On Wednesday, a leading truck research organization named the Atlanta interchange known as "Spaghetti Junction" the country's most congested truck thoroughfare for the second straight year. There's a reason for the dubious distinction: When it comes to tendering spot, or non-contractual, freight, Atlanta is a happening place.

For the second straight year, Atlanta, a national hub with strong road and rail connections, topped the list of markets in 2016 with the most available van and refrigerated loads for outbound spot market transport, according to data released today by DAT Solutions, one of the leading providers of load board information where shippers and brokers post loads to be hauled. Little Rock, Ark., was the leader in flatbed loads, taking the top spot for the second straight year.

For dry vans, the nation's most common form of trailer equipment, Houston finished second, also for the second straight year. It was followed by Chicago; Dallas; and Charlotte, N.C. Chicago leaped from eighth place, while Los Angeles jumped to seventh from 16th. Cleveland fell from third to eighth.

In reefers, Chicago was second, rising from sixth. It was followed by Elizabeth, N.J.; Dallas; and Twin Falls, Idaho, with the latter climbing from ninth. Twin Falls is a large potato and onion producing area, which explains its prominence in the spot reefer market. Los Angeles jumped to seventh from 23rd, while Joliet, Ill., 40 miles southwest of Chicago, rose to ninth from 24th.

In flatbeds, Shreveport, La., was second, followed by Mobile, Ala.; Jackson, Miss.; and Cleveland. Spokane, Wash., jumped to 10th from 44th, according to DAT data. Company executives were immediately unavailable to comment on the report.

The list of highway bottlenecks is compiled by the American Transportation Research Institute (ATRI), a nonprofit organization that is part of the trade group American Trucking Associations (ATA). ATRI assesses truck congestion levels at 250 locations on the 161,000-mile National Highway System. The analysis is based on GPS data culled from the operations of more than 600,000 heavy-duty trucks.

ATRI estimated that congestion on the National Highway System, which includes the 44,000-mile Interstate Highway System, cost the trucking industry $49.6 billion in 2014, the last year that firm numbers were available. Congestion resulted in 728 million hours of lost commercial driver productivity, equal to 264,500 drivers sitting idle for one year, ATRI said.

About 18 percent of the national system accounts for 88 percent of the congestion, ATRI said. It said that efforts to reduce or eliminate the major bottlenecks could go a long way toward solving the overall congestion problem.