CADD Modernization at Maine DOT
By Dennis Folsom
Over the past two years, Maine DOT has been modernizing its Computer Aided Drafting
and Design (CADD) system. The scope of this work includes migration from the DEC VMS
environment to Windows NT, updating 3-D modeling and design software, implementing a
different suite of drafting software, updating drafting standards, and more closely
integrating the design and drafting components. It has been a challenge to implement all
of these changes, while maintaining production.
Why are we changing? In February, 1997, GDS Corporation announced that they
would discontinue the marketing and support of the GDS drafting software in the United
States, and that they would provide support during a three year transition period. Our old
CADD system ran on a specialized computing environment (DEC VMS operating system on VAX
and Alpha hardware). To reduce system support requirements, MDOT is striving to
consolidate applications on Microsoft Windows NT. Infrasoft Corporation has moved to a new
generation of their 3-D terrain modeling and highway design software, which runs on
Windows NT. This new system, MX, replaces their older MOSS software.
How are the data and drawings developed in our CADD system? Our ground survey
data is first collected through a system called SDMS (Survey Data Management
System), from AASHTO (American Association of State Highway & Transportation
Officials). Maine DOT is one of the AASHTO member departments who participated in the
development of SDMS. Data is recorded in a handheld computer which takes readings directly
from the survey instruments, as well as identification and comments entered by the
operator.
As the next step, the SDMS data is fed though in-house conversion programs into MX,
from Infrasoft Corporation. MX is used to develop a 3-D model of the ground, with all of
the relevant features such as buildings, roads, driveways, trees, etc. located on it. MX
is then used to develop the horizontal and vertical alignment of the proposed or
reconstructed roadway. MX computes and extracts valuable design data from the 3-D model,
such as profiles and cross sections of the existing ground. On projects where a
significant amount of roadway reconstruction is proposed, MX is used to develop a 3-D
model of the design.
Drawings, made from the survey and design models, are passed to our drafting software, MicroStation,
from Bentley Systems, Inc. Additional details, such as property ownership and right of way
information are added using MicroStation. Typical sets of contract plans often run over
100 sheets. The MicroStation drafting is accomplished using a combination of automated and
manual methods. We are continually developing macros, settings files, and other shortcuts,
to take the drudgery out of drafting and increase productivity.
We are now implementing GeoPAK Bridge and GeoPAK Rebar to further
automate the bridge design and drafting processes. The Bridge product is a tool kit for
developing a 3-D model of the proposed bridge in MicroStation. It does many geometric
calculations that are very difficult and laborious to do otherwise. The Rebar product
helps with the layout of reinforcing steel, checking for interferences, and the
calculation of quantities.
Notes on our Product Selections We are often asked why we are using these
particular products. I will comment on our two major CADD system components.
MicroStation: AutoCAD is almost a "household word" that many people
equate with PC-based CADD systems. However, MicroStation is the system that is used by at
least 46 of the state Departments of Transportation around the USA. MicroStation is also
used in many engineering firms, large and small. MicroStation was developed as an update
and replacement for the traditional Intergraph systems that ran on the larger computers.
AutoCAD started out as a small system and has "grown up" to a similar level of
capability to MicroStation. Both products have excellent features and capabilities. The
balance between complexity and ease of use is about the same with both. The costs of the
full-featured versions are similar. Through an RFP process, the selection committee
weighed the pros and cons and chose the MicroStation proposal from Bentley Systems.
MicroStation has dealt very well with the need to read and write AutoCAD files. This
enables us to share data with AutoCAD shops much easier than we could with GDS. We have
already benefited from the ability to share information, add-on utilities, tricks and
tips, etc. with our counterparts in other state DOT's.
MX: In 1999, we conducted an RFP process where we again looked at other highway
design software. Several of the better known names in this field did not respond due to
the requirements that we specified. One of the respondents failed to meet the mandatory
requirements stated in the RFP. We found that the 3D modeling technology of MX is superior
to that used by other systems that we have reviewed. MX provided an appropriate evolution
for our needs, keeping the technical features of the MOSS software that we had
incorporated into our original CADD configuration. Any good survey modeling and highway
design software system is complex. We found that MX has addressed the ease of use features
that are now expected. Also, the costs of the MX product and the migration were lower than
with the other finalist.
The states are not as unified in the selection of highway design software as they are
in drafting software. Other state DOT’s using MX include New Hampshire, Indiana and
Colorado. We continue to share information with our counterparts at New Hampshire DOT and
at some of the consultant engineering firms that work for both states.
This image is from a rendered 3D model of a road design. MX
software merged models of the proposed design with the ground survey. MicroStation
software was used to add light sources, and to make minor edits. The resulting 3D image
clearly illustrates what a design will look like, and enables engineers to analyze the
design in new ways.
Why is all this taking so long? There is no such thing as an out-of-the-box CADD
system that is ready to run for a state Department of Transportation. All of the
DOT’s have had to go through a similar process of setting up their standards and
configurations, adapting their CADD system to their engineering practices.
We have a very complex interrelationship among all of the various units that are
involved in the development of a project. Projects are developed with input from the
following disciplines: survey, highway, right of way, utilities, bridge, environment,
geotechnical, traffic, construction maintenance, and public hearings.
We have been working on data structures, standards, and user interface customizations
designed to integrate all the project components into a system that that will facilitate
further automation. Without standardization, automation is impossible. Our automated
procedures can do some operations in minutes that used to take days by manual methods.
We are now in a refinement phase, where every aspect of our new CADD system is being
tested in actual use. We are making changes and corrections needed to make the system
easier to use and more productive. Approximately half of our CADD work is now done in the
new system. Now that we have most of the problems solved, the pace should accelerate for
the remainder of the transition.
I hope this article has conveyed an understanding of our CADD Modernization project. I
can be called at 287-3245 or e-mail dennis.folsom@state.me.us
if you have questions.
Dennis Folsom, a Registered Professional Engineer, is the manager of the Engineering
Support Group in Maine DOT's Information Systems Division. Dennis has 30+ years of
experience in the engineering, management and automation aspects of the highway field, in
State and Federal government positions. |
