36 • JUNE 2008 • ROADS & BRIDGES WWW.ROADSBRIDGES.COM

After three decades, I-65/Corridor X Interchange fi nally reaching completion

Some 30 years after the Appalachian Regional Commission approved the designation of

Corridor X from Fulton, Miss., to Birmingham, Ala., the project is fi nally nearing comple-

tion. There are good reasons why it has taken this long to complete the fi nal segment

connecting Corridor X to I-65 in Birmingham. The challenges were enormous: The in-

terchange is geometrically complex, the environmental context is sensitive, I-65 currently carries

85,000 vehicles per day through the project area and several major utility lines run right through the

interchange area.

BY PHIL LOHR, P.E., PTOE,

AND

WM. CAREY KELLY, P.E.

CONTRIBUTING AUTHORS

To complete this massive undertak-ing, the Alabama Department of Transportation (ALDOT) enlisted the services of Volkert and Associ-ates Inc., headquartered in Mobile, Ala., and with offi ces throughout the southeast. The Corridor X portion of the interchange area begins 1.4 miles northwest of I-65 and extends 2,000 ft southeast of I-65 to U.S. 31. The I-65 portion begins at 16th Street, just north of I-59/I-20, and extends 5.4 miles north to Walkers Chapel Road. Faced with an estimated construc-tion cost approaching $300 million, ALDOT and Volkert realized that it would be cost-prohibitive to design and construct the project as a single entity. Thus they divided the project into six plan sets.

Sensitive angleThe fi rst challenge of the I-65/Cor-

ridor X interchange area is the shear geometric complexity. The main in-terchange will be four levels and fully directional. To accommodate the projected traffi c, the interchange requires collector-distributor roads paralleling I-65 northbound and southbound. Just northwest of the in-terchange, Corridor X is shoehorned

in between an established residential neighborhood and a Norfolk South-ern railroad line. The neighborhood streets are as much as 100 ft higher than Corridor X, while Corridor X is as much as 60 ft higher than the nat-ural drainage channels located in the valleys between these same streets. After passing under I-65, Corridor X climbs rapidly to pass over Lewis-burg Road and tie in to U.S. 31.

The second challenge of the I-65/Corridor X interchange area is the sensitive environmental con-text. The New Georgia Landfi ll (an active city-of-Birmingham facility) is located in the northern quadrant of the interchange while the T.M. Burgin Landfi ll (a closed construc-tion-debris facility) is located in the eastern quadrant of the interchange. Furthermore, an abandoned fi ring range is located in the vicinity of the I-65 southbound to Corridor X west-bound ramp. In order to minimize the risk of disturbing lead or other potential contaminants, ALDOT and Volkert agreed early in the design process that there would be no exca-vation in the northern quadrant—all roadways and ditches would be con-structed entirely with fi ll.

The T.M. Burgin Landfi ll in the eastern quadrant posed a different challenge. While the goal in design was to minimize disturbance of this landfi ll, the area could not be com-pletely avoided, since a major drain-age system fl owing northwest from U.S. 31 toward I-65 is routed under the middle of this landfi ll. The out-let of this system, located just east of existing I-65, is a 1/4 -in.-thick, 5-ft by 5-ft steel-box culvert with diagonal bracing conveniently placed inside to catch trash and reduce fl ow ca-pacity. Excavating and replacing this system was not an option—ALDOT had no desire to acquire and disturb a closed landfi ll.

Volkert was understandably re-luctant to connect to this system at the upstream end west of Lewisburg Road. The solution? Most of the fl ow entering this system is diverted into a new system running northwest along Corridor X from the U.S. 31 interchange area to the west side of I-65.

Two major creeks passing under I-65 also were areas of environmental concern. Village Creek passes under I-65 south of the Corridor X inter-change, while Five Mile Creek fl ows

The challenges of the I-65/Corridor X projects were enormous. The interchange is geometrically com-plex, the environmental context is sensitive, I-65 currently carries 85,000 vehicles a day and several major utility lines run right through the interchange area.

38 • JUNE 2008 • ROADS & BRIDGES WWW.ROADSBRIDGES.COM

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east to west under I-65 north of Cor-ridor X. One of the biggest concerns at Five Mile Creek is an in-place 10-ft by 6-ft box culvert that empties into a 460-ft-long concrete channel that subsequently empties into Five Mile Creek on the east side of I-65. This culvert collects storm-water runoff from under almost a mile of I-65 and has a design fl ow of approximately 700 cu ft per second (cfs). Because of right-of-way constraints, deten-tion is diffi cult, but Volkert designed two ponds within the infi eld areas of the I-65/U.S. 31 interchange. This reduces the design fl ow in the cul-vert by over 100 cfs. Being concrete and steep, the in-place outfall chan-nel fl ows fast, and scour is evident where the channel empties into Five Mile Creek. To alleviate this area, Volkert designed a riprap energy ba-sin and outfall channel to replace the existing concrete channel.

