use a pair of straddle hubs (commonly called STRADDLERS), as shown in figure 13-25. Here the point was to be located at an angle of 3433 from station 2 + 00 and at an angle of 5121 from station 3 + 00. The transit was set up at station 2 + 00, sighted on station 3 + 00, and an angle of 3433 was turned to the right. On this line of sight, a pair of straddle hubs was driven, one on either side of the estimated point of inter-section of the tie lines. A cord was stretched between the straddlers.

The transit was then shifted to station 3 + 00, sighted on station 2 + 00, and an angle of 5121 was turned to the left. A hub was driven at the point where this line of sight intercepted the cord between the straddlers.

Setting Points When Given an Angle from One Station and the Distance from Another

To set a point with a given angle from one station and the distance from another, you would find it best to determine the direction of the distance line by triangle solution. In figure 13-26,

point B is to be located 100.0 ft from station A and at an angle of 5000 from station C. In this example, you can determine the size of the angle at A by first determining the size of angle B, then subtracting the sum of angles B and C from 180. The solution for angle B is as follows:

Angle B then measures, to the nearest minute, 8447. Therefore, angle A measures 

Set up a transit at A, sight on C, and turn 4513 to the left. Then, you set B by measuring off 100.0 ft on this line of sight. As a check, you set up the transit at C, sight on A, turn 5000 to the right, and make sure this line of sight intercepts the marker at B.