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

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66 Cast-in-Place - Concrete poured within formwork on site to create a structural element in its final position. Castellated Girder - A steel beam fabricated by making a zig zag cut along its web, then welding the two sides together at their peaks. This creates a beam that has increased depth and, therefore, greater strength, but is not increased in weight. Catenary - Curve formed by a rope or chain hanging freely between two supports. The curved cables or chains used to support suspension bridges may be referred to as catenaries. Catwalks - Temporary foot bridges, used by bridge workers to spin the main cables (several feet above each catwalk), and to attach the suspender cables that connect the main cables to the deck. Centering - Temporary structure or falsework supporting an arch during construction. Chord - Either of the two principal members of a truss extending from end to end, connected by web members. Closed Spandrel Deck Arch - One of the oldest and strongest types of bridges, the arch has been used in bridge building since the Roman era. An arch supports weight by compression on an axis or keystone. The axis or keystone transfers the stress of gravity (the traffic load) outward toward the base of the arch. Supports called abutments absorb the pressure and stop the ends of the bridge from spreading apart. Most arch bridges have vertical supports called spandrels that distribute the weight on the deck
67 to the arch below. The first arch bridges were built of stone but now are constructed of concrete or steel for greater strength and durability. Arch bridges are strong because the entire structure is under compression. Therefore, they must be built of materials that are strong under compression. Putting more weight on the arch actually compresses the material and makes the structure more rigid. Most arch bridges span between 200-800 feet. Column - A vertical, structural element, strong in compression. Column Cross Brace - Transverse brace between two main longitudinal members. Compression Member - An engineering term that describes a timber or other truss member that is subjected to squeezing or pushing. Also see tension member. Condition Ratings - According to the National Bridge Inspection Standards (NBIS), condition ratings are used to describe an existing bridge or culvert compared with its condition if it were new. The ratings are based on the materials, physical condition of the deck (riding surface), the superstructure (supports
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"TOIORROW'S ROADS TODAY" EXPRESSWAY
Page 3 and 4:
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
Page 13 and 14:
13 after 1965. Those developments h
Page 15 and 16: 15 Figure 1: US 40 over the Patapsc
Page 17 and 18: 17 State Struggles The SRC also pro
Page 19 and 20: 19 As the SRC finalized the bridges
Page 21 and 22: 21 This central shore location was
Page 23 and 24: 23 William Preston Lane, Jr. and th
Page 25 and 26: 25 The BPR and National Park Servic
Page 27 and 28: 27 project. The highway bonds sold
Page 29 and 30: 29 highways that connected county s
Page 31 and 32: 31 Figure 10: I-695 at Dulaney Vall
Page 33 and 34: 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: 65 Bridge Condition Ratings - Throu
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 and 86: 85 Swing Bridge - A movable deck br
Page 87 and 88: 87 Unit Stress - The stress per uni
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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