I-15 Widening - 9th Ave Undercrossing to 15/78 Separation

I-15/78 Improvements widens a 1.4-mile stretch of I-15, spanning from the 9th Avenue undercrossing to the I-15/SR 78 separation. The project's major components included 11 bridge structures—ten widenings and one new ramp bridge. Notably, two of these bridges were strategically built to significant heights and subsequently lowered into place using 24 hydraulic jacks, ensuring ample vertical clearance from the falsework to the roadway below. The project also entailed the construction of eight cast-in-place retaining walls, totaling over 5,300 cubic yards of concrete, in addition to the establishment of tieback and soldier pile walls. These efforts culminated in the creation of a direct-access ramp facilitating High Occupancy Vehicle (HOV) travelers' access from the city street below.

Additional elements of the project included substantial excavation work, involving 60,000 cubic yards of roadway excavation and a commensurate volume of embankment. Furthermore, 20,000 cubic yards of concrete paving were laid, accompanied by the installation of 20,000 linear feet of concrete barrier. The comprehensive project scope also encompassed various aspects such as maintenance of traffic and associated detours, improvements to local streets, enhancements to on-/off-ramps, storm drainage installation, utility relocation, the construction of new and retrofit bridges, Portland Cement Concrete Pavement (PCCP) paving, early-strength and rapid-set concrete paving, PCCP panel replacement, electrical infrastructure, and the implementation of new freeway signing systems.

The contractual timeline initially spanned 36 months. However, through a collaborative effort with the California Department of Transportation (Caltrans), the project's schedule was condensed to 34 months by identifying time-saving opportunities. The strategic approach involved running two of the three project stages concurrently. Stages 1 and 2 focused on the construction of the outside lanes and shoulders in both the northbound and southbound directions of I-15. Subsequently, Stage 3 involved the transition of traffic to the new outside lanes and the reconstruction of the median, leading to the addition of HOV lanes and the Direct Access Ramp.

This project earned several awards, including the 2012 CA Transportation Foundation Project of the Year and the 2011 Caltrans Partnering Success in Motion Award (Gold Level), highlighting its exceptional contributions to transportation infrastructure.