Ll 
rather than from contours on maps. The profile and cross sections are uti- 
lized in fitting the highway to the topography and land use vertically, cross 
sectionally, qualitatively, and quantitatively. This is done by employing 
electronic methods of computation, examining the initial design, and making 
appropriate adjustments on the basis of qualitative information, physical fea- 
tures, quantitative data, rights-of-way, traffic Services, and likelihood, in 
the future, of road failures and interruption of traffic services. 
The initial design is revised by repeating, as necessary, the preceding 
procedure to attain, insofar as feasible, every possible, practicable, and 
economical improvement in the design. Mathematical descriptions are modified, 
in appropriate terms and details, to include all revisions made in the aline- 
ment, profile gradients, and rights-of-way since completion of the initial 
phase of this indirect procedure. 
The result of this engineering design is a set of detailed construction 
plans to guide the appraisers and negotiators in procuring needed rights-of- 
way, the engineers in staking on the ground the highway, highway structures, 
and rights-of-way, and also to guide construction forces in constructing the 
highway. 
APPLICATIONS IN THE LOCATION SURVEY 
When aerial surveys are employed throughout the preceding stages, the 
location survey is the first stage, for most highways, in which detailed stak- 
ing on the ground is essential. All work is governed by the preceding accom- 
plishments. Some previous staking, however, is always required in conjunc- 
tion with ground control surveys for each stage in which mapping is done. Con- 
trol points established by such surveys and preserved in position by station 
markers serve as origin and checking points of closure in all surveying in this 
stage. Initial line staking, done previously for clearing purposes in certain 
phases of the reconnaissance survey of alternate routes and in the indirect 
procedure of preliminary survey and design, serves as positioning control for 
line staking in this stage. The objective in the location survey is a highway 
staked on the ground in readiness for construction. 
Following completion of the preliminary survey in the direct procedure, 
the first work on the ground in the location survey begins with centerline stak- 
ing. Following completion of the preliminary survey by the indirect procedure, 
the first ground work begins with staking revisions to the initially designed 
and staked centerline--revisions that were made during the more detailed design 
after obtaining the larger scale photography and completing planimetric mapping 
and measurement of profile and cross sections in the second phase of the indi- 
rect procedure. If revisions were not made, centerline staking is limited to 
replacing missing stakes and references, and to correcting distances found to 
be in error while compiling the second phase maps. 
For staking the centerline, the plane coordinates of each station marker 
and centerline point are utilized to compute the distance and plane coordinate 
grid bearing to the nearest alinement point such as P.I., curvature point, or 
P.0.T., from each convenient station marker. The deviation from true north of 
the plane coordinate grid on the map and of the bearing of the tie between each 
basic control point and the nearest alinement point is also determined. 
Utilizing these data, the centerline of the highway is staked on the ground 
and its profile is measured. Bench marks and all of the references for points 
on the centerline are placed where they will not be disturbed by the construc- 
tion forces and by the normal use of the land. The right-of-way lines are also 
staked. 
Completion of the location survey marks the end of preliminary engineering, 
although nothing is "final" until the highway is constructed.