Note 56 — PART I SPECIFICATIONS FOR STREET ROADWAY PAVEMENTS (continued 2)

Wherever an old pavement or macadam road can be utilized it makes an excellent foundation for a pavement of this kind, provided it is not in too dilapidated a condition, extends from curb to curb, and its surface conforms near enough to the desired street surface so that the necessary changes and repairs will not be too expensive. Where the new pavement is expected to carry quite a heavy travel it is not advisable to use plain crushed stone for filling depressions and leveling up the surface. It is difficult, even where proper care is used, to make such patches of broken stone as firm and strong as the adjoining old pavement, which is a necessary condition to secure satisfactory results; for if the masses of broken stone yield under travel, slight depressions will form over them in the bituminous surface, which will in time become holes requiring repairs. The 1:4:9 concrete specified for this work is not very much more expensive than plain broken stone, it will not shift or break up under travel, and will in the end prove a better investment.