FIGURE 1.-A modern nuclear moisture-density gage developed jointly by the Ohio State University and the Ohio Department of Highways.

Infrared spectroscopy. Our Physical Research Division on its own or in cooperation with State highway departments has successfully conducted research in spectroscopy in the analysis and fingerprinting of complex road materials such as paints, asphalts and their components, and mineral and organic admixtures for concrete. In addition, it has a record of further accomplishments. It has produced the thin film overweathering test now being used as a quality control for paving asphalt. It has established a spectral identification or "fingerprint" file on chemical composition of service-proved concrete additives to reduce testing time for highway laboratories.

These are a few of the efforts that are being made to secure improved materials and the best use of all materials in the highway program. We feel that progress has been made toward these objectives.

Improvements in basic equipment components

Road equipment, methods, and materials used by the contractors and engineers on the jobsite have many hours and dollars of research and development support off the jobsite. These are being put to good use.

An important factor in efficient highway production is the minimizing of equipment "downtime" and in effectively utilizing manpower in material processing by reducing operator fatigue. Many of the new equipment models feature such improvement to basic com

ponents. These improved features are common to numerous construction units.

There has been a substantial reduction in the weight of diesel power units by the use of alloys and more compact designs; there is also a corresponding increase in the available horsepower per pound of engine. This trend has resulted in a desirable lowering of the center of gravity for many machines. Turbochargers and aftercoolers are provided in many applications for increased horsepower and efficiency. Engine accessories and particularly the air cleaners and oil filters have been improved to provide greater operating efficiency and prolonged engine life. All of these developments mean more durable equipment, less downtime, and lower operating costs for the contractor. In addition, the encourage the development and use of new and improved materials.

The torque converter drive has provided a wider range of tractive effort for varying load conditions. When used with the automatic or power-shift transmission, work output can be increased by 25 percent in some construction activities.

Other metallurgical advances in overall machine design include lighter frames or chassis with high tensile steel and vastly improved abrasive-resistant members which are in contact with soil and other materials.

Automatic controls. Many operating adjustments which were formerly performed manually are now activated hydraulically or electrically with fingertip controls. Automatic controls which assure the desired performance without human assistance have been built into many items of equipment. Comfort, safety, and convenience to the operator have not been overlooked in new equipment designs. Operator fatigue from shifting gears and clutching has been largely eliminated. All of these foster better results in material processing operations.

The tire manufacturing industry has also helped to decrease equipment downtime by providing major tire improvements for wheel-type construction machinery.

Improvements in petroleum products.-The petroleum industry has also made major contributions to machine operating efficiency by improvements in fuel, oil, and lubricants. The need for dozens of different grades and kinds of lubricants for various moving parts has been eliminated; maintenance problems for the contractor have been reduced; and the economic life of the machines has been greatly increased. These and other achievements of component manufacturers all help out the equipment industry to provide efficient and well-balanced machinery for the highway contractor.

Advanced lubrication systems. Improvements in lubricating systems are not confined to the modern motor vehicle. For example, the system for lubricating crawler parts has been developed to such an extent that "once in a lifetime" lubrication now takes place of that which was formerly required on a daily basis.

With this background on improved equipment components it is clear that, more often that not, they involve the development and use of new and improved materials.

SUPPLEMENTAL DATA RELATIVE TO THE USE OF SPECIFIC MATERIALS FOR HIGHWAYS

We have looked at general trends and progress pertinent to the current use of materials in the road program. More detailed information regarding the use of specific materials and the processes involved in their handling, treatment, and placement in highway construction, maintenance, or operation may be helpful. The following sections of this report contain this type of information.

9

NATURAL SOILS AND ROCK AS HIGHWAY MATERIALS

Earthworks-Scope, costs

The greatest volume and by far the least expensive material which goes into the formation of a highway are the natural soil and rock placed in embankments. It is estimated that approximately 2.4 billion cubic yards of common excavation will be placed on all highway systems during 1962.

For 1922, the average bid price, in terms of 1957-59 dollars, for common excavation on Federal-aid highway construction was $0.40 per cubic yard. Thirty-nine years later in 1961, the bid price was about the same or $0.41 per cubic yard. During this entire period, the 1922 unit price was exceeded only eight times. It was equal or less than the 1922 bid price for 31 years. Since other highway cost elements have risen as much as threefold during this 39-year period, this stabilization of earthwork prices can largely be attributed to the continuous improvement in earthmoving equipment and the parallel improvement in earthmoving techniques on the part of the highway contractor. Another contributing factor is the free hand the contractor has in selecting the equipment he uses it lends encouragement to the development of mass production methods.

If the cost of moving, placing, and processing earth had risen as other highway costs have, we would not be able to undertake the highway program as it is today. The fact that we can and are building roads with wider rights-of-way, flatter grades, easier curves, longer sight distances, and other features which add to the comfort, safety, and convenience of motorists is a tribute to the improvements that have been made in earthmoving equipment and techniques. Earthmoving equipment

Recent improvements in earthmoving equipment such as crawler and wheeled-type tractors feature both increased capacity and operating speeds. Large rear-mounted tractor rippers are available which further expedite highway grading operations. Disintegrated rock, shales, and other materials which formerly required blasting can now be ripped for easier and more economical handling and processing. The off-highway hauling units, including large rear dump trucks and modern hauling scrapers with pneumatic-tired tractors exemply a combination of both speed and capacity.

If solid rock excavation is involved, a number of new portable air compressor models, with greater capacity, are available. Improved pneumatic drills have also been developed including wheel and crawler mounted rigs which are capable of drilling 4- and 6-inch blast holes to accommodate some of the new type explosives.