National Bridge Inventory: New Hampshire



  • The state has identified needed repairs on 2,498 bridges.
  • This compares to 2,473 bridges that needed work in 2021.
  • Over the life of the IIJA, New Hampshire will receive a total of $225.0 million in bridge formula funds, which will help make needed repairs.
  • New Hampshire currently has access to $180.0 million of that total, and has committed $59.9 million towards 9 projects as of June 2025.
  • Of the 2,549 bridges in the state, 192, or 7.5 percent, are classified as structurally deficient. This means one of the key elements is in poor or worse condition.
  • This is down from 194 bridges classified as structurally deficient in 2021.
  • The deck area of structurally deficient bridges accounts for 5.6 percent of total deck area on all structures.

Top Most Traveled Structurally Deficient Bridges in New Hampshire

County Year Built Daily Crossings Type of Bridge Location
Merrimack 1959 46,612 Urban Interstate I-89 over South Street
Hillsborough 1956 46,106 Urban Interstate I-293,Fee Tpk over Stark Way
Merrimack 1958 45,555 Urban minor arterial US202 over NHRR,Constitution Av.
Hillsborough 1954 44,365 Urban freeway/expressway Fee Tpk SB over Pennichuck Brook
Merrimack 1980 40,527 Urban Interstate I-393,US 4,US202 over Fort Eddy Rd
Hillsborough 1956 24,101 Urban Interstate I-293,NH 3A,Tpk N over Black Brook
Merrimack 1966 23,721 Urban minor arterial Nh 9(Loudon Road) over Merrimack River
Strafford 1957 23,607 Urban freeway/expressway Nh 16,Sp Tpk SB over Cocheco River
Strafford 1957 22,560 Urban freeway/expressway Nh 16,Sp Tpk NB over Cocheco River
Merrimack 1958 22,391 Urban Interstate I-393,US 4,US202 over I-93
Grafton 1966 22,288 Urban Interstate I-89 NB over Connecticut River,Necrr
Strafford 1957 22,163 Urban freeway/expressway Nh 16,Sp Tpk NB over Nh108,CSX(Abd)
Hillsborough 1956 22,005 Urban Interstate I-293,NH 3A,Tpk S over Black Brook
Strafford 1957 21,323 Urban freeway/expressway Nh 16,Sp Tpk SB over Nh108,CSX(Abd)
Grafton 1966 21,268 Urban Interstate I-89 SB over Connecticut River,Necrr
Merrimack 1959 20,703 Rural Interstate I-89 SB over Turkey Pond
Merrimack 1959 20,387 Rural Interstate I-89 NB over Turkey Pond
Rockingham 1959 17,736 Urban minor arterial Nh 33 over Winnicut River
Rockingham 1935 15,436 Urban other principal arterial US 1 over CSX
Strafford 1951 14,407 Urban other principal arterial Nh125 over Isinglass River
Rockingham 1936 14,314 Urban other principal arterial US 1 over CSX(Abd)
Strafford 1968 13,387 Urban other principal arterial US 4 over Nh155A
Hillsborough 1970 13,150 Urban other principal arterial Salmon Street EB over Merrimack R,CSX,Rd,Ramp
Hillsborough 1933 13,024 Urban minor arterial US 3 over Baboosic Brook
Grafton 1977 12,803 Urban minor arterial US 4,Mechanic St over Mascoma River

Bridge Inventory: New Hampshire

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 188 105,866 1,735,089 2 2,547 41,090
Rural arterial 133 59,556 1,443,551 3 493 21,376
Rural minor arterial 158 60,394 720,605 9 2,292 28,955
Rural major collector 212 81,683 642,903 25 12,358 76,347
Rural minor collector 177 34,581 221,210 11 3,274 13,822
Rural local road 858 110,731 281,480 90 10,013 27,831
Urban Interstate 183 223,464 5,593,001 8 9,113 245,298
Urban freeway/expressway 84 131,600 2,659,889 5 4,732 134,018
Urban other principal arterial 114 151,002 1,752,928 6 4,968 82,232
Urban minor arterial 138 103,660 1,430,411 14 11,900 182,984
Urban collector 133 62,845 637,292 6 1,695 23,309
Urban local road 171 44,800 241,402 13 1,800 9,639
Total 2,549 1,170,180 17,359,761 192 65,186 886,901

Proposed Bridge Work

Type of Work Number of Bridges Cost to Repair
(in millions)
Daily Crossings Area of Bridges
(sq. meters)
Bridge replacement 2,484 $7,401 17,345,110 1,164,175
Widening & rehabilitation 0 $0 0 0
Rehabilitation 8 $6 345 771
Deck rehabilitation/replacement 1 $1 50 180
Other structural work 5 $17 11,061 2,324
Total 2,498 $7,425 17,356,566 1,167,450

About the data:

Data and cost estimates are from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), downloaded on June 24, 2025. Note that specific conditions on bridges may have changed as a result of recent work or updated inspections.

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 2023 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.

15
Compared to 18 in 2024

in the nation in % of structurally deficient bridges

1. Iowa 19.0%
14. Missouri 9.0%
15. New Hampshire 8.0%
16. Oklahoma 8.0%

42
Compared to 42 in 2024

in the nation in # of structurally deficient bridges

1. Iowa 4,424
41. Connecticut 209
42. New Hampshire 192
43. New Mexico 172

25
Compared to 16 in 2024

in the nation in % of structurally deficient bridge deck area

1. West Virginia 13.0%
24. North Carolina 6.0%
25. New Hampshire 6.0%
26. North Dakota 5.0%
Full State Ranking

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  • Source: Data is from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), downloaded on June 24, 2025. Note that specific conditions on bridges may have changed as a result of recent work or updated inspections.

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