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Cleveland Regional Geodetic Survey Provides Control for 450-Square Mile Area Professor of Civil Engineering, Case Institute of Technology, Cleveland, Ohio; THE CLEVELAND Regional Geodetic Survey is undoubtedly one of the most uniquely operated surveys ever attempted, largely because of the methods used in obtaining and maintaining the organization. The survey is sponsored by state, county, and city organizations which are varied in their political manifestations. Credit for conception of this sponsorship plan is due to Ernest J. Bohn, Director, Regional Association of Cleveland, and also at present Commissioner of City Planning, City of Cleveland. Although changes of administration have occurred during the course of the survey, each succeeding administration has continued to loyally support the project which ultimately will provide Cuyahoga County with accurate horizontal and vertical survey control. For the past 30 years, engineering organizations and societies in Greater Cleveland have discussed the desirability of an accurate, unified survey control in Cuyahoga County. Naturally, the deterrent had been the seemingly insurmountable obstacle of financing. The plan, which has incorporated in it the solution to the problem of financing, is simply this: Those public agencies which derive the greatest benefit from the results provide sponsorship in the form of personnel, equipment, supplies and materials, together with essential office space and equipment storage space. The financing therefore is borne jointly by a number of public agencies, thus making the survey possible. The survey began operations July 12, 1937. Later in the same year the necessary project proposal, to include the WPA as a sponsor, was drafted. The WPA organization provided: (1) Personnel in the lower employment brackets, (2) personnel to perform administrative work, and (3) the bulk of the supplies and materials. WPA withdrew its sponsorship on July 31, 1942. When completed, the Cleveland Regional Geodetic Survey will provide control for an area of approximately 450 sq miles, about one-sixth of it within the City of Cleveland. The built-up area (Cleveland and its suburbs) includes about 130 sq miles.
Specifications for Survey The specifications for the several orders of horizontal and vertical control, as well as the plane-table mapping, conform with those recommended in the ASCE Manual No. 10, "Technical Procedure for City Surveys." Slight modifications have been introduced where engineering economy was not affected. Triangulation reconnaissance in the urban area was facilitated by using the roofs of various buildings. Likewise in rural areas, roofs of buildings or barns were used where possible. The observing specifications conform to the instrument used. For about the first two years, a Kern 1-sec theodolite was on loan from the U.S. Coast and Geodetic Survey. Recommended specifications of the Coast Survey (Special Publication No. 120) were employed when using this instrument. In addition, a 2-sec Kern, a 1-sec Wild, and a 10-sec Gurley have been used in the observing program with a permissible 5-sec spread from the mean prior to rejection and reobservation. Six sets of the standard twelve repetitions for the 10-sec Gurley are required as the equivalent of the theodolite observing programs. Where the observing program failed to result in triangle closures commensurate with the specifications, reobserving was executed until assured direction values were obtained. There were instances where directions were reobserved seven times and properly meaned to provide the most probable result for each direction. As of January 1, 1948, a total of 927 directions had been observed 2,070 times for an average of 2.24 observations per direction. There are four Lake Survey triangulation stations in Cuyahoga County. Three are included in the new net; the fourth was recovered and occupied by the U.S. Coast and Geodetic Survey in 1943. One of these Lake Survey stations, "Warrensville," is employed as fix for the projection. Azimuth and position transfers are made from the triangulation stations to pairs of permanent ground monuments via quadrilateral or center point figures. As of January 1, 1948, a total of 1,477 transfer directions had been observed 2,758 times for an average of 1.87 observations per direction. The pairs of bronze-capped, precast concrete monuments interspersed throughout the county provide permanent transfer and traverse control stations. These monuments serve the surveying profession with starting coordinates and azimuths. The average distance between the two monuments in each pair is approximately 700 ft. The pairs are spaced approximately 0.6 mile apart in the urban area and 0.8 mile apart in the rural area. To date, 