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
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