Interstate 526 South Carolina

Westbound Interstate 526 (Mark Clark Expressway) crosses the Cooper River over the Don N. Holt Bridge. An integral connection through into North Charleston, the steel through truss bridge with an 800 foot long main span opened on March 10, 1992 and cost $20 million to build.¹ 05/30/07

Overview

Connecting with U.S. 17 on both sides, Interstate 526 constitutes a belt route to the north of Charleston through the city of North Charleston. The freeway crosses over the Cooper River on the Don N. Holt Bridge, a three span continuous modified Warren truss (structural steel).¹ A second high level span, the James B. Edwards Bridge, takes I-526 across the Wando River between Daniel Island and Mount Pleasant.

The eastern end of Interstate 526 connects with both U.S. 17 at Hungry Neck Road and Business Spur I-526 (Coleman Boulevard) west toward Sullivan’s Island. The west end connects with U.S. 17 at S.C. 7 (Sam Rittenberg Boulevard) in west Charleston. Roadway stubs and grading there were built for the eventual southeasterly extension of the freeway toward Folly Beach and onto James Island. The James Island Expressway, S.C. 30 between S.C. 171 (Folly Road) and Downtown Charleston, represents the future southern extent of I-526.

Debated and delayed for two decades, the South Carolina Department of Transportation (SCDOT) moved forward on a contract to complete the remaining portion of I-526 on December 5, 2013. This measure advanced after the Charleston County Council voted to proceed with the contract in December 2013. The initial contract was estimated at $558 million.³ Despite the optimism for a possible 2020 completion of I-526,⁴ funding was not finalized and work on I-526 has remained on hold.

Route Information

East End – Mt. Pleasant, SC
West End – Charleston, SC
Mileage – 19.26
Cities – Charleston, North Charleston
Junctions –

Source: December 31, 2021 Interstate Route Log and Finders List

I-526 Average Annual Daily Traffic (AADT)

Source: 2018 AADT – SCDOT Traffic Counts 2009-2018

History

The American Association of State Highway and Transportation Officials (AASHTO) approved the numbering of Interstate 526 initially on June 29, 1978 from I-26 southeast to U.S. 17/701 in Mount Pleasant. The first section of I-526, the Mark Clark Expressway between U.S. 17 and S.C. 642 (Dorchester Road), was designated as S.C. 31. The freeway through west Charleston was named in 1976 after General Mark Clark, a World War II hero and former president of The Citadel, Charleston’s military college.⁵

The western extension of I-526, from North Charleston to S.C. 7 was approved by AASHTO on October 6, 1989. The route was signed shortly thereafter, starting with the section that was previously signed as S.C. 31 from U.S. 17 northeast to I-26. Dedicated on June 20, 1992,² Interstate 526 was extended southeast to rejoin U.S. 17 north of Charleston with the completion of the Don N. Holt Bridge over the Cooper River. The freeway directly transitions onto Business Spur I-526 in Mt. Pleasant, which was also signed in 1992.

S.C. 31 was reused with the December 17, 2002 opening of the Carolina Bays Parkway between U.S. 501 and S.C. 9 to the north of the Grand Strand. Included in the future I-74 corridor from southeastern North Carolina, Carolina Bays Parkway was extended west to S.C. 544 on December 15, 2004.

The east end of I-526 was improved with a new single point interchange connecting the freeway with U.S. 17 at Hungryneck Boulevard in Mount Pleasant. Costing $26.7 million, the exchange was completed in January 2013.⁶ Associated work reconfigured the original parclo interchange joining I-526 and Business Spur I-526 (Chuck Dawley Boulevard) with U.S. 17 to the west to eliminate signalized turns. Motorists are instead directed to the new ramps at Hungryneck Boulevard to the east, or the grade separated intersection further west along U.S. 17 at Bowman Road.

