August, according to officials with ProInversión, Peru's state agency for promoting private investment. Initially, the final two sections were slated to be put out for bid last November. According to officials with the MTC, the subsequent delay was due to the complexity of the tender process and modifications made to the project's tender rules that were made to ensure high-level, competitive bidding.

When complete, the project will create the first paved roadway connecting the Atlantic and Pacific oceans across the South American continent.

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