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4.3 Determination of Strategies and Assignment of Resources
The determination of strategies could imply a series of decision rules based on economic analysis that match deficiency ratings with appropriate actions. Well-designed GIS/PMS should have direct links to decision modules so that the strategies can be readily determined. The strategy module should have direct access to the GIS/PMS database, and the model results should be entered directly into the database.

A GIS would enrich the decision-making process by incorporating other types of data that could not easily be brought into the process without the ability to relate data spatially. One of the example is accident analysis requires the correlation of a number of explanatory roadway and environmental variables such as roadway geometrics, weather conditions, traffic volumes, signage, signalization, lighting, and pavement condition. A GIS can serve as the integrator of all transportation activities (e.g., pavement management, accident analysis, sign and signal inventories and planning), as well as the link to other agencies with overlapping data needs (e.g., planning, environmental resources, utilities).

5. Essential Components of GIS/PMS
A number of essential analytical capabilities that should be included in comprehensive GIS/PMS have been identified:

• data base editor for storing and editing pavement condition data and other data to be used in the analysis;
• Formula editing of data base fields that facilitates the computation of new relationships such as an overall condition rating;
• Univariate statistics (min, max, sum, mean and standard deviation), e.g., to compute the total lane miles with a deficiency rating greater than 90; multiple regression to compute deterioration equations; correlation to compute dependence between possible explanatory variables such as truck volumes, weather, and soil conditions and pavement condition;
• Charting (e.g., pie charts and bar charts) to enhance the understandability of the data and make it easier to communicate results to decision makers, politicians, and citizen groups;
• Matrix tools for creating and manipulating origin-destination tables, travel time matrices, and other one and two-dimensional matrices used in transportation models for shortest path detour determination and traffic assignment;
• A set of useful transportation models and algorithms including shortest path, traffic assignment, vehicle routing (for efficient reallocation of trucks and equipment), and traveling salesman (for the delivery of materials to several construction sites); and
• Links to external procedures such as life cycle costing, decision analysis, shortest path, and traffic assignment.

6. Current Application and Case Studies
Though the pilot scale project is being initiated now to establish a comprehensive database in GIS environment for roads and road information management system at the national level, small regional studies with limited scope have already been undertaken by the Institute.

Data for about 360 km under the jurisdiction of PWD and MCD roads under the study on evaluation of Delhi roads for maintenance and rehabilitation is being created in GIS environment. The existing road network map of Delhi has been prepared in GIS environment, from which the various categorized roads are identified and created as separate layers. The network being covered in the study is shown in figure 1. The various field surveys were carried out to collect the highway condition data. A computer database is used to sort and store the collected data and attached to the relevant layers in GIS environment. Figure 2 shows the pavement condition, roughness, traffic and axle loading scenario on PWD Roads (a typical zone map). A simple criterion has been used to evaluate repair or preservation strategies for 10 years for the selected network. Figure 3 shows the year wise maintenance strategies of the inner ring road.

Figure 1: Road Map of Delhi




Figure 2: Pavement Condition, Roughness, Traffic and Axle Loading Scenario on PWD Roads (Zone – 4)




Figure 3: Year wise Maintenance and Rehabilitation for Inner Ring Road
7. Concluding Remarks
GIS can be a very important tool in a decision support system by facilitating preparation, analysis, display, and management of highway data in a geographical platform. In particular, pavement management is a decision process that could benefit from the use of a geographical platform provided by GIS, because road networks are inherently geographic. Spatial considerations are not only essential in analyzing the different road related activities, but also can vastly improve the quality of the decision-making process.