In 1997, Caltrans and the L.A. Department of Transportation (LADOT) performed a feasibility study to determine the best means of reducing congestion at the 101 and 405 interchange. One mitigation was the so-called gap closure/Flyunder project to improve freeway access from Sepulveda Boulevard and to ease the transition onto the connector.
The project extends the current auxiliary lane on the northbound I-405 past the Greanleaf off-ramp to the U.S. 101 connector. This project will also close the loop on-ramp from eastbound Ventura Boulevard and construct a bypass of the Ventura Boulevard/Sepulveda Boulevard intersection using Dickens Street. The Sepulveda Boulevard on-ramp will be reconfigured to separate the U.S. 101 connector on-ramps from the northbound I-405 on-ramp. The City of Los Angeles' Sepulveda Boulevard widening project is being combimned with this project.
This project will enhance safety by reducing the need to cross several lanes of traffic to access the connector. Combined with the I-405 auxiliary lane and the connector widening projects, completed in 2003, the gap closure project will increase freeway capacity, reduce congestion and improve traffic flow at one of the busiest interchanges in the state.