National Bridge Inventory: New Hampshire
- Of the 2,514 bridges in the state, 215, or 8.6 percent, are classified as structurally deficient. This means one of the key elements is in poor or worse condition.
- This is down from 249 bridges classified as structurally deficient in 2016.
- The deck area of structurally deficient bridges accounts for 6.8 percent of total deck area on all structures.
- 9 of the structurally deficient bridges are on the Interstate Highway System. A total of 85.6 percent of the structurally deficient bridges are not on the National Highway System, which includes the Interstate and other key roads linking major airports, ports, rail and truck terminals.
- 147 bridges are posted for load, which may restrict the size and weight of vehicles crossing the structure.
- The state has identified needed repairs on 2,462 bridges at an estimated cost of $6.0 billion.
- This compares to 2,444 bridges that needed work in 2016.
|County||Year Built||Daily Crossings||Type of Bridge||Location|
|Merrimack||1959||48,774||Urban Interstate||I-89 over South Street|
|Merrimack||1958||46,136||Urban Interstate||I-393,US 4,US202 over I-93|
|Merrimack||1958||46,136||Urban minor arterial||US202 over NHRR,Constitution Av.|
|Merrimack||1980||44,015||Urban Interstate||I-393,US 4,US202 over Fort Eddy Rd|
|Merrimack||1966||25,347||Urban minor arterial||Nh 9(Loudon Road) over Merrimack River|
|Strafford||1957||24,688||Urban freeway/expressway||Nh 16,Sp Tpk NB over Cocheco River|
|Hillsborough||1923||24,531||Urban other principal arterial||US 3,NH 3A over I-293,NH 3A,PAR,Merr R|
|Hillsborough||1956||24,408||Urban Interstate||I-293,NH 3A,Tpk N over Black Brook|
|Strafford||1957||23,907||Urban freeway/expressway||Nh 16,Sp Tpk SB over Cocheco River|
|Strafford||1957||23,012||Urban freeway/expressway||Nh 16,Sp Tpk NB over Nh108,Par(Abd)|
|Grafton||1966||22,596||Urban Interstate||I-89 NB over US 4,NH 10|
|Hillsborough||1956||22,285||Urban Interstate||I-293,NH 3A,Tpk S over Black Brook|
|Strafford||1957||21,551||Urban freeway/expressway||Nh 16,Sp Tpk SB over Nh108,Par(Abd)|
|Grafton||1966||21,530||Urban Interstate||I-89 NB over Connecticut River,Necrr|
|Grafton||1966||20,545||Urban Interstate||I-89 SB over Connecticut River,Necrr|
|Hillsborough||1928||16,809||Urban other principal arterial||Canal Street over Nashua River|
|Rockingham||1935||16,254||Urban other principal arterial||US 1 over Par|
|Rockingham||1936||16,138||Urban other principal arterial||US 1 over Par(Abd)|
|Belknap||1933||15,176||Urban minor arterial||US 3 over Nhrr|
|Hillsborough||1958||14,701||Rural arterial||US202,Nh101 over Contoocook River|
|Hillsborough||1921||14,690||Urban minor arterial||US 3 over Souhegan River|
|Hillsborough||1933||14,392||Urban minor arterial||US 3 over Baboosic Brook|
|Grafton||1977||14,340||Urban minor arterial||US 4,Mechanic St over Mascoma River|
|Belknap||1962||13,715||Rural Interstate||I-93 NB over Salmon Brook|
|Carroll||1955||11,920||Rural arterial||US302,Nh113 over Conway Lake Outlet|
|Type of Bridge||Number of Bridges||Area of All Bridges
|Daily Crossings on All Bridges||Number of Structurally Deficient Bridges||Area of Structurally Deficient Bridges
|Daily Crossings on Structurally Deficient Bridges|
|Rural minor arterial||165||61,088||795,083||9||2,418||46,172|
|Rural major collector||199||67,022||563,335||21||9,652||49,512|
|Rural minor collector||180||36,844||249,769||11||3,786||11,942|
|Rural local road||853||110,671||302,348||97||8,777||41,480|
|Urban other principal arterial||113||162,158||1,885,333||5||11,137||85,553|
|Urban minor arterial||134||104,041||1,538,438||15||13,283||193,776|
|Urban local road||166||47,542||274,981||20||3,484||27,188|
|Type of Work||Number of Bridges||Cost to Repair
|Daily Crossings||Area of Bridges
|Widening & rehabilitation||0||$0||0||0|
|Other structural work||4||$11||11,007||2,210|
About the data:
Data is from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), downloaded on March 11, 2021. Note that specific conditions on bridges may have changed as a result of recent work or updated inspections. Cost estimates were downloaded by ARTBA on March 11, 2021.
Effective January 1, 2018, FHWA changed the definition of structurally deficient as part of the final rule on highway and bridge performance measures, published May 20, 2017 pursuant to the 2012 federal aid highway bill Moving Ahead for Progress in the 21st Century Act (MAP-21). Two measures that were previously used to classify bridges as structurally deficient are no longer used. This includes bridges where the overall structural evaluation was rated in poor or worse condition, or where the adequacy of waterway openings was insufficient.
The new definition limits the classification to bridges where one of the key structural elements—the deck, superstructure, substructure or culverts, are rated in poor or worse condition. During inspection, the conditions of a variety of bridge elements are rated on a scale of 0 (failed condition) to 9 (excellent condition). A rating of 4 is considered “poor” condition.
Cost estimates have been derived by ARTBA, based on 2019 average bridge replacement costs for structures on and off the National Highway System, published by FHWA. Bridge rehabilitation costs are estimated to be 68 percent of replacement costs. A bridge is considered to need repair if the structure has identified repairs as part of the NBI, a repair cost estimate is supplied by the bridge owner or the bridge is classified as structurally deficient. Please note that for a few states, the number of bridges needing to be repaired can vary significantly from year to year, and reflects the data entered by the state.
Bridges are classified by FHWA into types based on the functional classification of the roadway on the bridge. Interstates comprise routes officially designated by the Secretary of Transportation. Other principal arterials serve major centers of urban areas or provide mobility through rural areas. Freeways and expressways have directional lanes generally separated by a physical barrier, and access/egress points generally limited to on- and off-ramps. Minor arterials serve smaller areas and are used for trips of moderate length. Collectors funnel traffic from local roads to the arterial network; major collectors have higher speed limits and traffic volumes and are longer in length and spaced at greater intervals, while minor collectors are shorter and provide service to smaller communities. Local roads do not carry through traffic and are intended for short distance travel.
Compared to 17 in 2019
in the nation in % of structurally deficient bridges
Compared to 43 in 2019
in the nation in # of structurally deficient bridges
Compared to 13 in 2019
in the nation in % of structurally deficient bridge deck area