US Bridges

TR99 over Somonauk Creek

Fair

LaSalle County, Illinois · N4250th E2610 · Structure no. 050354500000000

Built
1995
30 years old
Condition
Fair
inspected June 2024
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
132 ft
3 main spans
Daily traffic
75
2020 count
Owner
Town / Township
Town or Township Highway Agency

About this bridge

TR99 over Somonauk Creek is a prestressed concrete box beam or girders - multiple carrying TR99 over Somonauk Creek in LaSalle County, Illinois. It was built in 1995, so it is 30 years old, younger than the Illinois average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 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 75 vehicles a day, roughly 32% of them trucks, projected to reach 76 by 2046. The structure is 132 ft (40.1 m) long and 24 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesTR99
CrossesSomonauk Creek
LocationN4250th E2610
RouteCounty Highway 0
CountyLaSalle County
StateIllinois
Coordinates41.55231, -88.67491
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating48.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans3
Design loadHS 20
Structure length132 ft (40.1 m)
Longest span50 ft (15.2 m)
Deck width24 ft (7.3 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic75 (2020)
Projected traffic76 by 2046
Trucks32%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerTown or Township Highway Agency
Maintained byTown or Township Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was TR99 over Somonauk Creek built?

It was built in 1995, making it 30 years old in 2025.

What condition is TR99 over Somonauk Creek 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 June 2024.

How much traffic does TR99 over Somonauk Creek carry?

About 75 vehicles per day (2020 count), of which roughly 32% are trucks.

How long is TR99 over Somonauk Creek?

The structure is 132 ft (40.1 m) long with a longest span of 50 ft (15.2 m) and a deck 24 ft wide.

Who owns TR99 over Somonauk Creek?

It is owned by the Town or Township Highway Agency.