Bridge Design Manual: Structure Type

Section 2: Structure Type

Superstructure

Selecting an appropriate superstructure type is a critical factor in the planning and design process. District design engineers, area engineers, or their consultants usually make the choice of superstructure type, as they prepare the preliminary bridge layouts.

The following figures illustrate the most common superstructure types currently used by TxDOT:

Figure 5-1: Cast-In-Place, Simple Slab Span
Figure 5-2: Cast-In-Place, Continuous Slab Unit
Figure 5-3: Cast-In-Place, Pan Form Spans
Figure 5-4: Prestressed - Precast, I-Beam Slab Span
Figure 5-5: Prestressed - Precast, Double Tee Beam Spans
Figure 5-6: Prestressed - Precast, TxDOT Box Beam Spans
Figure 5-7: Prestressed - Precast, Slab Beam Spans
Figure 5-8: Prestressed - Continuous Slab Units
Figure 5-9: Prestressed - Precast, U-Beam Spans
Figure 5-10: Segmental, Continuous Box Girder Units
Figure 5-11: Segmental, Simple Span Box Girder Units
Figure 5-12: Steel, I-Beam Units
Figure 5-13: Steel, Continuous Plate Girder Units
Figure 5-14: Steel, Continuous Trapezoidal Girder Units

The figures show the economical and practical span limits, and some advantages and disadvantages of each superstructure type.

In some cases the district may have a preference for certain structure types. If there is any doubt as to the proper design for the situation, district personnel should contact the bridge project development manager or the director of Bridge Design for assistance in determining structure type and span lengths.

Currently, over 30,000 bridges and bridge class culverts exist on the state highway system. The most common types of superstructure in use, and a quantity breakdown, are shown in "Types of Superstructure and Quantity Breakdown of On-System Bridges in Texas (FY 2000)" table to further aid in selecting a superstructure type.

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