lans all information
necessary to enable the construction to be carried out according to
the intentions of the engineer, that all parts of the work fit
together, that the culverts are of the proper size and located at the
proper places, ditches drain properly, grades are reduced to the
predetermined rate, that excavated material is utilized and that an
exact record of the work done is retained. Plans are indispensable to
economical road construction and the preparation of the plans is the
work of the expert in road design, that is, the highway engineer.

=Problem of Design.=--The problem of road design is to prepare plans
for a road improvement with the various details so correlated as to
insure in the road constructed in accordance therewith the maximum of
safety, convenience and economy to the users thereof. The degree to
which the design will be effective will depend to a considerable
extent upon the financial limitations imposed upon the engineer, but
skill and effort on the plans will do a great deal to offset financial
handicap and no pains should be spared in the preparation of the
plans. Moreover, the plans must afford all of the information needed
by the contractor in preparing a bid for the work.

=Preliminary Investigation.=--The first step in road improvement is to
secure an adequate idea of the existing conditions on the road or
roads involved. The detail to which this information need go will
depend entirely upon the purpose of the preliminary investigation, for
before a definite plan is prepared, it may be necessary to choose the
best from among several available routes. For this purpose, it is not
always necessary to make an actual instrument survey of the several
routes. A hasty reconnaissance will usually be sufficient. This is
made by walking or riding over the road and noting, in a suitable book
or upon prepared blanks, the information needed. The items of
information recorded will usually be as follows: distances, grades,
type of soil on the road and nature of existing surface, character of
drainage, location of bridges and culverts and the type of each with
notes as to its condition, location of railway crossings and notes as
to type, location of intersecting roads, farm entrances, and all
similar features that have a bearing on the choice of routes. These
data can be obtained in a comparatively short time by a skilled
observer who may drive over the road in a motor car. Sometimes it may
be desir