Hydraulic concrete will strengthen the pavement under the 30-ton Metrobuses
By Ivan Sosa
La Reforma, 10/15/2006
Initial Metrobus construction along Insurgentes Avenue
The introduction of hydraulic concrete into the 20 kilometers of confined lanes on Insurgentes Avenue in the Metrobus system will cost 150 million pesos ($14.3 million USD) but will give the lanes a useful life of 70 years, according to Mexico City Secretary of Public Works Cesar Buenrostro.
With this project, he said, the city will avoid the need to repave the lanes every year.
After 16 months of Metrobus operations, the lanes have developed depressions and potholes because the pavement could not support the constant passage of the heavy vehicles which, loaded to their maximum capacity of 160 passengers, weigh up to 30 tons each.
With the deterioration in the pavement, service is slower and the 280,000 passengers transported every day suffer from jolts and jumps inside the vehicles.
Furthermore, the Corredor Insurgentes company (CISA), one of the operating companies for the new public transport system, has had to spend at least 400,000 pesos ($38,000 USD) on repairing and maintaining its articulated buses due to the poor condition of the pavement.
Metrobus invested approximately 600 million pesos ($57 million USD) in buying buses and in confined lanes, stations, and fare collection and monitoring systems, so this new investment will be approximately 25 percent of the initial expenditure.
César Buenrostro explained that between October and December, the first 40 million pesos would be spent on work that would require partial closures of the Metrobus confined lane. “As for the rest of the funds, the new Mexico City Mayor, Marcelo Ebrard, will have to decide when they will be applied,” said Buenrostro.
The sectional closure of the confined lanes will also require the Metrobus stations to be closed, one at a time, between Churubusco-Mixcoac and Eje 4 Sur Xola.
In 1947, hydraulic concrete was added to Paseo de la Reforma Street and “it has lasted for 59 years,” Buenrostro said.
Because of its high cost, the hydraulic concrete will only be applied to the exclusive Metrobus lanes; where other lanes of Insurgentes have cracked or deteriorated, they will only be repaved with normal pavement. In order to set off the space for the hydraulic concrete pavement from the rest of the lanes, a subterranean confinement barrier will be constructed at the subsoil level to separate the two materials.
The vice president of the Panamerican Union of Engineers’Associations, Jorge Jiménez, considers the repair “an expensive investment, but necessary, above all because it will allow the city to avoid interrupting Metrobus service in the years to come.” The results will be lasting, he added, as long as the subterranean structure of hydraulic concrete is constructed “integral with the base, which has a depth of about 40 centimeters.”
Jimenez was critical of the city and Metrobus, saying that the need for more durable pavement could have been anticipated before Metrobus began operating. “That way the inconveniences caused by more road construction could have been avoided,” the expert said.
He added that it would be desireable to incorporate hydraulic concrete throughout the city, although the short-term budget requirements make this infeasible and mean that repaving every year will continue to be necessary.