Bridge Information Model Standardization

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This Volume of the Report describes the modeling of specific components of bridges to the level of detail as conveyed on design contract plans, using two real-world case studies. Information contained within accompanying construction specifications (special provisions) is not captured as part of this scope; as such information is primarily textual, it may be incorporated by reference. Information contained in shop drawings is considered to be part of a different exchange and is not covered here. Three candidate schemas are applied in this effort to identify methodologies that would be valuable in a national bridge information modeling standard.

To ensure that details are captured that reflect common usage and reflect the level of information presented in design plans, two specific case study bridges were chosen for illustration deemed to be representative of highway bridges in the U.S., yet containing certain complexities that stretch the limits of the proposed information model.

The first bridge evaluated is Pennsylvania Turnpike Bridge MF-145 - Ramp 1195N over SR 51. This bridge follows a horizontal alignment consisting of circular and straight sections at a constant vertical slope, with varying super-elevation and varying cross-section. It is a 3-span continuous curved steel bridge with spans of 130’-180’-130’. It consists of steel I-girder framing, with reinforced concrete abutments, piers, and decking.

The second bridge evaluated is the Van White Memorial Overpass in Minneapolis, MN. This bridge follows a horizontal alignment consisting of circular and straight sections with a parabolic vertical curve, with varying super-elevation and constant cross section. It consists of a reinforced concrete box girder, abutments, and piers. As this bridge is situated in an urban area, it consists of decorative railings, walkways, and lighting, and makes use of geometry consisting of curved surfaces that cannot be described by polygons alone but requires B-Spline surfaces and Constructive Solid Geometry (CSG).

While it would certainly be preferable to model additional bridges, for this exercise it was deemed critical to first go through the process of modeling a limited set of specific bridges in the same detail as described in design plans before attempting to accommodate additional bridges at a lower level of detail. As with any such modeling effort, the Pareto principle applies, where the last 20% takes 80% of the time: the initial layout of the bridge deck, girders, and piers ended up being rather trivial (i.e. several days effort) compared to capturing the more detailed aspects found in the plans such as rebar, architectural railings, electrical (i.e. multiple weeks effort).

There are various other scenarios that may be encountered on other bridges which are not captured by this specific bridge, such as diverging roadways and interchanges.

Details are provided indicating how each component was modeled in the schemas evaluated. For such detail, familiarity with the schemas as described in Volume II may help in understanding.

Figure 1 illustrates a 3D rendering of the sample Penn Turnpike steel bridge. Figure 2 shows the first page of the plans, representing the overall alignment and positioning of major components. 
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Bridge Information Model Standardization
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