National Bridge Inventory: New Hampshire



  • Of the 2,527 bridges in the state, 194, or 7.7 percent, are classified as structurally deficient. This means one of the key elements is in poor or worse condition.
  • This is down from 223 bridges classified as structurally deficient in 2017.
  • The deck area of structurally deficient bridges accounts for 6.6 percent of total deck area on all structures.
  • 11 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.
  • 138 bridges are posted for load, which may restrict the size and weight of vehicles crossing the structure.
  • The state has identified needed repairs on 2,473 bridges at an estimated cost of $4.9 billion.
  • This compares to 2,435 bridges that needed work in 2017.

County Year Built Daily Crossings Type of Bridge Location
Merrimack 1959 51,032 Urban Interstate I-89 over South Street
Merrimack 1958 46,690 Urban Interstate I-393,US 4,US202 over I-93
Merrimack 1958 46,690 Urban minor arterial US202 over NHRR,Constitution Av.
Merrimack 1980 43,007 Urban Interstate I-393,US 4,US202 over Fort Eddy Rd
Merrimack 1966 25,651 Urban minor arterial Nh 9(Loudon Road) over Merrimack River
Hillsborough 1956 24,701 Urban Interstate I-293,NH 3A,Tpk N over Black Brook
Hillsborough 1923 24,531 Urban other principal arterial US 3,NH 3A over I-293,NH 3A,PAR,Merr R
Strafford 1957 24,194 Urban freeway/expressway Nh 16,Sp Tpk SB over Cocheco River
Strafford 1957 23,122 Urban freeway/expressway Nh 16,Sp Tpk NB over Cocheco River
Strafford 1957 22,715 Urban freeway/expressway Nh 16,Sp Tpk NB over Nh108,Par(Abd)
Hillsborough 1956 22,552 Urban Interstate I-293,NH 3A,Tpk S over Black Brook
Grafton 1966 22,284 Urban Interstate I-89 NB over US 4,NH 10
Grafton 1966 21,853 Urban Interstate I-89 NB over Connecticut River,Necrr
Strafford 1957 21,847 Urban freeway/expressway Nh 16,Sp Tpk SB over Nh108,Par(Abd)
Merrimack 1959 20,920 Rural Interstate I-89 SB over Turkey Pond
Grafton 1966 20,853 Urban Interstate I-89 SB over Connecticut River,Necrr
Merrimack 1959 20,535 Rural Interstate I-89 NB over Turkey Pond
Hillsborough 1928 16,809 Urban other principal arterial Canal Street over Nashua River
Rockingham 1936 16,332 Urban other principal arterial US 1 over Par(Abd)
Rockingham 1935 16,139 Urban other principal arterial US 1 over Par
Hillsborough 1958 14,848 Rural arterial US202,Nh101 over Contoocook River
Hillsborough 1933 14,565 Urban minor arterial US 3 over Baboosic Brook
Grafton 1977 14,555 Urban minor arterial US 4,Mechanic St over Mascoma River
Belknap 1962 14,003 Rural Interstate I-93 NB over Salmon Brook
Hillsborough 1921 13,596 Urban minor arterial US 3 over Souhegan River
Type of Bridge Number of Bridges Area of All Bridges
(sq. meters)
Daily Crossings on All Bridges Number of Structurally Deficient Bridges Area of Structurally Deficient Bridges
(sq. meters)
Daily Crossings on Structurally Deficient Bridges
Rural Interstate 208 119,435 2,013,789 3 2,646 55,458
Rural arterial 124 56,680 1,169,357 8 3,564 77,740
Rural minor arterial 165 61,121 796,899 8 2,355 43,177
Rural major collector 199 67,159 563,167 20 9,442 47,767
Rural minor collector 180 36,983 251,978 11 3,891 12,242
Rural local road 863 112,502 306,739 90 10,062 45,943
Urban Interstate 163 209,873 5,312,402 8 9,465 252,972
Urban freeway/expressway 92 118,711 2,944,142 4 4,431 91,878
Urban other principal arterial 112 164,665 1,892,661 5 11,137 85,632
Urban minor arterial 134 104,291 1,543,130 13 12,748 172,585
Urban collector 119 58,185 669,013 9 4,924 54,145
Urban local road 168 47,801 276,642 15 2,034 19,937
Total 2,527 1,157,406 17,739,919 194 76,700 959,476
Type of Work Number of Bridges Cost to Repair
(in millions)
Daily Crossings Area of Bridges
(sq. meters)
Bridge replacement 2,458 $4,885 17,725,152 1,151,371
Widening & rehabilitation 0 $0 0 0
Rehabilitation 10 $3 454 794
Deck rehabilitation/replacement 1 $1 50 180
Other structural work 4 $8 11,007 2,210
Total 2,473 $4,896 17,736,663 1,154,555

About the data:

Data is from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), downloaded on January 3, 2022. 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 January 3, 2022.

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 2020 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.

18
Compared to 17 in 2020

in the nation in % of structurally deficient bridges

1. West Virginia 20.4%
17. Alaska 8.2%
18. New Hampshire 7.7%
19. Hawaii 7.5%

43
Compared to 43 in 2020

in the nation in # of structurally deficient bridges

1. Iowa 4,504
42. New Mexico 208
43. New Hampshire 194
44. Rhode Island 136

19
Compared to 13 in 2020

in the nation in % of structurally deficient bridge deck area

1. Rhode Island 19.5%
18. New Jersey 6.8%
19. New Hampshire 6.6%
20. Washington 6.4%
Full State Ranking

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  • Source: Data is from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), downloaded on January 3, 2022. Note that specific conditions on bridges may have changed as a result of recent work or updated inspections.

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