Structures Design Guidelines | July 2004
1 - General Requirements |

## 1.1 General

This Chapter clarifies, supplements, and contains deviations from the information in LRFD Sections [2], [5], and [6]. These combined requirements establish material selection criteria for durability to meet the 75-year design life requirement established by the Department.

### 1.1.1 Design Review

Category 1 structures will be reviewed by the DSDE and Category 2 structures will be reviewed by the SSDE. See the PPM Chapter 26.

### 1.1.2 Substructure and Superstructure Definitions

See the substructure and superstructure definitions in the FDOT Standard Specifications for Road and Bridge Construction, Section 1-3 Definitions, and note the following:

A. Box culverts, retaining wall systems (including MSE walls), sound barriers on structures and bulkheads are substructures.

B. Approach slabs are superstructure; however, Class II Concrete (Bridge Deck) will be used for all environmental classifications.

### 1.1.3 Vertical Clearances

A. The vertical clearance of bridges over water is the minimum distance between the underside of the superstructure and the normal high water (NHW) for navigable water crossings or the mean high water (MHW) for coastal crossings. When applicable, vertical clearance is measured at the inside face of the fender system.

B. The vertical clearance for grade separations over roads or railroads is the minimum distance between the underside of the superstructure and road or railroad.

### 1.1.4 Bridge Height Classifications

FDOT classifications of bridges over water are based on the following vertical clearances:

A. Low Level - less than 20 feet.

B. Medium Level - 20 feet or greater but less than 45 feet.

C. High Level - 45 feet or greater.