48 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE. 
result when the mixing is resumed. On this account the order and 
progress of the work should ordinarily be planned with the primary 
view to keeping the mixer going full time every working day that 
the weather will permit. This means that ample provision should be 
made for completing the drainage structures, the grading, and the 
preparation of the subgrade well ahead of the mixer. Provision 
should also be made for supplying the mixer with all necessary ma- 
terials. Where the materials are obtained by rail shipment, and it is 
expected that these shipments will be rather irregular, sufficient ma- 
terial for at least J to 1 mile of road should be stored on the subgrade 
or at the unloading yard before the mixing is started. This material 
can be stored with a comparatively small working force, so that an 
interruption of their work will not be as costly as a delay to the full 
hauling and mixing force. 
The small drainage structures should preferably be completed in 
advance of the grading in order to obviate the necessity of moving 
embankment material the second time. They should always be com- 
pleted in advance of the pavement. It is not economical to leave out 
a section of the pavement over a small cuh 7 ert, and this practice 
should not be permitted. The extra expense involved in going back 
and putting in a section of this kind after the pavement has pro- 
gressed a considerable distance ahead is usually considerable and is 
often underestimated. This method of doing the work also involves 
a delay in opening the road, adds two extra joints, and usually re- 
sults in securing an improperly cured pavement over the culvert. 
Organizing a force of laborers to operate a paving mixer efficiently 
requires considerable skill in handling men. The best results are 
generally obtained when a mixer is fully manned and each laborer 
is assigned a definite work to perform. 
Diagrams showing organization and plant layout for a number of 
typical methods employed in concrete pavement construction are 
given in Figures 11 to 15, inclusive. These organizations and lay- 
outs have been used in actual construction work and have proved 
to be.ven' satisfactory. 
EQUIPMENT. 
Any discussion of equipment must necessarily be more or less gen- 
eral, because the same equipment is not always best suited for each 
particular piece of work. Each project possesses certain character- 
istics which determine the kind of equipment best adapted for han- 
dling it. A contractor may either wait until he has secured a con- 
tract before he decides on the type of equipment to purchase or he 
may purchase the equipment which he feels will give him the best 
satisfaction and only bid on work for which this equipment is suited. 
