United States Bureau of Public Roads

Engineers who are associated with trenching in public thoroughfares have been striving for many years to find better construction methods and procedures for backfilling these trenches. We cannot expect the public to tolerate detrimental settlement if it can be avoided with a reasonable expenditure of funds. In this study the presently used procedures of backfilling and compaction were observed. It was found that these procedures can definitely be improved. The major conclusions which can be drawn from the study are listed below. The layered system is the most reliable compaction procedure for limiting settlement to a minimum. With one compactor type, the Hydra-Hammer, the entire trench backfill can be compacted in one lift irrespective of soil type or traffic volume on the street. Adequate stability, to prevent detrimental settlement, can be attained with many compactor types if the lift height is adjusted to soil type and condition, and the trench loading conditions. All vibratory type trench compactors should be used strictly on the granular soils and the lift height must be chosen with respect to the particular compactor and the traffic volume. The Pneumatic Button Head compactor can effectively compact all soil types in lifts up to 0.5 feet in thickness. The Plate Tampers are excellent compactors for all soil types and they are capable of compacting soil lifts between 1.0 and 1.5 feet depending upon the traffic load. Heavy construction equipment should be used to compact only the upper lift in a trench and this lift should be restricted to the range of 1.0 to 2.5 feet in thickness depending upon the soil type and the traffic load. Further research under more controlled field conditions is planned for 1963.

This report discusses the effects of Interstate 94 bypassing the small towns in Pine County, using Hinckley, Minnesota as an example.

This report is a continuation of the 1960 study.

This report studies the effect of a highway change in Faribault, Minnesota. In 1955, Highway 65 was rerouted, meaning that cars on the road did not travel through Faribault's Central Business District.

The Critical Feature Survey was undertaken for the study of trunk highway needs and for the determination of practical road capacities. The Critical Feature Survey was conducted on all rural 2-lane sections of the trunk highway system. The data collected relates to sight distance, gradients, curves, and superelevations of curves. Data were not taken on the so-called institutional highways or on portions of the trunk highway system under construction.

The final report in a series of memorandum reports dealing with the Grand Forks-East Grand Forks Urban Area Transportation Study. Volume Six sums up the previous five volumes and lays out the plan for street improvements in the Grand Forks-East Grand Forks urban area based on the projected traffic in 1990.

The fifth in a series of memorandum reports dealing with the Grand Forks-East Grand Forks Urban Area Transportation Study. Volume Five lays out the goals and standards that the data in the previous volumes will be used for.

The fourth in a series of memorandum reports dealing with the Grand Forks-East Grand Forks Urban Area Transportation Study. Volume 4 relates to population characteristics in 1965.

The third in a series of memorandum reports dealing with the Grand Forks-East Grand Forks Urban Area Transportation Study. Volume 3 presents the results of the 1965 traffic survey.

The second in a series of memorandum reports dealing with the Grand Forks-East Grand Forks Urban Area Transportation Study. Volume Two with land use and zoning in 1965.