The list of environmental concerns is rather extensive. Joe Money Ma-chinery is located in the southern

quadrant of the I-65/Corridor X in-terchange. Two of the interchange bridges are located right over and are designed with bents in Joe Money’s distilling ponds, where water from washing heavy equip-ment was formerly collected. Some contamination was found in the northern end of the two ponds, and ALDOT has already acquired and fi lled that pond under a different contract. No contamination was found in the southern pond, and it is to be drained and fi lled as part of this project.

The entire project area along I-65 was historically important for coal mining and industry. The mines are closed, but even today the entrance to one is still visible within the in-terchange area. Based on the mine studies conducted for this project, it can be expected that more his-torical evidence of mining could be encountered during construction. One fi nal item of environmental interest was the discovery of small

ROADS & BRIDGES • JUNE 2008 • 39

The design goal for the traffic-control plan was to keep all ramps and six lanes on I-65 open at all times. During devel-opment of the traf-fic-control plans, it became apparent that some ramps would have to be closed temporarily and de-tours provided.

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traces of trichloroethylene in the vicinity of the ramp gore from the northbound CD road to westbound on Corridor X. The source could not be identifi ed, so once again Volkert raised the elevation of some drainage structures and designed a ditch in fi ll in order to avoid disturbance in this area.

Heavy sheet traffi cThe third challenge of the I-65/

Corridor X interchange area is main-tenance of traffi c, primarily vehicu-lar on I-65 and its ramps but also rail traffi c on the six active lines passing under I-65. The design goal for the traffi c-control plan was to keep all ramps and six lanes on I-65 open at all times. During development of the traffi c-control plans, it became ap-parent that some ramps would have to be closed temporarily and detours provided. But the goal of keeping six lanes open on I-65 was attained, aside from brief temporary closures for set-ting bridge girders and for blasting. For Plan Set 2, covering the heart of

the interchange, over 150 plan sheets representing approximately 10% of the entire plan assembly are devoted to the traffi c-control plan.

Lines start hereThe fourth challenge of the I-65/

Corridor X interchange area is the presence of several major utility lines, most notably those of the Alabama Gas Corp. (AGC), Southern Natural Gas Co. (SNGC) and the Alabama Power Co. (APC). AGC has 4-in. and 12-in. high-pressure lines running adjacent to the Norfolk Southern railroad line on the west side of I-65 through the Corridor X interchange. SNGC has a 24-in. high-pressure gas line crossing Corridor X about one mile west of I-65, passing north of the New Georgia Landfi ll and cross-ing under I-65 at Five Mile Creek.

SNGC had 20- and 22-in. high-pres-sure gas lines passing right through the I-65/Corridor X interchange. Af-ter extensive deliberations and nego-tiations, ALDOT and SNGC agreed that the best course of action would

be to relocate the 20- and 22-in. lines within the same easement as the 24-in. line. This project has now been completed, clearing the way for con-struction of the interchange. APC had power lines that crisscrossed the Corridor X alignment throughout this project. Like the gas lines, this has required a major relocation effort.

Construction is already under way on Plan Set 1. The R.R. Daw-son Bridge Co. was awarded the construction contract in September 2007. New bents on the west side of I-65 for widening the bridge over Daniel Payne Drive and the newly graded northbound off-ramp from I-65 to Daniel Payne Drive need to be completed early for coordination with the construction efforts on Plan Set 2, which is scheduled for letting later this year.

Extensive erosion-control netting to protect the cut slope until vegeta-tion is established also will be used, as well as the use of riprap on the widening of the I-65 bridge over Vil-lage Creek to protect the creek banks during construction. ALDOT intends to use similar erosion- and sediment-control measures during construc-tion in the vicinity of Five Mile Creek on Plan Set 2.

Most of the other plan sets also are nearing completion. Plan Set 3 is scheduled for letting soon. Plan Set 4 is scheduled for letting in 2009. De-sign of Plan Set 6 is approximately 70% complete, with letting sched-uled for 2010. West of Fulton, Miss., U.S. 78 is already a controlled-ac-cess facility to the Tennessee state line southeast of Memphis, Tenn. It is expected that eventually this con-trolled-access facility will be con-nected to one of the interstates near Memphis, thus completing the I-22 link all the way from Memphis to Birmingham.

Lohr is a project manager with Volkert & Associates Inc., Chat-tanooga, Tenn. Kelly is with the Alabama DOT.

LearnMore!For more information related to this article, go to: www.roadsbridges.com/lm.cfm/rb060814

40 • JUNE 2008 • ROADS & BRIDGES WWW.ROADSBRIDGES.COM

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