AU-CPM: A SCHEDULING INTERFACE FOR AUTO-CAD

INTRODUCTION

Computer aided drafting (CAD) shares a place with the word processor, spreadsheet, and database manager as one of the essential tools for use on the microcomputer. CAD distinguishes itself from these other character-based tools in that it is graphics-based. AutoCAD, which was introduced for use on the microcomputer in 1982, has emerged as the standard by which other CAD programs are now measured. Perhaps one of the reasons for its success is that AutoCAD was developed with an open architecture, i.e. one designed to be changed. The software is loaded with programming tools and features that allow it to be configured to virtually any application. In fact, increased drawing productivity over hand methods is often possible only through application-specific customization of the software. Several hundred customizations of AutoCAD, spanning the full range of technical drawing, have been published to date.

While applications have developed rapidly within the architecture and engineering disciplines, relatively little has been done within the construction field. This is perhaps due to the predominance of financial and statistical activities carried out by spreadsheet and database programs. The emergence of the electronic drawing as the pivotal document for future building contracts will inevitably bring CAD software to the construction office, if not the construction site itself. Software is already available which produces a cost estimate directly from an electronic drawing; e.g.  TIMBERLINE's CADLINK with AutoCAD.

AU-CPM demonstrates one application of CAD to the construction environment. Once a schedule has been developed for logic and completeness, either by hand or computerized methods, a presentation quality drawing can be easily produced on the computer using AU-CPM.

HISTORY

AU-CPM was initially developed to assist Building Science students and faculty at Auburn in the production of quality schedule drawings. Students are required to produce time-scaled CPM drawings in scheduling and terminal project classes. Traditionally these schedules have been of poor presentation quality. Some students attempted to overcome their drafting deficiencies by using plot features of the available scheduling software, e.g. Primavision, Timeline, and Aldergrapf. Although these programs have extremely valuable data-based scheduling features, the readability of the time-scaled CPM plots they produce is marginal at best. Very little control over the sizing and placement of drawing information is provided to the scheduler. A few students were able to produce schedules with CAD software such as AutoCAD. This approach produced the best looking schedules but with an enormous investment in time, especially for those unfamiliar with the software. Developing a "friendly" scheduling interface for AutoCAD, a tool to produce presentation quality schedules in a short period of time, seemed to be the best of all possible solutions.

Program development began in the Winter of 1988. Shortly thereafter a prototype of the program was used to produce a 120 day schedule for a local contractor. This program would only produce pure-logic diagrams and showed initial promise for overcoming the graphics problems of scheduling software. The next version was developed for students to produce time-scaled drawings for their terminal projects. The first student drawings were a success, and suggestions for improvements and more automatic processes were added to the program. Students, unfamiliar with AutoCAD, have been able to produce a finished time-scaled schedule of 100 activities in four to six hours complete with title block, legend, border, and calendar.

The current program (version 1.01) has combined the different drawing formats into one program and allows the user to select the one that best suits his needs. Future versions will add a Precedence diagramming method and provide an option for specifying attributes that can be shown with activities. Also being developed is a facility to export task data from an AU-CPM schedule directly into scheduling programs, Lotus 123 or databases.

PROGRAM OPERATIONS

Installing The Program:

An installation batch file has been written to help install the software on the hard disk. Good file management practices have been observed to keep AU-CPM program files separate from AutoCAD program and drawing files. The installation batch file creates a separate directory for the storage of AU-CPM program files and a default directory for storing the schedule drawings. A batch file for starting the program is used to assign all AutoCAD environment settings, including default directory, path, and memory requirements for AutoCAD and Auto-LISP. A READ.ME file provides brief instructions for installing and running AU-CPM.

The hardware required to run the AU-CPM interface is the same as that needed for the operation of AutoCAD. The program consists of about 500,000 bytes of menu, lisp, and drawing files. AutoCAD must have been installed on the hard disk in order for AU-CPM to operate. The program is designed to run with AutoCAD Release 9 or higher.

Using The Program:

Upon entering AU-CPM, a welcome message informs the user that AU-CPM is not an automatic scheduling program, but a customization of AutoCAD that aids in producing a previously designed CPM plot. The student is reminded that the program cannot draw the logic for him, but can help him display his ideas.

Upon activating the program, the scheduler is guided into AutoCAD, at which point he chooses a drawing environment for generating one of three types of schedules: CPM time-scaled, CPM Logic, or Bar chart. The appropriate menu system is loaded, providing access to custom built scheduling commands selected from pull-down menus at the top of the drawing screen. These interactive commands are written in the LISP programming language to give them the "look and feel" of standard AutoCAD commands. For example, upon selecting the activity command, the scheduler is prompted for the starting node, activity description, and duration. The program then automatically generates all line work, arrowheads, nodes, and other desired information for that activity, then cycles back for the next activity. Linetype designations for critical path, standard, dummy, or float lines can be changed at any point in the process. All text information is stored as "attribute" data for export to other programs. Custom editing commands are also located in the pull-down menus for easy access. Simplicity comes from including only the standard AutoCAD commands that assist in drawing schedules, and moving all others off stage to the side screen menus.

