The objective of Chapter 10 is to present overview examples of the use of the principles

presented in this manual in the design of highway encroachments and crossings in the river

environment. A three-level design procedure is emphasized in these designs. The designs

use the geomorphic, hydrologic, hydraulic, and river mechanics principles described in this

manual to design safe and economical crossings that protect, maintain and restore the river

environment.

Three examples are given to illustrate the application of the principles, methods, and

concepts given in this manual. In the examples, the designs are determined by well-

established numerical procedures; however, they also depend heavily on the judgment of the

engineer.

Chapter 11 contains an alphabetical listing of the references cited throughout the document.

The appendices present a discussion of the metric (SI) system (Appendix A), analysis of

additional sediment transport relationships (Appendix B), and an Index (Appendix C).

This manual uses dual units (SI metric and English). In Appendix A, the metric (SI) unit of

measurement is explained. The conversion factors, physical properties of water in SI system

of units, sediment particle size grade scale, and some common equivalent hydraulic units

are also given. This edition uses for the unit of length the meter (m) or foot (ft); of mass the

kilogram (kg) or slug; of weight/force the newton (N) or pound (lb); of pressure the Pascal

2

2

(Pa, N/m ) or (lb/ft ); and of temperature the degree centigrade (C) or Fahrenheit (F). The

unit of time is the same in SI as in English system (seconds, s). Sediment particle size is

given in millimeters (mm), but in calculations the decimal equivalent of millimeters in meters

is used (1 mm = 0.001 m) or for the English system feet (ft). The value of some hydraulic

engineering terms used in the text in SI units and their equivalent English units are given in

Table 1.1.

Table 1.1. Commonly Used Engineering Terms in SI and English Units.

Term

SI Units

English Units

Length

1m

3.28 ft

3

3

Volume

1m

35.31 ft

3

3

Discharge

1 m /s

35.31 ft /s

2

2

Acceleration of Gravity

9.81 m/s

32.2 ft/s

3

3

Unit Weight of Water

9800 N/m

62.4 lb/ft

3

3

Density of Water

1000 kg/m

1.94 slugs/ft

3

3

Density of Quartz

2647 kg/m

5.14 slugs/ft

Specific Gravity of Quartz

2.65

2.65

Specific Gravity of Water

1

1

Temperature

C = 5/9 (F - 32)

F

1.21

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