US Bridges

Twombly RD over I-39 & US 51

Fair

Ogle County, Illinois · 1 MI N of Il 38 · Structure no. 071005700000000

Built
1980
45 years old
Condition
Fair
inspected November 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
259 ft
2 main spans
Daily traffic
600
2022 count
Owner
State
State Highway Agency

About this bridge

Twombly RD over I-39 & US 51 is a prestressed concrete continuous stringer/multi-beam or girder carrying Twombly RD over I-39 & US 51 in Ogle County, Illinois. It was built in 1980, so it is 45 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 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 600 vehicles a day, roughly 16% of them trucks, projected to reach 728 by 2046. The structure is 259 ft (78.9 m) long and 30 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesTwombly RD
CrossesI-39 & US 51
Location1 MI N of Il 38
RouteCounty Highway 0
CountyOgle County
StateIllinois
Coordinates41.94901, -89.02409
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionNovember 2023
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 rating62.5 US tons
Inventory rating38.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans2 (+2 approach)
Design loadHS 20
Structure length259 ft (78.9 m)
Longest span106 ft (32.2 m)
Deck width30 ft (9.1 m)
Roadway width27 ft (8.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic600 (2022)
Projected traffic728 by 2046
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

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 Twombly RD over I-39 & US 51 built?

It was built in 1980, making it 45 years old in 2025.

What condition is Twombly RD over I-39 & US 51 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 November 2023.

How much traffic does Twombly RD over I-39 & US 51 carry?

About 600 vehicles per day (2022 count), of which roughly 16% are trucks.

How long is Twombly RD over I-39 & US 51?

The structure is 259 ft (78.9 m) long with a longest span of 106 ft (32.2 m) and a deck 30 ft wide.

Who owns Twombly RD over I-39 & US 51?

It is owned by the State Highway Agency.