Photo Guides

Interstate 526 South Carolina

East End – Mount Pleasant, South Carolina

East at

Interstate 526 angles southward toward the wye interchange (Exit 29) with the connector to U.S. 17 at Hungryneck Boulevard. 12/31/17

Exit 29 separates from I-526 eastbound. Widening along U.S. 17 finished in January 2013 included the addition of a single point urban interchange (SPUI) with the freeway connection from Exit 29 at Hungryneck Boulevard. 12/31/17

The remainder of I-526 leads south to a parclo interchange (Exit 30) with U.S. 17 south and Business Spur I-526 (Chuck Dawley Boulevard). 12/31/17

South at

U.S. 17 heads southwest from Mount Pleasant Towne Center to the single point interchange with Hungryneck Boulevard and the access ramps to Interstate 526. 12/31/17

Ramps joining Hungryneck Boulevard and U.S. 17 with I-526 west join the freeway mainline ahead of Long Point Road and the James B. Edwards Bridge across the Wando River. 12/31/17

North at

Six lane expansion of U.S. 17 (Johnnie Dodds Boulevard) through Mount Pleasant added a diamond interchange with Bowman Road just to the west of I-526 and Business Spur I-526. The ramp for Chuck Dawley Boulevard south was relocated to depart from the entrance ramp at Bowman Road. 12/31/17

A loop ramp follows from U.S. 17 (Johnnie Dodds Boulevard) north onto I-526, which extends north from Business Spur I-526 toward Daniels Island and North Charleston. 12/31/17

The SPUI with Hungy Neck Boulevard provides a second entry point for I-526 west from U.S. 17 northbound at Mt. Pleasant. 12/31/17

West at

Westbound Business Spur I-526 transitions onto Interstate 526 just north of Bowman Road. With the interchange built at U.S. 17 and Bowman Road in 2012, Exit 30 was modified to connect with U.S. 17 northbound only. 12/31/17

East End Throwback

U.S. 17 north at the former off-ramp for Business Spur I-526 eastbound. Chuck Dawley Boulevard loops southwest to S.C. 703 (Coleman Boulevard) through Mount Pleasant. 01/18/04

Replaced button copy signs on U.S. 17 north for I-526 west to North Charleston. 01/18/04

Replaced button copy gore point sign on U.S. 17 north at I-526 west. Photo by Chris Patriarca (06/12/03).

Prior to completion of the SPUI here in 2013, the connector linking U.S. 17 south with I-526 west at Hungry Neck Boulevard originated at an at-grade intersection. Photo by Chris Patriarca (06/09/03).

Original guide signs for U.S. 17 south at Business Spur I-526 (Chuck Dawley Boulevard). Photo by Chris Patriarca (06/09/03).

Former button copy overheads at the exchange joining I-526 with U.S. 17 at Mount Pleasant. Photo by Chris Patriarca (06/09/03).

Exit numbers along I-526 between Mount Pleasant and Daniel Island (Exit 24) were unnumbered originally. 01/18/04

West End – western Charleston, South Carolina

West at

End freeway signs precede the ramps for S.C. 7 (Sam Rittenberg Road) and U.S. 17 (Savannah Highway) along Interstate 526 in west Charleston. 12/31/17

All traffic on I-526 shifts onto the ramp for S.C. 7 and U.S. 17. A roadway stub and grading allude to the planned extension south to James Island. 05/30/07

Succeeding traffic lights connect the western end of I-526 with S.C. 7 (Sam Rittenberg Boulevard) and U.S. 17 (Savannah Highway). S.C. 7 provides a cut off for U.S. 17 south toward Savannah while the arterial route northbound leads to adjacent Citadel Mall and the city of North Charleston. 12/31/17

An overpass carries traffic from U.S. 17 northbound to I-526 east above the signalized intersection connecting I-526 west with Savannah Highway. U.S. 17 heads 3.5 miles east to S.C. 171 for Folly Beach and 4.6 miles to Downtown Charleston. 05/30/07

