US Bridges

Dearborn ST over Main Br Chicago Riv

Fair

Cook County, Illinois · 100 W & 307 N · Structure no. 016601400000000

Built
1963
62 years old
Condition
Fair
inspected September 2024
Type
Movable - Bascule
Steel
Length
341 ft
1 main span
Daily traffic
5,600
2022 count
Owner
City
City or Municipal Highway Agency

About this bridge

Dearborn ST over Main Br Chicago Riv is a steel movable - bascule carrying Dearborn ST over Main Br Chicago Riv in Cook County, Illinois. It was built in 1963, so it is 62 years old, older 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 5,600 vehicles a day, roughly 9% of them trucks, projected to reach 2,879 by 2046. The structure is 341 ft (103.9 m) long and 86 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesDearborn ST
CrossesMain Br Chicago Riv
Location100 W & 307 N
CountyCook County
StateIllinois
Coordinates41.8874, -87.62951
Functional classUrban Collector

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 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 geometry9: Superior to present desirable criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating61.1 US tons
Inventory rating36.4 US tons

Structure

Structure typeMovable - Bascule
MaterialSteel
DeckOpen grating
Main spans1 (+4 approach)
Design loadUnknown
Structure length341 ft (103.9 m)
Longest span235 ft (71.6 m)
Deck width86 ft (26.2 m)
Roadway width56 ft (17.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,600 (2022)
Projected traffic2,879 by 2046
Trucks9%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$3.2 million
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was Dearborn ST over Main Br Chicago Riv built?

It was built in 1963, making it 62 years old in 2025.

What condition is Dearborn ST over Main Br Chicago Riv 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 September 2024.

How much traffic does Dearborn ST over Main Br Chicago Riv carry?

About 5,600 vehicles per day (2022 count), of which roughly 9% are trucks.

How long is Dearborn ST over Main Br Chicago Riv?

The structure is 341 ft (103.9 m) long with a longest span of 235 ft (71.6 m) and a deck 86 ft wide.

Who owns Dearborn ST over Main Br Chicago Riv?

It is owned by the City or Municipal Highway Agency.