SL 88 Segments 3A, 3B, and 3C, TxDOT
Lubbock, TX

IEA served as the prime consultant responsible for providing plans, specifications, and estimates (PS&E) services for SL 88 Segment 3.

The proposed SL 88 freeway consisted of 12 miles of 6-lane controlled access highway (3 lanes in both the Eastbound and Westbound direction) along with auxiliary lanes, multiple ramps, and 3-lane parallel frontage roads in each direction.

Bridges:

IEA was responsible for the PS&E of 2 DC bridges (South to West DC and East to North DC) and 2 mainlane bridges (designed with square aesthetic columns for vehicular collision) on a multi-level interchange south of downtown Lubbock, TX, where the existing US 87 and proposed Loop 88 intersect.  IEA developed a bent configuration for 6-lane freeway with a 5-level interchange, custom elastomeric bearings for fixed supports, and structural gore details for crash cushion backwalls.  Our team designed superstructure for curved concrete and continuous steel units for Level 3 and 5 DC, aesthetic Cantilever Overhead Sign Structure (COSS) and Overhead Sign Bridge (OSB) columns and foundations, and concrete and mass concrete substructures for DCs including inverted-T bent caps, straddle bents, hammerhead columns with aesthetic treatment, and 2-,4-, and 5-shaft footings. 

Drainage:

IEA overcame complex drainage challenges for SL 88 Segment 3 by addressing two significant playa lakes near the SL 88 and US 87 intersection. To mitigate flooding and balance the floodplain, our team designed four large detention ponds strategically placed at the intersection's corners. Using advanced ICPR modeling software, we analyzed stormwater flow, met the City of Lubbock's drainage guidelines, and tackled the unique hydrological complexities of the area. Additionally, IEA designed 14 sewer systems, replaced three existing culverts and established new connections to ensure efficient and sustainable drainage solutions.

Traffic/Illumination:

IEA design leads coordinated to design of Metal beam guard fences (MBGF) at Large Guide Signs and Dynamic Message Signs and CCTV poles. The overhead signs for this project faced challenges due to tall walls and limited space between adjacent on and off-ramps. IEA optimized the number of sign locations/structures by strategically placing/combining structures in both directions into a single span OSB structure.

IEA provided continuous illumination throughout the proposed corridor using conventional light poles mounted on media barriers as well as additional lighting at critical project turnarounds and project limits/ transition with the existing roadway to enhance safety.