TOMORROW'S ROADS TODAY - Maryland State Highway ...

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86 In a deck configuration, traffic travels on top of the main structure; in a pony configuration traffic travels between parallel superstructures, which are not cross-braced at the top; in a through configuration, traffic travels through the superstructure (usually a truss), which is cross-braced above and below traffic. Trussed Arch - A metal arch bridge that features a curved truss. Two-Hinged Arch and Three-Hinged Arches - Arches use a curved structure that provides a high resistance to bending forces. Unlike girder and truss bridges, both ends of an arch are fixed in the horizontal direction (i.e., no horizontal movement is allowed in the bearing). Thus when a load is placed on the bridge (e.g., a car passes over it) horizontal forces occur in the bearings of the arch. These horizontal forces are unique to the arch and as a result arches can only be used where the ground or foundation is solid and stable. Like the truss, the roadway may pass over or through an arch or in some cases both Structurally, there are four basic arch types: hinge-less, two-hinged, three hinged, and tied arches. The three-hinged arch adds an additional hinge at the top or crown of the arch. The three-hinged arch suffers very little if there is movement in either foundation (due to earthquakes, sinking, etc.) However, the three-hinged arch experiences much more deflection and the hinges are complex and can be difficult to fabricate. The three-hinged arch is rarely used anymore. U-Bolt - A bar bent in the shape of the letter "U" and fitted with threads and nuts at its ends. Ultimate Strength - The highest stress that a material can withstand before breaking. Ultrasonic Testing - Nondestructive testing of a material's integrity using sound waves. Underpass - The lowest feature of a grade separated crossing. Uniform Load - A constant load across a member.
87 Unit Stress - The stress per unit of surface or cross-sectional area. Uplift - A negative reaction or a force tending to lift a beam, truss, pile, or any other bridge element upwards. Upper Chord - Top chord of a truss. Upstream Face - The side of a bridge that is against the water. Vault - An enclosing structure formed by building a series of adjacent arches. Vertical Curve - A sag or crest in the profile of a roadway. Vertical Lift Bridge - A movable deck bridge in which the deck may be raised vertically by synchronized machinery at each end. Viaduct - A long, multi-span structure, especially one constructed of concrete. More commonly used in relation to structures carrying motor vehicles. Trestle is the term for a similar structure when used in relation to railroads. Void - An empty or unfilled space in concrete. Voussoir - Any one of the wedge shaped block used to form an arch. Voussoir Arch - An arrangement of wedge shaped blocks set to form an arched bridge. Waterway - The available width for the passage of water beneath a bridge. Wearing Surface - The topmost layer of material applied upon a roadway to receive the traffic loads and to resist the resulting disintegrating action; also known as wearing course. Web - The system of members connecting the top and bottom chords of a truss. Or the vertical portion of an I-beam or girder. Web Members - The intermediate members of a truss, not including the end posts, usually vertical or inclined. Web Plate - The plate forming the web element of a plate girder, built-up beam or column. Web Stiffener - A small member welded to a beam web to prevent buckling of the web. Weephole - A hole in a concrete retaining wall to provide drainage of the water in the retained soil. Weigh in Motion (WIM) - Equipment that measures the weight of moving trucks. Is used by state highway agencies for monitoring pavement loadings. Weld - A joint between pieces of metal at faces that have been made plastic by heat or pressure.
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"TOIORROW'S ROADS TODAY" EXPRESSWAY
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3 SHA identified 286 highway bridge
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5 Table of Figures Figure 1: US 40
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7 Until 1941, Maryland did not have
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9 plate metal girder bridges. The n
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11 Epigraph “Tomorrow’s Roads T
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13 after 1965. Those developments h
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15 Figure 1: US 40 over the Patapsc
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17 State Struggles The SRC also pro
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19 As the SRC finalized the bridges
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21 This central shore location was
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23 William Preston Lane, Jr. and th
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25 The BPR and National Park Servic
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27 project. The highway bonds sold
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29 highways that connected county s
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31 Figure 10: I-695 at Dulaney Vall
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33 Figure 12: Atomic Energy Commiss
Page 35 and 36: 35 Federal Aid Highway Act of 1956
Page 37 and 38: 37 Maryland continued to apply for
Page 39 and 40: 39 SRC expanded the road to a four-
Page 41 and 42: 41 completion of the two interchang
Page 43 and 44: 43 Figure 17: Governor Elbert N. Ca
Page 45 and 46: 45 Each of these bridges provides u
Page 47 and 48: 47 Bibliography American Associatio
Page 49 and 50: 49 Maryland-National Capital Park a
Page 51 and 52: 51 ____________, Report of the Stat
Page 53 and 54: 53 Appendix A: Results of Field Inv
Page 55 and 56: 55 Steel Deck Truss - similar to St
Page 57 and 58: 57 Concrete Encased Steel Beam, SHA
Page 59 and 60: 59 or Bethlehem Steel types would b
Page 61 and 62: 61 Eligible Bridges The following b
Page 63 and 64: 63 to carry boats. Sometimes carrie
Page 65 and 66: 65 Bridge Condition Ratings - Throu
Page 67 and 68: 67 to the arch below. The first arc
Page 69 and 70: 69 Deck Bridge - A bridge in which
Page 71 and 72: 71 Embankment - Angled grading of t
Page 73 and 74: 73 Girder - A horizontal structure
Page 75 and 76: 75 Headwall - The device placed at
Page 77 and 78: 77 Lag - Crosspieces used to connec
Page 79 and 80: 79 Parapet - A low wall along the o
Page 81 and 82: 81 of multiple members of a truss.
Page 83 and 84: 83 Spandrel - The roughly triangula
Page 85: 85 Swing Bridge - A movable deck br
Page 89 and 90: Appendix D: SHA Bridges Included in
Page 91 and 92: 91 Eligibility Description Bridge N
Page 101 and 102: 101 Eligibility Description Bridge
Page 103: Appendix E: Resume Anne E. Bruder i
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