US Bridges

State Route 99 NB over M Street

Fair

Merced County, California · 10-MER-099-14.96-MER · Structure no. 39 0134R

Built
1962
63 years old
Condition
Fair
inspected April 2024
Type
Box Beam or Girders - Multiple
Concrete
Length
66 ft
1 main span
Daily traffic
25,500
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 99 NB over M Street is a concrete box beam or girders - multiple carrying State Route 99 NB over M Street in Merced County, California. It was built in 1962, so it is 63 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 25,500 vehicles a day, roughly 20% of them trucks, projected to reach 38,243 by 2046. The structure is 66 ft (20.1 m) long and 40 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

CarriesState Route 99 NB
CrossesM Street
Location10-MER-099-14.96-MER
RouteState Highway 99
Coordinates37.29827, -120.48684
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45 US tons
Inventory rating34.6 US tons

Structure

MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length66 ft (20.1 m)
Longest span65 ft (19.8 m)
Deck width40 ft (12.1 m)
Roadway width37 ft (11.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic25,500 (2009)
Projected traffic38,243 by 2046
Trucks20%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.9 mi (3 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 State Route 99 NB over M Street built?

It was built in 1962, making it 63 years old in 2025.

What condition is State Route 99 NB over M Street in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in April 2024.

How much traffic does State Route 99 NB over M Street carry?

About 25,500 vehicles per day (2009 count), of which roughly 20% are trucks.

How long is State Route 99 NB over M Street?

The structure is 66 ft (20.1 m) long with a longest span of 65 ft (19.8 m) and a deck 40 ft wide.

Who owns State Route 99 NB over M Street?

It is owned by the State Highway Agency.