Structure M170312XGDOTNBI · Essex County, MA
Carries I 495 SB over St110 /st113/merrimack, At Merrimac River.
172 ft end to end, longest span 68 ft: about 2 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a multi-beam bridge.
| State | Massachusetts |
| County | Essex |
| Location | At Merrimac River |
| Carries | I 495 SB |
| Crosses | St110 /st113/merrimack |
| Coordinates | 42.75364, -71.12901 |
| Material | Steel |
| Design | Stringer/Multi-beam |
| Total Length | 172.2 ft (52.5 m) |
| Max Span | 67.9 ft (20.7 m) |
| Deck Width | 52.2 ft (15.9 m) |
| Deck Area | 834.8 sq m |
| Main Spans | 3 |
| Year Built | 1963 |
| Avg Daily Traffic | 63,024 (2024) |
| Truck Traffic | 6% |
| Lanes On Bridge | 3 |
| Lanes Under Bridge | 2 |
| Last Inspection | April 2024 |
| Inspection Frequency | Every 6 months |
| Owner | State Highway Agency |
| Historical Significance | Historical significance is not determined |
| Scour Critical | Not applicable |
| Structure Number | M170312XGDOTNBI |
Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."
A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.