North at

A loop ramp for I-526 eastbound follows the signalized intersection joining U.S. 17 with S.C. 7 (Sam Rittenberg Boulevard). I-526 and S.C. 7 both lead northeast across the Ashley River to North Charleston. 05/30/07

A loop ramp follows the signalized intersection with S.C. 7 (Sam Rittenberg Boulevard) for I-526 eastbound. I-526 and S.C. 7 both lead northeast across the Ashley River to North Charleston. 12/27/06

The flyover leading Interstate 526 north across both U.S. 17 (Savannah Highway) and S.C. 7 (Sam Rittenberg Boulevard) was completed in 1999. 12/27/06

South at

An array of businesses line both sides of U.S. 17 (Savannah Highway) within the vicinity of the partial interchange with Interstate 526 (Mark Clark Expressway). 11/12/06

I-526 heads seven miles north to the exchange with Interstate 26 in North Charleston. The four lane section of U.S. 17 extends west another 25 miles to Jacksonboro 11/12/06

Overhead signs were added at the on-ramps for I-526 in both directions of U.S. 17 (Savannah Highway) between 2003 and 2006. 11/12/06

Throwback – West at

An original button copy guide sign for the west end of Interstate 526. 01/18/04

Future West End – at Lockwood Drive – Charleston, South Carolina

East at Lockwood Drive

Interstate 526 will overtake S.C. 30 along the James Island Expressway eventually. The freeway spans the Ashley River into Downtown Charleston beyond the trumpet interchange (Exit 1) with S.C. 61 (Herbert U. Fielding Connector). Photo by Chris Patriarca (06/12/03).

Crossing the Ashley River, S.C. 30 approaches a six-ramp parclo interchange with Lockwood Drive. Photo by Chris Patriarca (06/12/03).

The James Island Expressway concludes at this partition for ramps to Calhoun Street east into Downtown, Lockwood Drive south to the historic Battery district, and the continuation of S.C. 30 north. Photo by Chris Patriarca (06/12/03).

Calhoun Street stems east from the James Island Expressway directly while S.C. 30 turns north along Lockwood Drive to connect with U.S. 17 at Spring and Cannon Streets. Photo by Chris Patriarca (06/08/03).

Lockwood Drive North at

Lockwood Drive straddles the west shore of the Ashley River from the historic Battery to become a part of S.C. 30 at the James Island Expressway outside Downtown. 08/18/19

A loop ramp departs from Lockwood Drive for S.C. 30 west across the Ashley River to James Island and S.C. 171 to Folly Beach. Photo by Chris Patriarca (06/12/03).

Lockwood Drive South at

S.C. 30 follows Lockwood Drive a quarter mile south from U.S. 17 (Spring / Cannon Streets) to the James Island Expressway (future I-526) across the Ashley River. Photo by Chris Patriarca (06/12/03).

Calhoun Street West at

Westbound Calhoun Street transitions onto the James Island Expressway (S.C. 30) at the exchange with Lockwood Drive. Photo by Chris Patriarca (06/12/03).

Sources:

Case Studies: Cooper River Bridge Fact Sheet. ~~http://www.cee.cornell.edu/academic/case_studies/cooper/index.cfm~~ Cornell University.
“Spartanburg officials joyous over decision.” Herald-Journal (Spartanburg, SC), June 21, 1992.
“SCDOT Commission approves revised I-526 contract.” The Post and Courier (Charleston, SC), December 5, 2013.
“SCDOT Commission approves I-526 completion project.” WCBD-TV2 (Charleston, SC), December 5, 2013.
“State’s Praises Often Hit the Road S.C. has Traditiion of Naming Roads.” The State (Columbia, SC), February 12, 1996.
“Just Like Legos U.S. 17 in Mt. P. to close 5 nights for I-526 overpass installation. The Post and Courier (Charleston, SC), May 14, 2012.

Page updated September 27, 2021.