National Bridge Inventory: New Hampshire



  • Of the 2,494 bridges in the state, 224, or 9.0 percent, are classified as structurally deficient. This means one of the key elements is in poor or worse condition.
  • This is down from 260 bridges classified as structurally deficient in 2014.
  • 13 of the structurally deficient bridges are on the Interstate Highway System.
  • 160 bridges are posted for load, which may restrict the size and weight of vehicles crossing the structure.
  • The state has identified needed repairs on 2,444 bridges at an estimated cost of $3.7 billion.
  • This compares to 2,437 bridges that needed work in 2014.

County Year Built Daily Crossings Type of Bridge Location
Merrimack 1959 42,600 Urban Interstate I-89 over South Street
Merrimack 1980 41,300 Urban Interstate I-393,US 4,US202 over Fort Eddy Rd
Merrimack 1958 41,300 Urban Interstate I-393,US 4,US202 over I-93
Hillsborough 1960 41,000 Urban Interstate I-293 SB,Nh101 EB over Merrimack River,Par
Merrimack 1958 36,488 Urban Interstate I-93,Fee Tpk SB over Hall Street
Merrimack 1958 32,900 Urban minor arterial US202 over NHRR,Constitution Av.
Rockingham 1962 32,000 Urban other principal arterial Nh102 over I-93
Hillsborough 1923 25,000 Urban other principal arterial US 3,NH 3A over I-293,NH 3A,PAR,Merr R
Hillsborough 1956 22,000 Urban Interstate I-293,NH 3A,Tpk S over Black Brook
Hillsborough 1956 22,000 Urban Interstate I-293,NH 3A,Tpk N over Black Brook
Rockingham 1940 21,000 Urban freeway/expressway US 1 Bypass over Hodgson Brook
Grafton 1966 20,433 Urban Interstate I-89 SB over Connecticut River,Necrr
Grafton 1966 20,433 Urban Interstate I-89 NB over Connecticut River,Necrr
Cheshire 1961 19,000 Urban other principal arterial Nh 12 over Beaver Brook
Grafton 1966 17,500 Urban Interstate I-89 NB over US 4,NH 10
Hillsborough 1928 17,000 Urban other principal arterial Canal Street over Nashua River
Rockingham 1935 16,290 Urban other principal arterial US 1 over Par
Hillsborough 1921 16,000 Urban minor arterial US 3 over Souhegan River
Rockingham 1936 16,000 Urban other principal arterial US 1 over Par(Abd)
Hillsborough 1958 15,000 Rural arterial US202,Nh101 over Contoocook River
Merrimack 1966 15,000 Urban minor arterial Nh 9(Loudon Road) over Merrimack River
Merrimack 1960 14,428 Urban Interstate I-93 SB over NHRR,Winnipesaukee River
Merrimack 1960 14,428 Urban Interstate I-93 NB over NHRR,Winnipesaukee River
Hillsborough 1933 14,197 Urban minor arterial US 3 over Baboosic Brook
Grafton 1949 14,000 Urban minor arterial Nh 12A over Nhrr
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 207 120,791 1,840,003 1 99 12,500
Rural arterial 123 56,746 1,043,188 11 5,574 95,100
Rural minor arterial 164 60,901 758,084 9 3,359 45,860
Rural major collector 199 66,947 524,174 22 9,582 50,470
Rural minor collector 178 36,552 224,021 13 3,182 19,740
Rural local road 840 109,401 344,352 99 8,250 46,000
Urban Interstate 161 205,734 5,260,310 12 18,005 333,910
Urban freeway/expressway 92 105,461 2,775,653 2 9,602 32,000
Urban other principal arterial 113 159,276 1,751,773 8 13,152 146,415
Urban minor arterial 133 101,362 1,434,359 15 13,282 168,656
Urban collector 118 58,141 631,990 12 5,390 58,600
Urban local road 166 48,912 273,970 20 3,841 28,320
Total 2,494 1,130,225 16,861,877 224 93,318 1,037,571
Type of Work Number of Bridges Cost to Repair
(in millions)
Daily Crossings Area of Bridges
(sq. meters)
Bridge replacement 2,435 $3,718 16,848,115 1,124,525
Widening & rehabilitation 0 $0 0 0
Rehabilitation 4 $0 135 539
Deck rehabilitation/replacement 1 $0 50 180
Other structural work 4 $0 11,007 2,209
Total 2,444 $3,718 16,859,307 1,127,453

About the data:

Data from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), released March 15, 2019. 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 2017 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 cost estimate is supplied by the bridge owner or the bridge is classified as structurally deficient.

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.

17
from 18 in 2017

in the nation in % of structurally deficient bridges

1. Rhode Island 23.1%
16. Massachusetts 9.2%
17. New Hampshire 9.0%
18. Nebraska 8.8%

43
from 43 in 2017

in the nation in # of structurally deficient bridges

1. Iowa 4,675
42. New Mexico 232
43. New Hampshire 224
44. Rhode Island 180
Full State Ranking

  • Source: Bridge data is from the 2018 National Bridge Inventory ASCII files, released by the Federal Highway Administration on March 14, 2019. Note that specific conditions on bridges may have changed as a result of recent work. ARTBA is a non-partisan federation whose primary goal is to aggressively grow and protect transportation infrastructure investment to meet the public and business demand for safe and efficient travel.
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