Will shoulders ease traffic?
STEVE HARRISON
N.C. Department of Transportation engineers recently surveyed a stretch of Interstate 77 in north Mecklenburg and I-485 between South Boulevard and Johnston Road and found the paved surfaces are wide enough to squeeze in an extra lane. There is also enough clearance under the overhead bridges, perhaps the biggest potential obstacle.
Other hurdles remain: The state needs federal approval, which could take several months, and costs are still unknown. Another issue is what happens when a car breaks down when the shoulder is in use.
But drivers welcome the promise of improvement to Charlotte freeways, which are increasingly choked with traffic. Especially maddening is the sea of brake lights filling the southern outerbelt during the evening commute, as traffic heading to Ballantyne and Union County crawls forward on two lanes.
"It's a dead stop," said Jodi Pangia of Monroe, who drives on I-485 at rush hour daily.
The momentum toward using roadway shoulders illustrates how Charlotte and the entire state are struggling to keep pace with growth.
The southern end of I-485 was built in the late 1980s with only four lanes total, in part because computer models underestimated how fast the area would grow. The loop was congested soon after it opened, and today the stretch of I-485 east of I-77 handles roughly 120,000 vehicles daily, making it one of the busiest stretches of highway in North Carolina.
It is scheduled to be widened to six lanes total, but construction on the estimated $65 million project was recently pushed back to 2015 from 2013.
There isn't any money in the current budget to widen I-77 in north Mecklenburg, meaning any construction likely won't occur for eight to 10 years.
Charlotte Mayor Pat McCrory, who has been lobbying the state to use the shoulders until the roads can be widened, told the state's 21st Century Transportation Committee on Wednesday that several European cities are using shoulders without compromising safety. The committee is working to reform the state's transportation system.
"I am cautiously optimistic," said Kevin Lacy, a traffic engineer with the N.C. DOT in Raleigh who is reviewing the initial engineering work.
He believes it's the first time North Carolina has attempted to use shoulders for traffic. Virginia has used shoulders during rush hour on I-66 near Washington, D.C., and other cities are using them for buses or high-occupancy vehicles.
No impediments seen
N.C. DOT said in August it was planning to study the two interstates to see whether there were any "showstoppers" that would prevent the plan from moving forward. Engineers surveyed the expressways in November, and forwarded their findings to Raleigh.Their report: I-485 has a 4-foot inside shoulder and a 10-foot outside shoulder. One possibility is to shrink the regular lanes from 12 feet -- a federal standard -- to 11 feet, creating enough room for a third 11-foot lane.
Motorists here already drive on 11-foot lanes on I-77, between uptown and I-85.
During its analysis, the state found the 4-foot inside shoulder on I-485 was built to the same standards as the regular lanes, but the outside shoulder has 6 inches less asphalt. The N.C. DOT doesn't believe that outside shoulder could handle trucks.
"Maybe we could restrict (the third lane) to autos only," said Curtis Barbee, a transportation engineer with the N.C. DOT in Albemarle who studied the road in late 2007. "But tractors and trailers would tear it up."
The shoulders on I-77 between mile marker 23 in Huntersville and mile marker 30 in Davidson aren't as strong, meaning the state might have to spend money to improve them.
Another concern is bridges. I-485 has three bridges with only two lanes each between South Boulevard and Johnston Road. There is enough room to squeeze a third lane, though motorists would have only inches between their lane and the concrete barrier.
It's possible the state could rebuild the bridges, said Barry Moose, division engineer with the N.C. DOT who oversees Charlotte.
Engineers are worried most about safety, and what would happen if someone broke down when the shoulder was carrying traffic. One possibility would be to create a temporary shoulder to give people a small place to pull over.
Overhead signs?
Another question is how to restrict access to rush hour only. Lacy said the state could install electronic signs over the freeway, with a red "X" indicating a lane is closed. Or it could use road signs informing motorists of when and how the shoulder can be used, similar to an HOV lane.
"How do you sign it? How do you regulate it?" Lacy said. "What happens when there is a breakdown? There are a whole slew of operational issues."
In Virginia, a man was killed in 2000 after he pulled onto an I-66 shoulder that was being used as a deceleration lane for an exit to the Capital Beltway. In a Washington Post story after the accident, an official from the Virginia Department of Transportation was quoted as saying the department had monitored accident rates since converting shoulders for rush hour traffic in the early 1990s, and that they "haven't had an unusual set of conditions occurring that makes us want to revoke the use of shoulders."
Virginia transportation officials couldn't be reached Thursday or Friday to comment on the safety record of the I-66 shoulder project.
Lacy's office is reviewing aerial photographs of the freeways. If he believes it could be done, the next step would be to ask the Federal Highway Administration to modify the interchanges on the expressways.
That could take several months, he said.
Moose said it's unlikely there would be any new money for the shoulder project. He doesn't know how much it would cost, in part because it's not clear whether the DOT would attempt any significant bridge work. It could cost between $5 million and $10 million if bridge work is needed.
He would have to ask the Mecklenburg-Union Metropolitan Planning Organization to postpone other projects.
"But I would argue that the bang for your buck would be great," Moose said. "An extra lane would be a great return on investment."
Shoulder lanes for rush hour