Jefferson County Bridge Report Card
Jefferson County scores 87 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Jefferson County, Montana
Jefferson County has 136 bridges in the National Bridge Inventory, with 7 rated poor and 1 rated scour-critical. Its poor-condition share of 5.1% is at or below the 7.4% statewide average. Poor-condition bridges carry about 3,299 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Jefferson County a Bridge Condition Exposure Score of 87/100 (B). The county has 136 bridges in the National Bridge Inventory, including 7 in poor condition and 1 rated scour-critical. Poor-condition bridges carry about 3,299 daily vehicle crossings. Poor condition does not mean unsafe; bridges judged unsafe are closed or restricted by transportation agencies.
How the Score Breaks Down
| Factor | Weight | County Value | Penalty |
|---|---|---|---|
| Poor-condition bridge share | 40 | 5.1% | 10.3 |
| Poor-condition traffic exposure | 25 | 1.3% of measured traffic | 1.0 |
| Scour-critical bridge share | 20 | 0.7% | 1.5 |
| Average age vs national baseline | 10 | 49 years vs 48 nationally | 0.3 |
| Traffic-data completeness | 5 | 248,257 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 | 5.1% |
| State Poor-Condition Share | 7.4% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 0.7% |
| Average Bridge Age | 49 years |
| Poor-Condition Traffic Exposure | 3,299 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Jefferson County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| Sleepy Hollow LN over Prickly Pear Creek | Poor condition + traffic exposure | Poor | 100 | 2010 |
| Mt 55 over Fish Creek | Poor condition + traffic exposure | Poor | 1,858 | 1953 |
| Mt HWY 2 over Rr 061 | Poor condition + traffic exposure | Poor | 1,001 | 1932 |
| E Elk Park RD over Bison Creek 016 | Poor condition + traffic exposure | Poor | 100 | 1927 |
| I 15 Frontage RD over Cataract Creek 030 | Poor condition + traffic exposure | Poor | 100 | 1933 |
| I 15 Frontage RD over Basin Creek 041 | Poor condition + traffic exposure | Poor | 100 | 1985 |
| Mcclellean Ck Road over Mcclellan Creek | Poor condition + traffic exposure | Poor | 40 | 1959 |
| I 15 over Prickly Pear Creek | High traffic | Fair | 5,987 | 1969 |
| I 15 over Prickly Pear Creek | High traffic | Fair | 5,987 | 1969 |
| S 518 over Int Montana City-i 15 | High traffic | Good | 5,885 | 1968 |
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.