1,520 Cleveland Regional Geodetic Survey Official Monuments have been set, the majority in pairs. First-Order Levels The county was divided into 20 large circuits for the initial adjustment of first-order levels. These circuits averaged approximately 17 miles in periphery. They represented a total of 220 miles of levels run in the field. Wherever possible, the level lines and the traverse courses are along the same streets and roads. This arrangement has proved advantageous where the taping party has carelessly dropped a tape length, inasmuch as the stadia interval on the level observations offers an approximate check on the distance between two monuments. The average loop closure in the initial level least-squares adjustment was 0.025 ft with a maximum of 0.064 ft. These large level circuits were further subdivided by first-order level lines, usually into four smaller loops. Loops were also added to the periphery of the original net. A total of 93 of these smaller loops went into the final least squares adjustment. The average loop closure was 0.020 ft with a maximum of 0.063 ft. Second-Order Level Lines Next, these smaller loops were further subdivided by second-order level lines (levels run in one direction only), usually into four smaller loops. By this means level lines are provided on streets and roads at approximately one-mile intervals, north-south and east-west, throughout the county. The spacing is a little less than a mile in urban areas and a little greater than a mile in rural areas. In all, there are 583.91 miles if first-order levels plus 110.74 miles of reruns (19 percent), and 718.62 miles of second-order levels plus 75.83 miles of reruns (10.5 percent) for a total of 1,489.11 miles of levels to complete the vertical control. The city and county passed ordinances legislating the adoption of the new mean sea level datum in 1940. In all, there are approximately 3,000 monuments scattered throughout the 450 sq miles. It is not necessary to carry levels further than one-quarter miles on the main streets in urban areas, whereas on main roads in rural areas the maximum run is about one-half mile.
NEW EQUIPMENT designed for Cleveland Regional Geodetic Survey includes tape calibrating device developed in Department of Civil Engineering Laboratories of Case Institute of Technology. Shown above is apparatus used to fix zero at one end of calibrating device and, at right, micrometer and wheel at observing end. Micrometer is set in system of precision ball bearings for accuracy in readings. Mapping and Map Projection An average of four plane-table parties mapped topography from August 1940 to August 1946. These parties worked in strategic areas where major freeway programs existed. The recommended city survey mapping scale-1 in. = 200ft. with a 2-ft contour interval-was used in the work. The mapping is executed in strips which range from 1,000 to 4,000 ft in width. Since this mapping is for the immediate and specific purpose of location and line design of the freeway and interchange system, considerably more culture is plotted than would be otherwise. All buildings and residences, except garages, are plotted in order to present the requisite criteria for paper location to minimize condemnation proceedings. Accordingly, progress was slowed up and in the six years only 15.66 sq miles were mapped. The plane-table sheets are enlarged to 1 in = 100 ft by means of an ideograph or precision pantograph, and the location and line design is based directly on the physical data of these enlargements. The above mentioned freeway and interchange system, as an anticipated complete expanded program, is estimated to be a $150,000,00 project. This is just one of the many projects which should be on the future planning program for a city the size of Cleveland. Therefore it is a natural presumption that the existing survey control in the Cleveland area, together with the existing plane-table mapping, should save many years of preliminary survey time. Furthermore, the cost of obtaining these survey data has been jointly borne by those public agencies which, in all probability, will be responsible for the greatest portion of future construction activities. The plane rectangular coordinate system is used for mapping. The plane is tangent near the center of the county. Since the county has a maximum dimension of 30 miles in the east-west direction and 24 miles in the north-south direction, no noticeable discrepancies should result by the use of the projection at the prescribed site. In November 1947, a contract was granted the Aero Service Corp. of Philadelphia to photograph Cuyahoga County from the air and map a portion of it on a scale of 1 in. = 200 ft with a 2-ft contour interval. The resulting maps are to be reproduced by the Brock photogrammetric method.
