US Bridges

SH 121 SB over Dart

Fair

Collin County, Texas · 1 MI N of Melissa · Structure no. 180430054903227

Built
2018
7 years old
Condition
Fair
inspected May 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
307 ft
1 main span
Daily traffic
16,527
2011 count
Owner
State
State Highway Agency

About this bridge

SH 121 SB over Dart is a prestressed concrete stringer/multi-beam or girder carrying SH 121 SB over Dart in Collin County, Texas. It was built in 2018, so it is 7 years old, younger than the Texas average of 44.4 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 16,527 vehicles a day, roughly 13% of them trucks, projected to reach 20,163 by 2041. The structure is 307 ft (93.6 m) long and 40 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSH 121 SB
CrossesDart
Location1 MI N of Melissa
RouteState Highway 121
CountyCollin County
StateTexas
Coordinates33.27488, -96.57615
Functional classRural Minor Arterial

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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating60 US tons
Inventory rating36 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadHL 93
Structure length307 ft (93.6 m)
Longest span127 ft (38.7 m)
Deck width40 ft (12.2 m)
Roadway width32 ft (9.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic16,527 (2011)
Projected traffic20,163 by 2041
Trucks13%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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 SH 121 SB over Dart built?

It was built in 2018, making it 7 years old in 2025.

What condition is SH 121 SB over Dart 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 May 2023.

How much traffic does SH 121 SB over Dart carry?

About 16,527 vehicles per day (2011 count), of which roughly 13% are trucks.

How long is SH 121 SB over Dart?

The structure is 307 ft (93.6 m) long with a longest span of 127 ft (38.7 m) and a deck 40 ft wide.

Who owns SH 121 SB over Dart?

It is owned by the State Highway Agency.