5 de abril de 2018

CAMBIO CLIMÁTICO : Experimentaran en Phoenix blanqueando el asfalto

No hay texto alternativo automático disponible.

Phoenix.- There is some exciting news in the battle over the Valley’s oppressive heat. Scientists said they were experimenting with using white paint over black asphalt as a way of cutting temperatures. Ronnen Levinson, a scientist with the Lawrence Berkeley Laboratory in California, said it could possibly reduce the heat island effect, a term given to urban areas that are hotter than nearby rural areas. “If you reduce the absorption of sunlight you can lower its temperature,” Levinson said. “That’s the idea behind the cool pavements.”

            The experiment is quite simple: It involves painting black asphalt white. 

 “The tests that have been done so far have usually been done with paints that are some combination of cement and polymer.” In other words, you wouldn’t use a common house paint to cover over asphalt. The experiment with painting over black asphalt has taken place on streets in Los Angeles and parts of Northern California.

Other strategies used in bringing temperatures down in heat islands include planting shade trees and reflecting roofs so sunlight will bounce off.

       Scientists said the big payoff will be energy savings and lower power bills. 

Resultado de imagen para huevos friendose sobre la calle

 Other benefits to cutting the outside temperature include decreasing smog formation and ozone concentration. So far, the cost of painting streets white has not been factored in. “We don’t have an estimate for you on cost,” Levinson said. As for when we could see white painted roads in the Valley’s future, that’s likely years off, as scientists continue to study the urban heat issue.


Mientras, el tramo de la Interestatal 19 frente a Green Valley , sera ahulado para reducir el ruidio de la alta velocidad

Resultado de imagen para fotos de Green Valley arizona

Rubberized asphalt to be reapplied, but how much good will it do? 

 Sahuarita.- When a new coat of rubberized asphalt is laid down on Interstate 19 this year, nearby residents can expect quieter traffic noise. How much? It depends on your distance from the road, whether there are walls, fencing and/or heavy foliage. Even weather conditions can affect noise, said retired aircraft engineer Dick Roberts, who volunteers on various Green Valley Council and Regional Transportation Authority committees. 

 But, factoring that the last rubberized asphalt treatment applied in the late 1990s has worn away, the noise buffering from the new coating is likely to be significant. “Industry research shows that rubberized asphalt reduces tire noise by about four decibels,” said Tom Herrmann, spokesman for the Arizona Department of Transportation.
Resultado de imagen para logo de la Arizona Department of Transportation.
Additional benefits include increased durability and a friction component that makes the road safer by increasing the contact between tires and the road surface. Back in the late 1990s, rubberized road treatment was new to the area, but other states were using it, Roberts said. He heard about it from his dad in Michigan, and asked ADOT if it would consider it. “Basically, ADOT said yes but it's expensive.

But it also lasts longer than other means,” Roberts said. He remembers Sharon Megdal, then with the state transportation board, requesting a presentation about what rubberized asphalt could do for Green Valley. A test strip was laid on northbound I-19 near Valencia Road before ADOT officials decided to try it on I-19 through Green Valley. 

The speed limit then was 55 mph, with resulting noise reduction at about 300 percent, Roberts said. That's according to unscientific research conducted with off-the-rack Radio Shack noise meters purchased by a group of retired aircraft-industry engineers, including Roberts.

They admittedly weren't schooled in traffic noise, but knew a thing or two about abating the din of jet engines. The group selected several points along Green Valley's I-19 stretch to measure sound. Skeptical about the readings on the inexpensive meters, ADOT sent an employee down with their own, more sophisticated equipment and the readings were nearly identical, Roberts said.

He still gets a kick out of telling the story. He and Chet Davis, also from the aircraft industry and residing in Green Valley, were two members of that group. A third, Jim Cole, who as a professional once conducted noise-abatement studies in Chicago, has passed away. But their research still stands and references to it still crop up in GVC and Traffic &Arroyos Committee meetings, most recently after hearing that ADOT is returning later this year to lay a new coat of rubberized asphalt in main I-19 north/south travel lanes.

 Megdal is now director of UA's Water Resources Research Center. While Green Valley's first rubberized coat showed a 300 percent noise reduction, that was cut to about half of that when ADOT raised the speed limit to 65 mph. Still, that left a 150 percent improvement, Roberts said, “a significant reduction.” When the speed limit was raised to 75 mph south of Continental Road, “it took a big chunk of the noise abatement away with the 18-wheelers.” The rubberization project is among other work I-19 is scheduled to undergo this year, or is already in progress. It involves a mill-and-fill (removal of the top surface and replacement with new material) between Canoa Rest Area south of Green Valley, and Duval Mine Road in Sahuarita. 

 Work also includes improvements to the bridge barrier, which is now underway, repaving Esperanza Boulevard under I-19 , and cleaning/repairing the decorative slope paving at Esperanza. Bridge rail and joint work will continue through March. In all, work on Green Valley's stretch on I-19 is expected to take roughly 13 months, an ADOT engineer said earlier in the planning process.

 The first paving is expected along the ridge work in June-July, where metal rails are being replaced with concrete, said James Gomes, regional traffic engineer for ADOT out of Tucson, at GVC's Traffic & Arroyos meeting Wednesday. Preparatory mill and fill work, involving removal of the top two or so inches of pavement surface, is projected to be done in June-August, and the half-to three-quarter-inch rubber coating, in October.


0 comentarios: