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Rapid City, South Dakota Enters CADD Age

Lorraine Granger

Rapid City, a city of 50,000 in southwestern South Dakota, early in 1986 joined the ranks of U.S. cities implementing CADD systems. "We’d been thinking about such a system for 10 years," says Leonard Swanson, Director of Public Works for Rapid City.

CADD is the acronym for computer-aided design and drafting. Mapping is one of the main functions of a CADD system in a municipal government setting. Such a system can be used to digitize (convert to a digital format) map information into a geographical database. This database can then be used to create other databases at different scales so that all maps used by city departments are consistent. Other typical applications of CADD include engineering design of water and sewer systems, roadway design, and facilities management.

Before computerizing, Rapid City’s Engineering Department contracted some of the city’s mapping to a local mapping company, but did most of it by hand.

It is unusual for a city the size of Rapid City to be involved in CADD. Much of the forward-looking credit for this system acquisition must go to Swanson. Five years ago Swanson observed several CADD systems in operation. One of these was a prototype system being developed jointly by the city of Minneapolis, Minnesota, and Hennepin county, Minnesota. "That system just wasn’t ready to be marketed," says Swanson, "but I saw the time savings." It was then, according to Swanson, the decision was made "to pursue computerization as vigorously as possible."

One of the options considered by Rapid City was time-sharing on a locally based CYBER computer. This idea was rejected as too expensive. Similarly, many CADD systems on the market could not be considered because of the cost factor.

Soon after Rapid City ran into this financial brick wall, a Rapid City mapping company, Horizons, Inc., installed the DIGIMAP CADD system, developed and marketed by Albuquerque-based DIGINETICS, Inc. After observing Horizons’ system in operation, determining that the system was affordable for Rapid City, and verifying the systems’ suitability for their applications, city officials decided to purchase DIGIMAP. The system was installed in the Public Works’ Engineering Department in March 1986.

The system Rapid City purchased consisted of the following hardware and software: a MicroVAX II computer; two Tektronix graphics stations, one for editing and one for display only; three Digital Equipment Corporation (DEC) alphanumeric terminals; a digitizing table and tablet; a CalComp pen plotter; the software that accompanies a VAX computer with a VMS operating system; and a basic DIGIMAP CADD system.*

A total of three weeks of on-site system training took place – one week before system installation, and two after. Horizons’ CADD system manager, Doug Cain, has  assisted Rapid City with system implementation. According to Cain, the operators were beginning production work in about six weeks. Rapid City’s system manager, Mely Rahn, has been generally pleased with the implementation process and thinks the six-week time frame to achieve production levels was appropriate. "It’s a pretty sophisticated system," says Rahn.

Since production was begun on the system, operators have been using it about 11 and one-half hours per day. The first, and most important, project for the system has been the digitizing of data from quarter-section plats that constitute Rapid City’s 1"=100’ base maps. This data is being placed into a geographical database created and maintained by DIGIMAP’s database management software. This database stores the geographical information in a compressed format so the information takes up less space in the computer.

The estimate for the completion of this database is one to one-and-a-half years. Using this database as a starting point, additional databases with larger scales will be created. For example, other city departments may require databases at scales of 1"=500’ and 1"=1000’. The amount of detail in the databases will decrease as the scale increases and graphical details are increasingly difficult to distinguish. The only final difference in the maps of various scales will be the amount of graphical detail. Because all larger-scale databases will be created from the 1"=100’ database, all the databases will be consistent. One update of the 1"=100’ database in conjunction with the running of several short programs will automatically update all the databases.

According to Rahn, this update consistency is one of the major reasons companies and government agencies are computerizing. When an organization creates maps, if the organization is not computerized, all the maps must be updated by hand, resulting in slight differences from scale to scale.

Rahn has also been using the system in off-hours to map the city’s transportation systems off quad-scale maps at a 1"=3000’ scale. Although these maps will not include much detail, "this will give us the big picture," says Rahn.

When the digitizing of these maps is complete, other DIGIMAP programs will be used to create maps of cartographic quality. The various programs used perform automatic pre-editing, interactive editing, plot enhancement to make the maps aesthetically pleasing, and plotting of the maps with user-specified enhancements.

The city has other plans for the system as soon as the base maps are completed. Officials want to map sewer and water line networks and create plan and profile (P&P) sheets of sewer line layouts. These tasks are accomplished with various system options. For example, an interactive split-scales editing option allows users to create both the plan and the profile views on the same sheet. With the split scale activated, the top half (the plan) can be edited at a scale independent of the bottom half (the profile). Titleblocks can be added to the P&P sheet automatically, and the sheet can then be plotted on a pen or electrostatic plotter.

City officials are looking forward to adding two more workstations, which will be easily accommodated by the MicroVAX II.

Also in the plans is the purchase of engineering design software that is an optional addition to the system. Rahn also hopes to add more design software such as a coordinate geometry program.

A recent demonstration of the fully relational attribute (non-graphical) database compatible with the system showed officials the facilities management potential of their CADD system. The attribute database relates non-graphical data to graphical data. Such a database could be used by many city departments as well as time-shared by county and state agencies. For example, a city water department might want to know the date that a specific section of pipe was last replaced. A county assessor’s office could structure an attribute database that could contain information on the tax status of properties.

In addition, because Rapid City’s CADD system runs on off-the-shelf hardware, officials hope to draw on the large selection of VAX-compatible third-party software for non-engineering applications.

The Engineering Department will soon be moving to a larger building, allowing more room for hardware expansion. But, Rahn says, as with all acquisitions, system expansion primarily depends on funding levels.

Have opinions on the system changed at all since installation? Not according to Swanson. "It’s gone more smoothly than I had hoped," he says. "[System installation] has further confirmed that this was the right thing to do."

 * DIGIMAP and DIGINETICS, Inc. are trademarks of DIGINETICS, Inc. DEC, VAX, and VMS are trademarks of Digital Equipment Corporation.