Geosistemas y Tecnología Avanzada, S.A.
Louis Berger International
Guatemala has a 1:6
relation of paved/unpaved roads for the whole country. The unpaved roads, classified as Tertiary
roads, include nearly 22,000 kilometers
(approximately 14,000 miles), from which 12,700 kilometers had not been
inventoried. Since the beginning of the
rainy season was close, the need for a rapid response required a physical
inventory using GPS, and the building of a database with a video aided
system. The Road Information System was
built on Arc View GIS, and included a segmentation analysis of each road
associated to an alphanumeric and video database. The Nationwide Unpaved Roads
Network Inventory had the ability to manage the maintenance of the roads, and
the prevention of natural disasters.
Guatemala Map Figure 1
Guatemala Road Map Figure 2
Precipitation Map of Guatemala Figure 3
Damage Analysis of a Road Figure
4
Recommended Labor for a Road Figure 5
Mean Velocity for Driving Figure
6
Screen Shot 1 Figure 7
Screen Shot 2 Figure 8
Screen Shot 3 Figure 9
The Guatemala unpaved roads network reaches 25,000 kilometers long. A
large amount of these roads are from 4 to 18 hours driving away from the
Capital, making them very difficult to access. Most of the unpaved roads are
not well designed, do not contain a drainage system, and the cover is
non-consolidated, making them highly vulnerable to the rainwater streams.
The General Roads Administration of Guatemala (GRA from now on) recently
realized the need to develop a Road Inventory System for Managing and Planning
purposes. The Inventory System should
include enough information to establish maintenance programs and be able to
deal with prevention for natural disasters.
To address a quick reply the GRA created a special commission to develop
the Unpaved Road Network Inventory.
Since the rainy season was close, the Inventory had to be done in less
than 5 months. Thus, working with 4
brigades, and considering the high rural index, each of them had to cover more
than 50 km per workday. The solution for the field mapping and data acquisition
came out by using GPS receivers to map the entire unpaved roads network while
video taping each road for the construction of the database.
The primary objective of this project was to develop a GIS based Unpaved
Roads Network Inventory with a strong database capable of managing, planning
and preventing natural disasters for the entire road network.
Guatemala is a small country located in Central America. Its population reaches 10,850,430 inhabitants and the country extends for 108,750 square kilometers. See Figure 1. Guatemala is divided in several geographic provinces that conform a very rough and varied topography. Even when the country is very small each of this provinces provide a unique eco-system, with as many as six different microclimates per region.
Guatemala’s population is concentrated in Guatemala City (Capital) with
nearly 30% of the entire population residing in it; the rest of the population
is evenly distributed throughout the country.
This gives the country a very high rural and dispersion index. As pointed out early, most of the small cities
(communities) are from 4 to 18 hours driving away from the Capital. Besides the Guatemala City, there is no
other city with more than 300,000
residents.
Many of Guatemala’s roads were paved or reconditioned in the past four
years, reaching an eighteen percent value of paved roads nationwide. Most of the unpaved roads are very difficult
to access, and most of the time they
require 4x4 vehicles. See Figure 2.
It was a major concern of the past and current Government to implement a
GIS based support database to fully manage the unpaved roads network. Since most of these roads connect rural
communities to the Primary roads it is vital to have them in good standing
condition. During 1998, Mitch hurricane
brought unconventional heavy rains that destroyed many tertiary roads, leaving
thousands of people isolated. This Tertiary Roads Inventory will have the
capability to evaluate the potential risk of destruction due to weather
conditions and to address the best response to each event.
UNPAVED
ROADS INVENTORY
The Inventory was done using a Magellan ProMark X GPS receiver to map
each road at a sampling rate of one position per second. Each brigade consisted of one GPS receiver,
one video recording unit, and one notebook computer. The clock of the video recording unit was calibrated with the
Universal Time of the GPS so every second of recording had a corresponding GPS
position. This was done with the
intention of using the video recording and its audio narration to build an
alphanumeric database and a video library.
The Inventory required that each road be segmented in units of equal
physical conditions (i.e. width of the road, leveling, types of ditch and
waterways, slope percentage, surface composition, mean driving velocity, signs,
etcetera). This segmentation was done
based on the images and the audio analysis of the video recordings. Each road was divided in segments ranging
from 50 to 500 meters long with the same physical characteristics.
By noting the time of the beginning and end of each video segment, the
GPS positions were segmented as well using the Universal Time as clip element
to create a polyline on Arc View GIS.
Each polyline (segment) had associated a database of 102 fields giving
an approximate of 6.5 million records.
The database included the following sections: description of the road, road settings, description of surroundings,
recommended work, and risk assessment.
The full process can be divided in the following elements:
The final GIS based inventory had the ability to relate the geo-spatial
database with the alphanumeric database and the video library.
As can be noted on the following pictures, the Unpaved Roads Network GIS
shows several interesting analysis possibilities for inventory purposes,
maintenance, prevention of natural disasters, as well as routing information
and site selection.
The project presented here combines the use of GPS and Video recordings
in the creation of a Road Network database.
The project proved to be a highly effective and efficient way to build
the GIS based Network Inventory. The acquisition of data by video means produce
not only a high end database, but also supply an endless analysis tool for
future planning, management, and risk assessment.
The author wishes to thank all the Louis Berger International team that collected the data. Special thanks to Iris S. Hernandez, Raul Porras, Frederic Frot, Mauricio Amaya, Guillermo Quezada and Monica Berger, all members of GEOSISTEC.
Luis Alejandro Fernández
Geosistemas y Tecnología Avanzada, S. A.
21 Calle 10-71 Zona 13, Aurora II
Guatemala 01013,
Guatemala.
Phone: 00 502 331 5792
Fax: 00 502 361 2689
E-mail: laf@terra.com.gt
Louis Berger
International
Dirección General de Caminos
Finca Nacional La Aurora, Módulo 5
Guatemala 01013,
Guatemala.
Phone: 00 502 440 3780
Fax: 00 502 440 3781
