Every year, the South Carolina economy loses millions of dollars because of delays caused by traffic congestion, and the problem is expected to grow with the population, which is estimated to rise by 30 percent in the next three decades, according to highway planners.

$4 billion statewide for road upgrades

Includes widening four miles of Interstate 526

Re-designing Interstates 26 and 526 interchange

Better interstate signs and re-striped lanes

Efforts to promote carpooling, telecommuting and staggered work times

Key to addressing the situation are planned interstate upgrades that are laid-out in a draft copy of the Statewide Transportation Improvement Program.

On Thursday, the state Department of Transportation Commission considers approval of a new STIP that describes how $4 billion in state and federal funds will be spent on roads during the next six years.

About $150 million for Interstate-526 improvements is included in the new STIP. Some $8 million is designated for federal fiscal year 2018 for engineering design and environmental analysis for four miles of the interstate between Paul Cantrell and International boulevards. The lion’s share of the funds, $120 million, goes to creating a better interchange for Interstates 526 and 26, which drivers have long complained is a traffic chokepoint.

Next month, more funds could become available for the estimated $553 million I-526 project when the State Transportation Infrastructure Bank board votes on which interstates will benefit from a General Assembly appropriation of $50 million annually for 10 years. The bank will use the funds to finance $500 million for road work, officials said.

If I-526 gets a big chunk of the new funds, the schedule to widen the highway and improve the I-526/I-26 interchange will be accelerated, said Mark Lester, DOT director of planning.

The state-maintained highway system is the fourth largest in the country. South Carolina oversees interstate, state, U.S. and secondary routes totaling about 41,000 miles. It maintains 8,387 bridges, about 20 percent of which are considered substandard but not unsafe.

South Carolina needs to make more than $28 billion worth of repairs just to get its roads to “good” condition, state DOT Secretary Robert St. Onge said recently.

The state has one of the highest death rates per miles traveled. It relies on the highway system to move the majority of its freight, and there are emerging air quality concerns that reflect more stringent federal standards.

“It becomes clear that the funding objectives and projects identified in the STIP are critical to providing mobility and accessibility for people, goods and services,” the document states.

The STIP only includes projects for which there is committed funding available. It is the state’s six-year transportation improvement plan for road work receiving federal funding, including bridge replacement, highway resurfacing and interstate maintenance.

Other efforts to relieve I-526 congestion included in the STIP are $150,000 for an effort to encourage carpooling. Another $150,000 is aimed at traffic-busting measures such as staggered work times.

A DOT engineer last week described a widening plan for I-526 to a joint meeting of the bank board and the DOT Commission. The plan would accelerate widening work on the highway depending on whether the SIB approves new funding. The first phase of construction would start in 2019.

The DOT Commission recently approved a list of interstate upgrades recommended by its staff. That list will be considered by the bank board in September. It also must be approved by the General Assembly Joint Bond Review Committee.

Some have expressed concern that the bank board will not follow the DOT list of priority interstate projects. SIB Chairman Don Leonard said at the meeting that the bank and the DOT see eye-to-eye on which road work is a priority.