Will wider I-485 bring only partial relief?

03/18/2014 7:06 PM

03/18/2014 10:40 PM

The completion later this year of a long-awaited Interstate 485 widening project will shorten the afternoon commute for thousands of drivers, who today face stop-and-go traffic.

But expanding the oldest section of the southern outerbelt could make the morning commute worse.

There are two areas of concern:

• That the improved outerbelt will encourage more people to use the interstates for commuting, which will put more cars on an already full Interstate 77.
• Additionally, the faster outerbelt will allow cars to reach I-77 more quickly, possibly making congestion on that north-south highway more severe.

The effect could be like putting more water through a small funnel.

“We do understand there will be a larger queue (of inbound cars) that gets to 77 quicker,” said Louis Mitchell, the N.C. Department of Transportation engineer who supervises the project in Charlotte.

He added: “We want to prioritize the widening of I-77. But we have to take small bites at the apple.”

The conundrum highlights the Transportation Department’s race to meet the fast-growing region’s transportation needs. And it will give new urgency for the state to find a long-term solution to widening I-77 from uptown to the South Carolina state line – a complicated project that is expected to cost at least $1 billion.

Explosive growth

First the good news:

When Interstate 485 was first built in the late 1980s, the state didn’t foresee the explosive growth that would occur in Ballantyne and western Union County – development that was sparked by the highway itself.

According to the state’s most recent traffic count, I-485 at the Pineville-Matthews Road exit carries 112,000 vehicles a day. That was on a total of four lanes, meaning each lane was loaded with about 27,000 vehicles.

By comparison, I-85 at North Graham Street – which has eight lanes – handles 164,000 vehicles a day. That’s 20,500 vehicles per lane.

N.C. DOT’s $82 million contract with Lane Construction will build a third lane each way on I-485 from I-77 to Rea Road. The project also includes a flyover access bridge for drivers on Johnston Road north who are seeking to merge onto the inner loop of I-485.

The completion date for the project is December.

Despite the rainy weather, much of the construction work on the new lanes is complete, except for the construction of bridges over roads and creeks.

Mitchell said some parts of the project will likely open before December. The Johnston Road flyover is scheduled to open in July.

“We’ll start to remove the barriers in phases,” Mitchell said.

He also said the highway will open with just one extra lane in each direction. But the current project has room for a fourth lane each way. The state would just have to repaint the highway.

Lane Construction referred calls about the project to N.C. DOT.

The Transportation Department hasn’t projected just how many new vehicles will use the outerbelt after the extra lane opens. The improved outerbelt could also encourage more people to live farther from the city, lured by the promise of a faster commute.

“We think the Ballantyne area and Union County will see growth as well,” Mitchell said. “Certainly we hope the highway will operate on an acceptable level.”

The Transportation Department also hasn’t forecast how the outerbelt expansion will impact I-77. If more people are using the outerbelt in the morning, that will mean more vehicles merging on I-77, possibly creating more severe traffic jams.

$100 million per mile

I-77 just south of uptown is one of the state’s busiest highways, carrying more than 160,000 vehicles. Widening the highway will be expensive – more than $100 million per mile – because there is little room to expand.

Houses and businesses sit along the highway. There are embankments near the shoulder, which means there is no easy place to add a lane.

“We are bounded by development already,” Mitchell said. “That makes the right-of-way costs just as high as the road construction costs.”

The state plans to open proposals from contractors at the end of March for a $600 million widening of I-77 in north Mecklenburg.

N.C. DOT is planning to enter into a public-private partnership to add a toll lane to the interstate. The toll lane, also called a HOT lane, would require drivers to pay a fee, which would guarantee them a certain speed. The more people who want to use the lane, the higher the toll.

It’s possible when I-77 south of uptown is expanded this decade or next, it could include a HOT lane.

“I’m sure that will be a part of the discussion,” Mitchell said.

The I-485 widening is one of several large highway projects underway.

The state expects the widening of Interstate 85 in Cabarrus County to be finished in two phases, in May and July. In addition, the northeast section of I-485 is scheduled to be finished in December.

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