Equipment Innovations Several new features in the way of equipment have been developed and used to considerable advantage on the geodetic survey. Mounted red or green neon or fluorescent tubes, 4 ft in length, have decidedly facilitated triangulation observations in the urban area where the myriad of white lights makes it difficult to find, in the theodolite scope, an ordinary signal lamp target of the U.S. Coast and Geodetic Survey type. The necessary transformers permit the use of the ordinary 110-v city current or the 6-v wet-cell automobile battery. The new equipment features were developed in the Department of Civil Engineering Laboratories of Case Institute of Technology-the Case taping buck and a device for calibrating tapes. The Case taping buck has a movable strip of stainless steel of tape thickness alongside of which the tape is stretched so that a scratch on the tape is brought to colineation with a scratch on the strip. The strip is then clamped. The strip is attached to a head which is also adjustable for line and rough distance. One leg of the buck is detachable at curve height with an inner pointed shoe which permits leveling the buck at curbs or in rough terrain. The distinctive feature about the tape calibrating device is the employment of a micrometer in a system of precision ball bearings for obtaining precision readings on the base tape and the tape which is being calibrated. A number of other unique features were employed in the construction of the traverse tripods, traverse rods, tent frames, signal lamps, and containers for transporting the survey equipment to the field. Underground Survey of Utilities In January 1939, the Cleveland Regional Underground Survey was established with the Works Projects Administration contributing the major quantity of manpower. Following the withdrawal of WPA sponsorship, the State Highway Department and the City of Cleveland carried the burden of the sponsorship until March 1, 1944, when all sponsorship ceased. "Book Sheets," the final product of the Underground Survey, are on a scale of 1 in. = 20 ft and are approximately 2x2 1/2 ft in size. Over 600 of these cloth tracings have been completed as of February 1, 1944. In addition, 66 strip cloth tracings, each 2x5 ft on a scale of 1 in. = 20 ft, have been completed and used extensively by the Water Department. Over 10,000 utility points (electric, gas, water, telephone, telegraph, and steam) are available for inspection at Underground Survey Headquarters. Cooperation with U.S.C. & G.S. In November 1943, the U.S. Coast and Geodetic Survey began observing on a triangulation chain the West 81° 30' meridian south from Cleveland. The Survey tied in to the four old Lake Survey stations and nine stations in the Cleveland net. It used five of its won Bilby towers, ranging from 90 to 110 ft, and at the remaining stations it used the towers constructed by the Cleveland Survey. The Coast Survey in 1944 expressed its willingness to provide horizontal and vertical control to cities devoid of such, which were planning large-scale postwar construction programs-another commendable gesture. The WPA expended $464,000 on the Cleveland Regional Geodetic Survey and $421,000 on the Cleveland Underground Survey during its period of sponsorship which concluded July 31, 1942. As of January 1, 1948, the remaining sponsors have expended $795,000 on the geodetic survey and $139,000 on the underground survey. In addition, as of January 1, 1948, the sponsors have been credited for space, truck, instrument, and equipment rental in the amount of $85,000 for the geodetic survey and $24,000 for the underground survey. Recapitulating -- a total of $1,148,00 has been expended on the geodetic survey (or an average of approximately $100,000 per year) and a total of $163,000 has been expended on the underground survey (or an average of $32,000 a year for the life of that survey). Obviously, no one sponsor could have afforded to foot the bill for this horizontal and vertical control and the mapping executed to date in Cuyahoga County. The total cost of the Cleveland survey, however, should not be averaged over the years of its accomplishment, since the control, as established, will benefit Greater Cleveland and Cuyahoga County for many years to come.
Cleveland Digital Library Webmaster Last updated April 10, 2002 This electronic, World Wide Web edition of the "Cleveland Regional Geodetic Survey," by G. Brooks Earnest, contains the complete text as found in the reprint of the original Civil Engineering article from 1948. The site is hosted by the Cleveland State University Library and is presented here with the permission of Civil Engineering, which retains all intellectual property rights to the work itself. We thank them for their help and generosity. ã Website copyright 2002 by Cleveland State University. All rights reserved.
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