US Bridges

U.S. Highway 101 over US 101 on & Off Ramps

Good

Marin County, California · 04-MRN-101-1.68-SAUS · Structure no. 27 0067

Built
1954
71 years old
Condition
Good
inspected May 2024
Type
Slab
Concrete
Length
40 ft
1 main span
Daily traffic
106,000
2009 count
Owner
State
State Highway Agency

About this bridge

U.S. Highway 101 over US 101 on & Off Ramps is a concrete slab carrying U.S. Highway 101 over US 101 on & Off Ramps in Marin County, California. It was built in 1954, so it is 71 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 106,000 vehicles a day, roughly 1% of them trucks, projected to reach 146,640 by 2042. The structure is 40 ft (12.2 m) long and 122 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

CarriesU.S. Highway 101
CrossesUS 101 on & Off Ramps
Location04-MRN-101-1.68-SAUS
RouteU.S. Route 101
Coordinates37.85285, -122.49224
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating110 US tons
Inventory rating73.5 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length40 ft (12.2 m)
Longest span37 ft (11.4 m)
Deck width122 ft (37.3 m)
Roadway width116 ft (35.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic106,000 (2009)
Projected traffic146,640 by 2042
Trucks1%
Lanes on structure8
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was U.S. Highway 101 over US 101 on & Off Ramps built?

It was built in 1954, making it 71 years old in 2025.

What condition is U.S. Highway 101 over US 101 on & Off Ramps in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in May 2024.

How much traffic does U.S. Highway 101 over US 101 on & Off Ramps carry?

About 106,000 vehicles per day (2009 count), of which roughly 1% are trucks.

How long is U.S. Highway 101 over US 101 on & Off Ramps?

The structure is 40 ft (12.2 m) long with a longest span of 37 ft (11.4 m) and a deck 122 ft wide.

Who owns U.S. Highway 101 over US 101 on & Off Ramps?

It is owned by the State Highway Agency.