How the west was mapped - The good, the bad and the ugly
Database Design and Implementation
The GIS database design effort started with the ESRI Electric, Gas and
Water/Wastewater Distribution Data Models. Comprehensive data models based on these
generic models were developed for each of the utilities. NTUA like other utilities has
specific requirements and needs beyond what existed in the prototype data models so
significant modifications were required for each utility. For example, new fields were
added to the electric model to accommodate RUS/REA assemblies. A great deal of time
and effort was spent fitting the GPS field data requirements specified by NTUA into the
ESRI Electric Distribution Data Model standard model. A number of meetings between
NTUA staff, M&M representatives and GMS personnel were held over a period of
months before the model was declared final.
A second database design effort was required. FMGPS uses a MS Access database to
define categories and permissible attribute values to be collected in the field. The
database controls what information could be collected in the field. Customization and
precise coordination of the FMGPS model with the ArcFM data models was essential so
data in the ESRI shapefiles produced by the field data collection effort could be
converted in to the format required by the ArcFM geodatabase. The FMGPS data model
consisted of 79 feature classes, accommodating 1435 data fields, and 125 Valid Value
tables.
In hindsight it may have been technically much easier to use the field data model as the
starting point for modeling the system. Refinement of the models continued for more than
a year and one half after initiation of the GPS field work – sometimes because of
situations discovered in the field and sometimes because NTUA decided that a valid
business need existed for additional or different information from the field. These
changes presented a moving target to data collectors, database and conversion developers
and GIS implementers and significantly complicated the project.
A Pilot field data collection effort was made for each utility in August 2000 – prior to
finalization of the data models. M&M and GMS used the results to finalize the QA/QC
software and conversion routines and the field data collection project was in progress.
Field Work
Field data collection was performed using Trimble ProXR GPS mapping grade data
collection equipment connected with Fujitsu pen-based computers with the, and
FMGPS™ software. All data was corrected in real time using Omni-Star ™ GPS
corrections. The equipment was attached to a custom fabricated operator harness that
permits hands-free mobility between data collection points.
GMS deployed four two-man crews to perform the fieldwork for the project. Each crew
was extensively trained on the technical aspects of the NTUA utility system. Each crew
was equipped with a Fujitsu Pen Computer, a Trimble Pro-XRS GPS receiver, and
FMGPS ™ field data collection software. In addition, each GMS vehicle had NTUA
VHF radios installed to facilitate communication. Mobility consisted of a four-wheel
drive pick-up truck and an All Terrain Vehicle for each crew.
The major challenges in the conducting the field inventory included communication,
logistics, and remoteness of portions of the NTUA service area. Often times the field
crews operated in areas of the Reservation where communication was very difficult. It
was fortunate that each crew was equipped with VHF radios programmed to operate on
all 13 of the NTUA radio frequencies. This allowed the crews to communicate with the
GMS Project Manager and with the NTUA. In addition, each crew had a Cellular phone
to aid in effective communication. Still, because of the remoteness of the area, there
were many ‘dead spots’, from which crews could not communicate.
Logistical issues in conducting the field inventory were also of great concern. Each crew
was equipped with first aid kits, inverters to charge batteries, extra batteries and cables,
emergency compressors to pump up flat tires, and other items to facilitate data collection
efficiency. It was common for a crew to be 3 hours away from any support by GMS
management, which required each crew to be self-sufficient.
The remoteness of the area may have been the greatest challenge of overcome. The
Navajo Reservation is some of the more remote area of the United States. Many areas
where the NTUA has facilities are essentially un-populated. Elevations on the
reservation generally range from 5000 to 9000 above MSL. Temperatures range from
over 105 F in the summer to –30 F in the winter. In addition, even though there are a
number of maintained primary and secondary roads on the Reservations, many of the
roads are un-maintained, and become impassable in rainy or snowy weather. Also, most
of the NTUA facilities are not located near any road, making access to facilities to
conduct the field inventory even more difficult. Some of the measures GMS employed to
cope with the remoteness of the area were the use of All Terrain Vehicles to conduct the
inventory. In addition, each crew possessed a Laser Range Finder to allow for facility
inventory when the feature was impossible to access.
