Why Is the Montana/Sepulveda Intersection Significant?

Sitting a stone’s throw east of the I-405 freeway and the Brentwood Glen community, the Montana Av/Sepulveda Bl intersection continues its transformation by the I-405 Sepulveda Pass Improvements Project.

A center of daytime and nighttime construction for months, the Montana Av/Sepulveda Bl intersection illustrates:

• Why Sepulveda Bl will be shifted east.
• How an additional northbound lane will be added.
• Why so many tasks must be completed before that lane can be built.

Although the new northbound High-Occupancy Vehicle (HOV) lane will run along the median—as do all California HOV lanes—that extra lane will actually be added by moving miles of the nation’s busiest stretch of freeway to the east. Restriping the northbound lanes will magically create the HOV lane at the freeway’s center.

The freeway undercrossing at Montana must be widened to accommodate the new lane, just as the Constitution, Ohio, and Santa Monica undercrossings must be widened. Part of this work entails demolishing a retaining wall and adding a retaining wall to support the new number 5 lane as it winds north toward Sunset Bl.

To add that lane, Sepulveda Bl needs to be moved east. To move Sepulveda Bl east, walls must be built to support the hillsides to the east.

A 30-second walk north of the Montana/Sepulveda intersection rise two long and tall walls. One rises north of Homedale and one rises south of Homedale.

If you have driven by the walls (named 1720 and 1730 by the project team) in the last several months, you likely have noticed that something is missing. That “something” is a concrete wall that ran along the east edge of Sepulveda Bl, separating the arterial from the homes that overlooked it.

The old wall, which ran 2,211 feet long, has been replaced by the taller tie-back walls adjoining the homes east of Sepulveda Bl. (The new walls range from 15 to 55 feet tall.)

Why tear down the existing wall and build the new, higher walls? Because the new course for Sepulveda Bl flows over the old wall’s location. (Other areas of the project have ample room between Sepulveda Bl and the I-405 to add the new lane without pushing Sepulveda Bl east.)

To add another wrinkle to this mammoth effort, dozens of utilities must be moved before Sepulveda Bl can be moved east. With this effort, the Montana/Sepulveda intersection becomes the gateway for connecting relocated utilities with existing utilities. Relocating the utilities saves them from being buried under the new freeway lane.

Figure 1 shows the existing Montana undercrossing (a bridge over a street is referred to as an “undercrossing”), while Figure 2 shows the Montana undercrossing when it is widened and completed. The dark pavement at the lower edge of the freeway indicates the new number 5 lane and auxiliary lane.

Figure 1—Before construction began on the Montana undercrossing, this was the configuration of the complex Montana Av/Sepulveda Bl intersection.

Figure 2 shows the new lane and relocated shoulder. So where is the brand new HOV lane? It takes its place near the freeway median.

Figure 2—The completed Montana undercrossing carries the new number 5 lane and auxiliary lane. Notice the Montana northbound off-ramp has disappeared in the final configuration.

Ned Racine