Meetings to begin over I-30 corridor

Plans to widen based on 2003 study

Traffic slows (left) on I-30 eastbound near W. 9th St. in Little Rock in this 2014 file photo.
Traffic slows (left) on I-30 eastbound near W. 9th St. in Little Rock in this 2014 file photo.

Widening the Interstate 30 corridor to 10 lanes through Little Rock and North Little Rock was the only option considered that would provide an "acceptable" level of service on the three downtown Arkansas River crossings, according to an 11-year-old study that the Arkansas Highway and Transportation Department is using to guide plans to renovate the highway.

Level of service is a universal way for highway engineers to describe conditions in traffic. Key measures include speed and travel time, the density of traffic and delays. There are six levels of service, ranging from A, which is "free flow, accompanied by low volumes and high speeds," to F, which is "forced-flow operation at low speeds, where volumes are below capacity."

Service levels A, B and C are considered acceptable, especially for corridors in urban areas. But the Areawide Freeway Study, released in 2003, found that, at peak volumes, several parts of the I-30 corridor were at service levels E and F, with E levels seeing speeds typically in the range of 30 mph with volumes at or close to corridor capacity.

"Traffic volumes approach, and at times exceed, the capacity of the road," the study concluded.

At the same time, though, the price to widen the corridor, including the I-30 bridge over the river -- estimated then at $116 million -- represented the second-highest cost of the alternatives considered and the alternative with the lowest benefit-to-cost ratio, according to the study by The Louis Berger Group Inc.

The 2003 study will serve as a "building block" for the study the Highway Department is doing now, said Randy Ort, an agency spokesman. "We think it is a good document, but things have changed. It served its purpose."

The cost of improving the corridor today is estimated to be in the range of $450 million, which would include replacing the bridge over the Arkansas River.

The alternative identified in the study concluded the best benefit-to-cost ratio was building a fourth downtown river crossing, which also was found to be the most expensive option considered. But that fourth downtown river crossing no longer is an option as engineers once again study ways to improve the 6.7-mile I-30 corridor that runs from Interstate 530 south of the river to U.S. 67/167 north of the river and includes a section of Interstate 40 connecting I-30 to U.S. 67/167.

The bridge alternative would have gone through where Dillard's Department Stores headquarters and Episcopal Collegiate high school now sit along Cantrell Road. Another site for a bridge, at Chester Street, is not on Little Rock's master street plan.

"We have to deal with the reality today," said Jerry Holder, an engineer with Garver LLC, an engineering, planning and environmental services firm based in North Little Rock. Holder is the I-30 corridor project construction manager.

The 2003 study is being used as a "starting point" as state highway officials prepare to hold the first two public meetings this week to solicit ideas on how they should improve the corridor and deal with issues involving businesses, neighborhoods, churches, schools, wetlands and other constraints that engineers should keep in mind when considering adding lanes and heavily modifying or replacing the bridge carrying I-30 across the Arkansas River, Holder said.

"We used it as a starting point to inform ourselves," he said. "But it's 11 years old. A lot of things have changed in 11 years."

Holder and other engineers also will be using this week's meetings to learn about the area through which the corridor travels.

"We will be in listening mode," he said. "We want people to come in and tell us where the problems are."

The first meeting will be held Tuesday in the Bank of the Ozarks conference center at the North Little Rock Chamber of Commerce, 100 Main St. in North Little Rock. The second will be Thursday in the Cash/Campbell ballroom at the Comfort Inn & Suites Presidential, 707 I-30 in Little Rock. Both meetings will last from 4 to 7 p.m.

The meetings will be held in an open-house format to allow the public to view maps and exhibits, to ask questions and to provide input on the study. The project is part of the department's $1.8 billion highway construction program.

The problems associated with the corridor go beyond it being "generally limited" to six lanes, the 2003 study said. Some of its problems are related to the highway's design, which is more than 50 years old and not up to modern standards.

"These include many on and off ramps in a short distance, high weaving and merging volumes, and lack of proper shoulders on the I-30 Bridge," the study said. "In the southbound direction of I-30, there are ten ramp junction points in a 2.5-mile section of road; in the northbound direction, there are nine.

"Under ideal conditions, interchanges should be two miles apart in an urban area. The multiple ramp junctions and the close spacing between them create merging, weaving and diverging movements that have an adverse impact on the capacity and safety of the freeway. In addition, many of the ramps are short, providing limited deceleration/acceleration distances and short storage lengths."

Even without those design flaws, demand exceeds capacity, particularly on the bridge.

Under ideal conditions, a freeway lane can carry 2,400 passenger cars per hour, the study said. But "the lack of shoulders on the I-30 bridge and the close proximity of major merge and diverge areas will lower the free flow speed by 10 mph and reduce the capacity to 2,250 passenger cars/lane/hour. In addition, the freeway lane capacities are reduced an additional 100 passenger cars/lane/hour due to friction at the merge and diverge points near the bridge approaches."

The design problems cost the corridor another 10 percent to 15 percent of capacity, the study found. And once the corridor becomes congested, capacity drops another 10 percent to 20 percent, operating at 1,800 to 1,900 passenger cars per lane per hour.

The study said the loss of capacity "creates significant queues on I-30 that interfere with the on-ramp merge conditions," as any motorist who regularly travels the corridor can attest.

Metro on 08/11/2014

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