US Bridges

Manter Mill Road over Cohas Brook

Good

Rockingham County, New Hampshire · 0.25ML Junc. Old Derry RD · Structure no. 015400890018700

Built
2000
25 years old
Condition
Good
inspected September 2023
Type
Culvert
Concrete
Length
34 ft
1 main span
Daily traffic
511
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Manter Mill Road over Cohas Brook is a concrete culvert carrying Manter Mill Road over Cohas Brook in Rockingham County, New Hampshire. It was built in 2000, so it is 25 years old, younger than the New Hampshire average of 56.9 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 511 vehicles a day, projected to reach 756 by 2043. The structure is 34 ft (10.4 m) long. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesManter Mill Road
CrossesCohas Brook
Location0.25ML Junc. Old Derry RD
CountyRockingham County
StateNew Hampshire
Coordinates42.93793, -71.3702
Functional classUrban Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Channel and channel protection8 Very GoodNo problems noted.
Culvert8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating60.1 US tons
Inventory rating36 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans1
Design loadHS 20
Structure length34 ft (10.4 m)
Longest span32 ft (9.8 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic511 (2023)
Projected traffic756 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$314,000 (2025 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Manter Mill Road over Cohas Brook built?

It was built in 2000, making it 25 years old in 2025.

What condition is Manter Mill Road over Cohas Brook in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in September 2023.

How much traffic does Manter Mill Road over Cohas Brook carry?

About 511 vehicles per day (2023 count).

How long is Manter Mill Road over Cohas Brook?

The structure is 34 ft (10.4 m) long with a longest span of 32 ft (9.8 m).

Who owns Manter Mill Road over Cohas Brook?

It is owned by the City or Municipal Highway Agency.