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Maryland

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Havre de Grace vicinity

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Post Road Bridge, State Route 7-A, Havre de Grace, Harford County, MD



B&W Photos


Data Pages


Photo Caption Pages


Item Title


Location
State Route 7-A, Havre de Grace vicinity, MD

Find maps of Havre de Grace, MD


Created/Published
Documentation compiled after 1968.

Notes
Survey number HAER MD-44
Building/structure dates: 1905 initial construction
Building/structure dates: 1952 subsequent work
Building/structure dates: 1982 demolished
Significance: The bridge, a subdivided Pratt through truss commonly known as a Baltimore truss with substruts and subties, is an example of an early truss form developed for use on long spans. The bridge was fabricated by the American Bridge Company in 1905 for the Maryland Division, P.B. & W. RR. of the Pennsylvania Railroad.

Subjects
Truss Bridges
Vehicular Bridges


Related Names
American Bridge Company


Collection
Historic American Engineering Record (Library of Congress)

Contents
Photograph caption(s): 
1. View looking southwest down AMTRAK mainline toward bridge.
2. View looking south toward bridge.
3. View looking east, down toward bridge.
4. Close-up view looking northeast at bridge along AMTRAK mainline.
5. Perspective view of the northwest side and southwest end elevations of the bridge.
6. Long range view of the southwest portal of the bridge.
7. Close view of the southwest portal of the bridge.
8. Long range view of the northeast portal of the bridge.
9. Close view of the northeast portal of the bridge.
10. Southeast elevation of the bridge.
11. General interior elevation viewed from midspan toward the northeast, showing the corrugated metal barriers on both sides and the asphalt deck.
12. Detail of west side of southwest portal showing the latticed diagonal brace and the hip vertical, pin-connected to the latticed inclined end post directly beneath the riveted connection with the portal bracing.
13. Detail of west side of southwest portal showing the latticed top chord rivet-connected to the latticed inclined end post and the portal strut; also shown is the webbed portal bracing and the top lateral bracing with the pin connection of the hip vertical and the diagonal.
14. Detail along the northwest side of the inside of the bridge, in the center of the second panel from the western bridge shoe; the view shows the latticed vertical, pin-connected with the latticed diagonal and the top and bottom counter braces. The vertical is constructed for compression above the pin and for tension below the pin.
15. Detail along the northwest side of the inside of the bridge, showing the latticed vertical post that separates the second from the third panel point on the southwest end; the latticed top strut is rivet-connected to the vertical post and the top strut.
16. Detail along the northwest side of the inside of the bridge, showing the pin connection in the center of the third panel from the western bridge shoe; again the vertical is constructed for compression above the pin and for tension below the pin.
17. Detail along the northwest side of the inside of the bridge showing the pin connection of the vertical in the center of the fourth panel (the centerline of the bridge) with the diagonals and the counter bracing.
20. Detail from below, of the northwest side of the bridge in the center of the first panel adjacent to the western bridge shoe; shown is the compound connection where the floor beam is rivet-connected to the vertical and then pin-connected to the bottom chords of the truss.
21. Detail of the east corner shoe where the latticed inclined end post is pin-connected to the bottom chord of the truss and the show that rests on the stone abutment.
22. General view of the underside of the bridge looking toward the northeast abutment.
23. American Bridge Company Drawing No. 1; End posts and top chords; dated 4-3-1905.
24. American Bridge Company Drawing No. 2; Posts; dated 4-10-1905.
25. American Bridge Company Drawing No. 3; Posts, diagonals, and middle struts; dated 4-7-1905.
26. American Bridge Company Drawing No. 4; Floor beams and stringers; dated 4-7-1905.
27. American Bridge Company Drawing No. 5; Top struts and portal struts; dated 4-7-1905.
28. American Bridge Company Drawing No. 6; Bottom laterals; dated 4-5-1905.
29. American Bridge Company Drawing No. 7; Shoes and bedplates; dated 4-6-1905.
30. American Bridge Company Drawing No. 8; Fences; dated 4-5-1905.
31. American Bridge Company Drawing No. 9; Top laterals and struts; dated 4-5-1905.
32. American Bridge Company Drawing No. El; Erection Diagram; dated 4-13-1905.
33. P.B. & W. Railroad Drawing of Truss Members and Stresses; dated 3-13-1905.


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