3-D visual simulations of the 30 Crossing project show the Arkansas Highway and Transportation Department’s six-lane option creates much smoother traffic flow than an eight-lane alternative.
The department displayed the options during a public meeting Tuesday at the Wyndham Hotel in North Little Rock. The simulations can be seen at this link.
The 30 Crossing is a $630.7 million project that is widening, reconstructing and rehabilitating parts of Interstate 30 and Interstate 40 through North Little Rock and Little Rock. The project will include widening the Arkansas River bridge. Sixty-four percent of the project is funded by the Connecting Arkansas Program, which comes from a 10-year half-cent sales tax passed by voters in 2012.
At the public meeting, attendees were shown two alternatives: the Highway Department-favored six-lane alternative with two connector-distributor lanes in each direction, and an eight-lane alternative with four lanes in each direction.
The six-lane alternative has been refined after some questioned the original design. Previously, it has been referred to as a 10-lane system. AHTD Director Scott Bennett said in an interview prior to the presentation that 10 lanes incorrectly implies a system “where everybody’s just going to be blowing and going through town.”
3-D simulations were created by Garver, the project manager for the 30 Crossing project, and Kansas City-based HNTB. The two simulations show the same number of cars moving through both alternatives. The eight-lane system shows significant congestion; the six-lane with four connector-distributor lanes has almost no congestion, the result of fewer and more coordinated entry and exit points. The connector-distributor model was used for the recently completed Big Rock Interchange at I-630 and I-430.
“With the eight lanes, there are still going to be a lot of choke points that lead to a lot of congestion in the future, and that’s what the modeling shows,” Bennett said.
In addition to those alternatives, project designers are considering two types of interchanges – a single point urban interchange at Highway 10, where a current interchange exists, and a split diamond model with interchanges on both sides, which would combine access at 4th, 5th, 6th and 9th streets. The single point interchange is controlled by a single set of traffic signals under the interstate from which all turning movements occur. With the split diamond, traffic coming south over the bridge would exit at Fourth Street instead of 2nd Street at the River Market, as it currently does. Traffic traveling northbound would enter the interstate at 6th and 9th Streets.
The two interchange models each have their strengths, said Garver’s Jerry Holder. The split diamond is cheaper, disperses traffic into the downtown grid better, and has a smaller footprint. The single point model moves traffic more efficiently.
Bennett said 82% of the corridor’s traffic originates in or is destined for points along the corridor, while 18% is through traffic.
Opponents of the project have pushed for a boulevard model, saying that these current models will attract traffic and induce congestion. Bennett said that a boulevard model won’t work because of engineering and traffic flow challenges.
Planners will take comments based on this public meeting through June 10 and then will present hopefully one alternative in the fall, Bennett said.