Figure 2: AIRPORTS main menu screen
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The aim of the AIRPORTS system is not just repair the pavement once failed but time maintenance to occur when possible at a point just before pavement cracking becomes visible.
This will allow a cheaper overlay to be applied, at a time that suites the Authority, and before the integrity of the internal layers of the pavement have been compromised.
Keeping the above items in mind, the AIRPORTS system was developed to bring together all of the pertinent data with budgetary constraints and allow the user to manage his pavement.
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The layout shown below reflects this integration of analysis and detail as well as the mapping link added to allow user-friendly presentation of data from the system.
This GIS linkage coupled with flexible graphing and customizable reporting functions enable easy access to all data within the system.
Additionally, keeping the international perspective in mind, the AIRPORTS system operates in any of eight languages including Chinese.
Feature Level Data Summary Screen
The health of the network can be monitored graphically with a wide selection of data easily graphed to demonstrate the condition of the network. Point and click selection keeps operator input to a minimum. Graphics may be plotted in colour or black and white.
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Figure 3: AIRPORTS feature data screen
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An example Friction data plot
Access to summary screens, such as Figure 5 below, for rehabilitation options by feature showing the timing, costs and cost benefit ratios for each alternative is provided. Review of multiple budget scenarios is available to review the impact of selected options resulting from various budget scenarios ranging from no funding to unlimited funding
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Figure 4: Typical Network level graphics
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Typical Network level graphics
Access to summary screens, such as Figure 5 below, for rehabilitation options by feature showing the timing, costs and cost benefit ratios for each alternative is provided. Review of multiple budget scenarios is available to review the impact of selected options resulting from various budget scenarios ranging from no funding to unlimited funding
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Figure 5: Comparing optimization results
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Typical Network level graphics
Access to summary screens, such as Figure 5 below, for rehabilitation options by feature showing the timing, costs and cost benefit ratios for each alternative is provided. Review of multiple budget scenarios is available to review the impact of selected options resulting from various budget scenarios ranging from no funding to unlimited funding
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Figure 5: Comparing optimization results
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The PMS – Pavement Modelling
The heart of AIRPORTS is PERS®. In summary PERS® allows three main elements:
- Models for determining the pavement performance based on mechanistic (analytical) principles
- Models for quantifying the effects of pavement conditions
- Methods for selecting the optimal combination of maintenance and rehabilitation alternatives over a number of budget years
PERS® utilizes an incremental-recursive model for calculating pavement performance. For each increment in time the damage caused by traffic loading and by time related effects is calculated, and the new pavement condition is then used recursively as input to the next time increment. (2)
The Odemark—Boussinesq equations are used to calculate the critical stresses and strains in the pavement layers. The user has the option to use the results of the Odemark – Boussinesq equations or calibrate the factors used by Odemark-Boussinesq using WES5.
Inputs to the PERS® system include the data previously discussed as well as budget information, anywhere up to 40 alternative rehabilitation strategies, limits on the effect each alternative has on the pavement if applied, seasonal factors affecting the system, and all historical data available.
As seen below in figure 6, the performance of the pavement is plotted through the data points of past measurements to determine the future needs.
PERS®
PERS® uses the past history of the pavement to determine it’s future performance. Thus the user is able to graphically test the application of a rehabilitation treatment and see how the application of a particular treatment will perform. If the user would like to lock in this treatment, the treatment can become a "forced solution" where no other alternative can be used.
The timing of the alternative can also be locked in to enable programming of multiple projects. On the other side of the coin, an alternative can be locked out so that the system can never choose the alternative. For example, a porous friction overlay may be inappropriate for use on an apron and thus the system can be told not to use this alternative. Or, the system can be told to use a particular alternative at a particular point in time.
Maintenance and rehabilitation recommendations from the PAVER system can be used to either lock in a treatment or the structural modeling may over ride the PAVER recommendation in light of the structural analysis. The user has control over the basic parameters of the optimization system including: material types, aircraft types, wheel configurations, user cost relationships, alternative types and program limits. Each material type has a damage function to control structural deterioration, roughness, and friction. |
Figure 6: Historical data with future performance.
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For each alternative the user may define the effect of the option on roughness, friction, PCI, residual life of the pavement and it’s residual value within the system and it’s costs. The user sets limits for structural damage to layer one, roughness minimum and maximums, allowable rutting depths, levels of friction, residual life of the wearing course, PCI intervention levels. The system tries each alternative available to see if it can meet the limits set, and then to see if the alternative can be fit into the existing budgets. Those alternatives that have a higher agency cost and a higher overall cost are eliminated so that only the most efficient strategies are retained.
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