Vans With Lasers Are Telling Engineers Which Roads to Fix FirstJennifer Oldham
The white Ford van rumbled down Devonshire Avenue, past the green-trunked palo verde trees and graveled lawns of central Phoenix. Lasers up front mapped the road’s roughness, and high-definition cameras on spider-like arms in back recorded continuous images of cracked asphalt.
With 65 percent of U.S. roads rated in less than good condition, cities and states no longer leave funding decisions to intuition and influence. Instead, they use data vacuumed up by arachnid-armed “spider vans” with bulbous cameras and global-positioning equipment protruding from roofs. Six computers inside Phoenix’s four-ton vehicle stored data for engineers to download.
“Our roads are in pretty tough shape,” said Mark Glock, the city’s deputy street transportation director. “Our annual budget is $23 million. We are on a 65-year cycle and we know pavement only lasts 35 years. We’re very limited in our treatments.”
About 20 transportation departments from Seattle to South Dakota to Connecticut are deploying vans sold by a unit of Fugro NV to triage work and stretch budgets. These departments, together with others using systems made by a handful of competitors, use the data to comply with new federal rules requiring states to survey roadways and set targets for improvement.
The push to resurface roads comes as Congress dithers over refinancing the depleted Highway Trust Fund. The latest of 33 short-term extensions to the fund since 2005 runs out July 31.
Arizona receives as much as 29 percent of its money for highways and transit projects from the fund, four percentage points above the U.S. average, according to a February report by the Pew Charitable Trusts. In other states, the situation is more dire. Twelve rely on it for 37 percent or more, including Montana, North Dakota, Mississippi, Georgia, Vermont and Rhode Island.
Improving the condition of the country’s highways and bridges will cost $120 billion between 2015 and 2020, while current spending at all levels of government is just $83.1 billion, according to the U.S. Transportation Department.
“The system is falling apart,” said Kirk Steudle, director of Michigan’s Transportation Department, which deployed such vans to determine that the state’s 120,000-mile (193,122 kilometer) road network needs at least $1.2 billion in improvements. “The Highway Trust Fund isn’t providing enough revenue and there isn’t even any political will to address the issue.”
In Phoenix, where complaints pour in about triple-digit heat cracking roads, funding from the state for street work has declined 30 percent since 2007. Before the city purchased its van in 2008, citizens who complained loudest often got their streets resurfaced first.
Today, engineers apply data and images of the city’s 5,000-mile street network to create digital color-coded maps that rate conditions from good to poor. They used the ratings to devise a five-year maintenance plan.
“We didn’t have a comprehensive grasp of the condition of every road and street,” said Rubben Lolly, a city engineer. “Now we have the business to tell residents, ‘Your road is in a condition to wait because there’s someone with one that’s in worse shape.’”
Using a range of sensors, the spider van measures an assortment of pavement characteristics, including detailed imaging of the road’s surface for rutting, roughness and other defects.
Engineers analyzed Devonshire Street, which last received a new surface in 2001, using information recorded by the van’s sensors. Lasers measured its roughness level as poor. Its numbers were then weighed against the condition of other streets and the time since it was last repaired.
Despite its surface like alligator skin, Devonshire was classified in good condition overall, scoring 67 out of a possible 100 points, two above fair. It’s due for its next overhaul in 2018.
Data collected by systems mounted on Fugro’s vans, which recorded images on VHS tapes when they were first deployed three decades ago, help officials prevent damage as well as fix existing flaws, said DJ Swan, a Toronto-based senior pavement management engineer with the company. Engineers can pull up historical images on mobile phones.
“Pictures show us when a crack first appeared and how it changed,” Swan said. “We know exactly why roads are failing and what we can do to prevent the failure -- it’s cheaper to do it that way.”
Such detailed measurements have been used across the U.S. to save money, overcome opposition to tax increases and to assist after natural disasters.
The maps proved critical to persuading the Phoenix City Council to place a measure on the Aug. 25 ballot asking voters to increase the sales tax to 0.7 percent from 0.4 percent in part to fix and repair roads.
Legislators in South Dakota voted to raise the gasoline levy by 6 cents a gallon in April -- the first jump in 16 years -- after Republican Governor Dennis Daugaard in a January speech displayed pictures of rutted roads taken by his spider van. The vehicle travels the state’s highways six months out of the year to catalog craters caused by freezing and thawing.
“Our roads are, by far, our state’s most valuable physical asset, worth over $14 billion,” Daugaard said. “Our entire economy, indeed our very well-being, depends on road infrastructure. And right now, our roads are underfunded.”
Darin Bergquist, secretary of the state’s transportation department, said the pictures told the story.
“Any time you can go to the legislature with objective data, as opposed to subjective opinions, that really helps,” he said.
Louisiana used images from a van after Hurricane Katrina to make a case for additional federal funding to repair damage and crews there recently collected another 90,000 miles of data.
Connecticut’s Transportation Department created catalog of cracking and roughness. Engineers can log onto a computer, select a year and “drive” down byways, said Kevin Nursick, a spokesman.
“We used to have to go out to a site to see if signs were missing, but now we can look on the digital highway and see if they’re there or not,” he said.
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