The large volume of airfield pavement construction in the past 6 or 7 years has led to a number of important changes in construction equipment and techniques- some of which, at least, are already finding their way into general pavement practice. High take-off ant landing speeds for example, have required a severe tightening of specification surface tolerances and grade control in order to provide the plane surface necessary for safe operation. The resulting new grade control requirements have demanded more accurate form setting and ta closer straightedge testing of forms and surface. This rolling straightedge, or hi-lo tester as it is called, can accurately detect deviations of as little as one-eighth of and inch to 12 feet on either forms or finished concrete. This is the maximum permitted in the longitudinal direction on runways and taxiways for the Air Force today. New finishing equipment is being built to assist contractors to meet these stricter surface tolerances and also to combine the work of the transverse finishing machine and longitudinal float to permit the elimination of one piece of equipment from the paving train. The stricter surface tolerances have required more careful use of scraping straightedges. One new machine for cutting off high spots has a 16 and one-half of and inch wide head consisting of a series of diamond saw blades. The head can be set on the 12 foot wheel base machine so that it cuts all high spots to meet specifications. Two new modifications of sawed joints have been developed in an effort to reduce the cost of sawing in hard aggregates and permit earlier sawing to insure positive crack control. One requires using a special machine which vibrates a transverse bar made of perforated metal into the concrete surface at the exact joint location to displace the coarse aggregate. The second modification involves the insertion of an asphalt-impregnated felt board of the proper dimensions at the joint location.