Marin County Bridge Report Card

Marin County scores 66 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.

D66 / 100

Local infrastructure snapshot

Marin County, California

Marin County has 207 bridges in the National Bridge Inventory, with 16 rated poor and 8 rated scour-critical. Its poor-condition share of 7.7% is above the 4.9% statewide average. Poor-condition bridges carry about 179,256 daily vehicle crossings.

207Total Bridges

16Poor (7.7%)

100Fair (48.3%)

8Scour-Critical

Quote-Ready Local Facts

7.7%of county bridges are in poor condition, compared with 4.9% statewide and 6.7% nationally.

179,256daily vehicle crossings are on poor-condition bridges in the county.

8bridges are rated scour-critical, or 3.9% of the county bridge inventory.

Copyable Facts for Reporters

BridgeLookup.com gives Marin County a Bridge Condition Exposure Score of 66/100 (D). The county has 207 bridges in the National Bridge Inventory, including 16 in poor condition and 8 rated scour-critical. Poor-condition bridges carry about 179,256 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	7.7%	15.5
Poor-condition traffic exposure	25	3.6% of measured traffic	2.7
Scour-critical bridge share	20	3.9%	7.7
Average age vs national baseline	10	67 years vs 48 nationally	7.7
Traffic-data completeness	5	4,971,608 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	7.7%
State Poor-Condition Share	4.9%
National Poor-Condition Share	6.7%
County Scour-Critical Share	3.9%
Average Bridge Age	67 years
Poor-Condition Traffic Exposure	179,256 vehicles/day

Bridges to Watch

Busiest Poor-Condition BridgeU.s. Highway 101 over Novato Creek — 61,500 vehicles/day Oldest Listed BridgeU.s. Highway 101 over Irwin Creek — built in 1895 All County BridgesBrowse every bridge record in Marin County.

Top Bridges to Watch in Marin County

Bridge	Reason	Condition	Daily Traffic	Year Built
Novato BLVD over Bowman Canyon	Poor condition + traffic exposure	Poor	3,056	1948
Marshall Petlum RD over Salmon Creek	Poor condition + traffic exposure	Poor	328	1931
U.s. Highway 101 over Novato Creek	Poor condition + traffic exposure	Poor	61,500	1974
Sir Francis Drake over Lagunitas Creek	Poor condition + traffic exposure	Poor	25,582	1964
U.s. Highway 101 over Corte Madera CR & EB Sfd	Poor condition + traffic exposure	Poor	19,700	1959
Freitas PKWY over U.s. Highway 101	Poor condition + traffic exposure	Poor	18,000	1960
Ignacio Boulevard over U.s. Highway 101	Poor condition + traffic exposure	Poor	12,900	1964
Lincoln AVE over San Rafael Creek	Poor condition + traffic exposure	Poor	11,601	1959
Novato BLVD over Novato Creek	Poor condition + traffic exposure	Poor	10,024	1969
State Route 1 over Redwood Creek	Poor condition + traffic exposure	Poor	3,800	1926

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.