Interstate 10 travels 66.30 miles across Mobile and Baldwin Counties as part of its route across the upper Gulf Coast between Biloxi/Gulfport, Mississippi and Pensacola. The freeway enters Alabama near Grand Bay, traveling east as a rural four-lane freeway through to Theodore and southwestern reaches of Mobile.
A six-ramp parclo interchange opened to traffic along Interstate 10 at McDonald Road on January 12, 2005. Numbered Exit 10, the exchange links I-10 with County Road 39 north to west Mobile and south to U.S. 90 at Irvington, and Half Mile Road to Bayou La Batre. The new four-lane highway for CR 39 was completed in June 2009.
Widening of I-10 to six lanes was completed from Carol Plantation Road east to SR 193 (Exit 17) by fall 2014. Continuing east from Tillmans Corner, commuter traffic adds to I-10 through to the south end of Interstate 65. The urban freeway maintains six overall lanes, with auxiliary lanes accompanying both directions of the route through Mobile.
Back to back lane drops occur along Interstate 10 eastbound at the Canal Street off-ramp and Water Street interchange south of Downtown, as the freeway lowers into the George Wallace Tunnel below the Mobile River. Regular congestion occurs at the tunnel due to the steep descent and merging traffic from the Water Street on-ramp. An interim measure was implemented on June 24, 2017, when the Water Street on-ramp was closed to traffic.
Emerging from the four-lane Wallace Tunnel, Interstate 10 ascends onto the Mobile Bayway. Also known as Jubilee Parkway, the Bayway spans the shallow waters of Mobile Bay along a viaduct system extending eight miles east to Spanish Fort and the Baldwin County Eastern Shore. U.S. 90 & 98 parallel the four-lane freeway along Battleship Parkway, a causeway just a few feet above sea level, nearby.
Variable speed limits are used throughout the Mobile Bayway. Changeable speed limits coincide with a fog detection system implemented along the viaduct following the events of March 20, 1995. Dense fog that day resulted in a 100 plus vehicle pile up, killing one and seriously injuring six. Speed limits are reduced both due to fog or road construction, and are otherwise set at 65 miles per hour east of the Wallace Tunnel, and at 55 miles per hour leading into the tunnel.
Future construction will both expand the Mobile Bayway to eight overall lanes, and bypass the Wallace Tunnel with a new 215 feet high cable-stayed bridge accommodating six lanes of traffic. Planning for the new Mobile River Bridge dates back to at least 2001, but funding issues and opposition pushed back progress for over a decade.
Adam Froehlig attended an ALDOT public hearing on the new span and Mobile Bayway widening project in November 2001. His summary of the meeting was posted at misc.transport.road on November 28, 2001:
The proposed bridge is a cable-stayed bridge, 3 lanes each direction with 10′ shoulders on each side, Y-shaped main piers (as opposed to the H-shaped piers on the Cochrane Bridge to the north), and will be located just south of the Wallace Tunnel. ALDOT’s consultant (Volkner, IIRC), designed it in such a way that there is only one private property (a drydock) that would need to be acquired…the rest of the land is either city-owned or state-owned. From west to east:
The west end of the approach span begins between Virginia St and Texas St, and rises on a 4% grade. It begins parallel to, and outside of, the existing I-10 lanes here. Near the Water St exit, it curves to the right as it continues its ascent. In fact, the EB approach span will go directly over the EB off-ramp to Water St for a short ways.
The main span is 1250′ long, with a minimum clearance of 190′ (commented by one official at the hearing to be the second highest clearance in the US across a navigable channel). Of the two main bridge piers, one will be on land off the west side of the river, while the other is in the river, near the eastern side. The cables will stretch 475′ west of, and 575′ east of, the main piers (asymmetrical due to the Water St. interchange).
East of the main span, the bridge takes two curves to the right, separated by a short straight stretch, coming down on another 4% grade, and ends in the median of the “Bayway”, roughly even with the entrance to the USS Alabama battleship park.
The bridge is built primarily with I-10 through traffic in mind (which comprises 60% of overall I-10 traffic in the area, based on traffic studies). Existing I-10, including the Water St and Bankhead interchanges, as well as the Wallace Tunnel, will remain open, and will serve traffic heading to downtown. No clue yet as to what each route will be signed as.
On the western (Mobile) side, there’ll be some ramp/lane changes. The EB on-ramp from Broad St will be widened to 2 lanes…which, in conjunction with a 5th EB lane that begins just east of the Broad St overpass, will give 7 lanes on the EB approach to the bridge/downtown split. Four lanes will continue to downtown, as is the case today, while the right three lanes split off for the bridge. Westbound, instead of having seven lanes merge into four in a short space (about 1/2 mile), the proposal is to taper off the lanes coming from downtown, one at a time, prior to and at the downtown/bridge merge, in order to minimize the potential bottleneck. The actual gore in both directions will be just north(east) of Texas St. Also, the ramps at Texas St (half-diamond to/from the east) will be removed, and the interchange at Virginia St will be reconstructed into a standard diamond, with the eastern ramps accessible to/from the bridge (but not downtown).
Proposals outlined for the Mobile Bayway in 2001 called for adding the new lanes between the two roadways, and expanding the left-hand shoulder to ten feet from the current 5 foot 3 inch width. The gap between the two viaducts would reduce from 139 foot 3 inches to 73 feet overall, with the distance slightly shorter in width near the Eastern Shore. Interchanges with U.S. 90 and U.S. 98 would be reconstructed, but retain the same configuration in place today.