From Engineering Surveying, Sixth Edition

10.3 COMPOUND AND REVERSE CURVES

Although equations are available which solve compound curves (Figure 10.14) and reverse curves (Figure 10.15), they are difficult to remember so it is best to treat the problem as two simple curves with a common tangent point t.


Figure 10.14: Compound curve

Figure 10.15: Reverse curve

In the case of the compound curve, the total tangent lengths T 1 I and T 2 I are found as follows:

R 1 tan ? 1/2 = T 1 t 1 = t 1 t

and

R 2 tan ? 2/2 = T 2 t 2 = t 2 t, as t 1 t 2 = t 1 t + t 2 t

then triangle t 1 It 2 may be solved for lengths t 1 I and t 2 I which, if added to the known lengths T 1 t 1 and T 2 t 2 respectively, give the total tangent lengths.

In setting out this curve, the first curve R 1 is set out in the usual way to point t. The theodolite is moved to t and backsighted to T 1, with the horizontal circle reading (180 - ? 1/2). Set the instrument to read zero and it will then be pointing to t 2. Thus the instrument is now oriented and reading zero, prior to setting out curve R 2.

In...

Copyright W. Schofield and M. Breach 2007 under license agreement with Books24x7

Products & Services
Polarimeters
Polarimeters determine the amount of polarization of light.
Spring Washers
Spring washers, sometimes called disc springs, lend their mechanical capabilities to the unique profile of the material: the irregularities of the washer compress with a proportionate resistance to return to their predeflected shape. Spring washers are employed in applications where assemblies need a part to take up play, maintain assembly tension, compensate for expansion or contraction in materials, or to absorb intermittent shock loads and provide a controlled reaction under dynamic loads.
Industrial Valves
Industrial valves are classified in many different ways. They can be distinguished by material of construction, media handled, and/or application.

Topics of Interest

10.4 SHORT AND/OR SMALL-RADIUS CURVES Short and/or small-radius curves such as for kerb lines, bay windows or for the construction of large templates may be set out by the following methods. 10.4.1...

10.6 SETTING-OUT DATA Figure 10.28 indicates the usual situation of two straights projected forward to intersect at I with a clothoid transition curve commencing from tangent point T 1 and joining...

10.1 CIRCULAR CURVES Two straights, D 1 T 1 and D 2 T 2 in Figure 10.1, are connected by a circular curve of radius R: The straights when projected forward, meet at I: the intersection point. The...

10.9 THE OSCULATING CIRCLE Figure 10.31 illustrates a transition curve T 1PE. Through P; where the transition radius is r, a simple curve of the same radius is drawn and called the osculating circle.

Robert W. Stokes Highway Curves a. Simple (Circular) Horizontal Curves The location of highway centerlines is initially laid out as a series of straight lines (tangent sections). These tangents are...