Filtering by
- All Subjects: Phnom Penh (Cambodia)
- All Subjects: Desert conservation
- All Subjects: Agriculture
- All Subjects: Legislation
In the mid‐1990s, the Arizona Department of Transportation initiated the Maintenance Cost Effectiveness study (SPR 371) with the development of plans and an experiment design to evaluate the effectiveness of a variety of asphalt pavement maintenance treatments. During 1999 and 2001, ADOT oversaw the construction of hundreds of experimental sections throughout the state under the Phase I, Wearing Course Experiment (nine treatments and 82 sections at three sites), and the Phase II, Preventive Maintenance Experiment (24 treatments and 137 sections at four sites). Work continued in 2006 and 2007 under the Evaluation of Maintenance Strategies study (SPR 628) for ADOT with a yearlong program of pavement performance monitoring involving manual pavement distress surveys and automated skid, friction, and surface texture measurements at all the experimental sites. The project culminated with a detailed analysis of key pavement performance data to compare the performance of the individual treatments and determine their overall effectiveness. This report documents the independent findings of both the Phase I and II experiments.
Speech by Carl T. Hayden offering a motion to authorize a road an trail construction program in Grand Canyon National Park "to make these natural wonders accessible to the American people." The speech appears in the Congressional Record, 68th Congress, First Session.
Letter from Alexander Vogelsang to Homer P. Snyder regarding land allocation for the Havasupai Tribe.
Amendments to the bill establishing the Grand Canyon a National Monument. Circa 1908.
Letter from C. H. Gensler, Havasupai Agency to Carl Hayden regarding boundary lines.
Letter from Carl T. Hayden to C. H. Gensler, Havasupai Indian Reservation, regarding Hualapai and Cataract Canyons geography.
Letter from W. W. Bass to Carl Hayden regarding the right to his property.
Letter from George Otis Smith, U.S. Geological Survey to Carl Hayden regarding asbestos mining prospects in the Grand Canyon.
Letter from Carl Hayden to George Otis Smith asking his advice regarding the mining of asbestos deposits in the Grand Canyon.
Letter from George Otis Smith to Carl Hayden regarding mining rights in the Grand Canyon.