Granite County Bridge Report Card

Granite County scores 58 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.

F58 / 100

Local infrastructure snapshot

Granite County, Montana

Granite County has 73 bridges in the National Bridge Inventory, with 9 rated poor and 3 rated scour-critical. Its poor-condition share of 12.3% is above the 7.4% statewide average. Poor-condition bridges carry about 15,347 daily vehicle crossings.

73Total Bridges

9Poor (12.3%)

36Fair (49.3%)

3Scour-Critical

Quote-Ready Local Facts

12.3%of county bridges are in poor condition, compared with 7.4% statewide and 6.7% nationally.

15,347daily vehicle crossings are on poor-condition bridges in the county.

3bridges are rated scour-critical, or 4.1% of the county bridge inventory.

Copyable Facts for Reporters

BridgeLookup.com gives Granite County a Bridge Condition Exposure Score of 58/100 (F). The county has 73 bridges in the National Bridge Inventory, including 9 in poor condition and 3 rated scour-critical. Poor-condition bridges carry about 15,347 daily vehicle crossings. Poor condition does not mean unsafe; bridges judged unsafe are closed or restricted by transportation agencies.

Download all county report-card scores as CSV.

How the Score Breaks Down

Factor	Weight	County Value	Penalty
Poor-condition bridge share	40	12.3%	24.7
Poor-condition traffic exposure	25	10.7% of measured traffic	8.0
Scour-critical bridge share	20	4.1%	8.2
Average age vs national baseline	10	51 years vs 48 nationally	1.5
Traffic-data completeness	5	143,809 measured daily crossings	0.0

Score = 100 minus weighted penalties. The score is a comparative research signal, not an official safety rating. Read the full methodology.

County Comparisons

County Poor-Condition Share	12.3%
State Poor-Condition Share	7.4%
National Poor-Condition Share	6.7%
County Scour-Critical Share	4.1%
Average Bridge Age	51 years
Poor-Condition Traffic Exposure	15,347 vehicles/day

Bridges to Watch

Busiest Poor-Condition BridgeI 90 over Clark Fork River — 13,081 vehicles/day Oldest Listed BridgeMany Glacier Road over Windy Creek — built in 1931 All County BridgesBrowse every bridge record in Granite County.

Top Bridges to Watch in Granite County

Bridge	Reason	Condition	Daily Traffic	Year Built
Marshall Creek RD over Rock Creek	Poor condition + traffic exposure	Poor	161	1959
No Data Entered over Swamp Gul	Poor condition + traffic exposure	Poor	50	1987
I 90 over Clark Fork River	Poor condition + traffic exposure	Poor	13,081	1970
S 1 over Clark Fork	Poor condition + traffic exposure	Poor	1,354	1966
S Main Street over Clark Fork River 020	Poor condition + traffic exposure	Poor	371	1934
Bear Gulch RD over Clark Fork River 002	Poor condition + traffic exposure	Poor	130	1986
I 90 over Antelope Creek	Poor condition + traffic exposure	Poor	100	1971
No Data Entered over Boulder CR	Poor condition + traffic exposure	Poor	50	1949
No Data Entered over Ross Fork	Poor condition + traffic exposure	Poor	50	1967
Many Glacier Road over Windy Creek	Scour-critical foundation rating	Fair	452	1931

Important safety note

Poor condition does not mean a bridge is unsafe. It means at least one major component has significant deterioration and the bridge is a priority for maintenance, repair, or replacement. Bridges judged unsafe are closed or restricted by transportation agencies.