The pull-down menus call upon three basic types of scheduling commands:

MAJOR PROGRAM FEATURES:

Initialization

The initialization menu is the first item to appear upon entering the AutoCAD drawing editor. From this menu, the scheduler selects drawing type and drawing sheet size. One of five drawing template files, representing one of the standard sheet sizes (A through E), is automatically loaded with the proper scheduling menu. The initial size will provide the necessary guidelines for the spacing of activities. The scheduler may change sheet sizes by stretching the borders of the paper if more drafting space is needed. Sheet size selection is important for people unfamiliar with scaling and plotting of drawings. This feature allows the scheduler to know which sheet size he is working on, so the plotted drawing will fit on the required sheet and be readable.

Calendar Generation

Each of the template drawings contain a calendar, positioned and sized for the appropriate sheet. The calendar has been developed to show both calendar and work days of the project. Consecutive work days are in place when the scheduler begins, leaving the calendar dates to be added semi-automatically by the program. A pick and place method was selected for this operation because of the variables associated with doing schedules that begin on different dates. The scheduler picks the start point of a date sequence on the drawing, and then selects date numbers from a side menu. Dates are automatically positioned and drawn in the calendar boxes. Month descriptions are also places this way.

Title block and Legend

A standard title block and legend has been created to be applied to any drawing. The title block is added by selecting the title block command on the pull-down menu and placing it on the drawing. The command then prompts the scheduler for project name, drawing date and other title information. The legend contains the necessary symbols used in each type drawing type and can be placed anywhere on the drawing. Custom designed title blocks and legends may be easily substituted using standard AutoCAD block manipulating procedures.

Editing Features

Several custom editing features have been added to facilitate the inevitable changes of the schedule. Attributes, such as activity and node descriptions, can be quickly changed or replaced by simply tagging the entity and typing in the correction. The MOVE, and STRETCH commands assist in changing and relocating activity and link lines. Repeated activities can be copied to new locations with the COPY command. Most edit commands repeat automatically, providing additional speed to the process.

IMPLEMENTATION

Students in the Building Science program at Auburn are now being introduced to the software as a regular part of their scheduling course and advanced computer course. A number of students have produced time-scaled CPM schedules for projects which contain more than 100 activities. Most of the students have minimal exposure to AutoCAD, but have little trouble using the program. The large schedules are similar in appearance to the examples shown in figures 1 through 3.

The software has also been used on consulting projects. The response from industry clients has been positive, and many are asking for copies of the software to add to their existing systems. The software has been used by instructors to draw classroom examples, which can later be modified or changed. The ease with which examples and problems can be updated helps both the student and the faculty member keep pace with progress.

The time required to produce a schedule varies with the experience of the scheduler. The first attempt takes the longest amount of time and is usually six to eight hours. A second schedule of the same length can take as little as 3 hours to input, edit, and plot. The speed will vary depending on the complexity of the schedule and the experience of the scheduler.

FUTURE DEVELOPMENTS

As more students and schedulers use AU-CPM, excellent suggestions for improvements have emerged. Also, as facility is gained with the AutoCAD programming tools, additional possibilities have surfaced. The following is a list of additional features currently planned as program enhancements:

Help

Develop context-sensitive help facility to speed the learning process of the program.

Attributes

Develop feature to allow the scheduler to define unique activity attributes. The scheduler would be prompted for values of these pre-selected attributes at the time of activity placement.

Calendar

Improve the calendar facility to automatically number the calendar days given the project start and end date.

Data Export

Develop an automatic report generating feature to extract information for the drawing. This report could be in several different format options(ASCII, LOTUS, DBASE) and contain different information (1-node, J-node, Duration, description, etc).

Data Import

Develop ability to import information(e.g. calendar, node numbers, descriptions, etc.) from a DBASE, LOTUS, or ACSII file.

Precedence Diagram

Develop a fourth schedule type option, which will produce precedence diagrams, showing activity on node.

CONCLUSIONS

There are several advantages of using a CAD customization for drawing schedules over all other methods available. Schedule drawings are produced with the highest precision and presentation quality possible. The speed of schedule creation and alteration allows the scheduler more time to review scheduling logic. As in all computer files, one schedule drawing can serve as a template file for building a similar one. Also, sections of one schedule can be easily cut and pasted into a new one. Exciting possibilities exist for transporting scheduling data to and from the electronic schedule drawing.

AU-CPM has been used for both classroom and industry applications. The response from students, professors, and constructors has been very positive. Construction students at Auburn now have a tool for quickly producing high quality CPM or Bar chart schedules. In addition, the program has the potential for becoming a valuable tool for the construction industry.

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