Bridge Management System implementation in Italy: Pontis and other BMS application in Italy

Transcription

1 Bridge Management System implementation in Italy: Pontis and other BMS application in Italy E. Fruguglietti G. Pasqualato E. Spallarossa Archimede srl ABSTRACT: This paper describes different inspection and maintenance management methods approaches and underlines asset management state of the art within the italian highways inspection company called Sineco. The paths followed to identify AASHTO Bridge Management System (BMS) (called Pontis) as the bridge management system tool that better suited the italian user necessities are described. Sineco, in fact needed a system not only for inventory and inspection data collection, but especially for programming purposes. Moreover, the study includes the description and the comparison between the two different inspection methods. The first one, the one applied within Sineco company, and the second one, the AASHTO element level inspection. The paper describes the main steps that have been followed to apply Pontis BMS to Sineco data, the main difficulties encountered during this process and the results obtained applying the system to the italian highway network, given the fact that in Sineco the AASHTO system programming feature is applied, very deepen studied and customized to obtain maintenance programs; furthemore results are refined to define annual detailed projects. To better explain the conversion method applied to translate inspection data collected by Sineco into the language needed by the Bridge Management System an example is provided, in order to give the idea of the technical study performed to identify the conversion method itself. 1 INTRODUCTION The activities described in this paper have been performed within the collaboration between Archimede s.r.l. and Sineco s.p.a. Archimede is an italian engineering company, performing design and engineering consulting and responsible on Pontis italian application. Archimede has a deep knowledge of bridge management systems and of asset management systems. This knowledge has been obtained also thanks to international contacts and experience sharing with foreign countries, both European both North American. Sineco is a private limited company that operates in the engineering sector and which controls more than 1200 Km of national motorway network. Sineco s main mission is to lend support to the managing companies of the various road and rail networks with regards to the technical activities of control, carrying out and management of civil structures, or the identification, design and planning of maintenance and updating of the infrastructures. The company concentrates in particular on controlling and supervising road structures such as bridges, viaducts and tunnels. More than 1000 structures are currently under control in the engineering sector of The cooperation was born for the general bridge maintenance programming assessment and evolved to asset management with years, in order to be keep up with times. Since 2002 the two companies have been cooperating in Pontis implementation, intended to choose the optimal bridge network maintenance or improvement policies, consistent with italian agency s usual policies, long term targets and budget constraints on the basis of inspection data recorded by Sineco. Inspections are carried out with the purpose of ascertain the consistency and safety of structures and to measure the structure state of deterioration. Thus, a great quantity of data is available, obtained from inspection procedures; what Sineco was looking for was a system that could be used both as a database, both as a management tool. The database functionality would be used to systematically store the large amount of bridge data collected, while the management functionality would use stored data for providing highway agencies maintenance and improve-

2 ment policies, predicting future needs and programming and prioritizing works and projects. 2 EVALUATION OF CANDIDATE BMS FOR USE WITHIN SINECO COMPANY A study was performed to set the bridge management systems (BMS) that best fitted Sineco needs. The study evaluated a set of commercialy-available BMS, their particular functionalities, and their adequacy for managing Sineco s clients bridge network. The study was performed on the basis of the following methodology: examination of available systems; development of a set of criteria to compare the systems; performing the system analysis on the basis of the selected criteria using custom-developed spreadsheet; evaluating systems faults and benefits on the basis of the selected criteria. Sineco was looking for a BMS system having functionalities able to integrate inventory with inspection and deterioration data in order to assess questions as: how much should be invested in bridges in order to minimize long term costs; what are the consequences of different investment levels on bridge condition performance; what projects and with which priority should be undertaken on specific bridges? Sineco chose Pontis because it assessed its own needs (different agencies with different needs might opt for a different system), being developed by AASHTO, that is a non - profit association, and being widespread among nearly all the United States, grants a systematic implementation. Furtemore using Pontis provides a systematic approach for a bridge management system application. 3 SINECO SYSTEM BRIDGE REPRESENTATION (SIOS) Sios deterioration evaluation system in characterized by a high level detail that produces numeric evaluations (index value) and graphical schemes developed for each element of each structure. For each group of structures or for each group of similar structural elements, a list of possible damages has been defined, based on experience and on deterioration processes deep study. Possible damages are defined in different ways depending on structural elements different design and concept. For inspection purposes bridges are divided into spans; for each element in each span the deterioration rate is recorded on the basis of the element inspection form (see Figure 1) and the index value is calculated. The index value is a function depending on: extention (% or the area of the element is recorded); gravity (Low, Medium, High), distress class (I, II, III); it is calculated on the basis of environment, different tests (e.g. concrete tests) and specialistic surveys (e.g. prestressed cables surveys). Figure 1. Sineco sample structural element inspection form A specialized technical software has been developed to assist digitalizing activities. This system automatically identifies and divides deterioration types on the basis both of importance classification (deterioration type) both oh gravity level (inspector evaluation). Moreover, the system calculates automatically the corresponding deteriorated areas and, on this basis, calculates the index value; all calculated index values are registered in the same database. This way it is possible to sort, group, average, determine max and min values and make statistical calculations. Index value is also used to define tha actual state of the structure, evaluating the structure context, environ-

3 ment severity and on the basis of special material testing and, eventually, special technical investigations. not provided by Pontis and/or National Bridge Inventory items. Once the correspondence between italian and Pontis items was found Sineco inventory data were moved into Pontis database. Figure 2: A single bridge decks and beams index value graphical summary 4 AASHTO/PONTIS INSPECTION DATA RECORDING METHOD In Pontis BMS, bridges are represented as sets of elements. Examples of common types of elements are decks, beams, bearings, columns, abutments, ecc.. Each element may exist in one of up to five different condition states and in one of four operating environments. Pontis uses the Commonly Recognized (CoRe) structural elements which were developed by a task group of bridge engineers from six State highway agencies and the Federal Highway Administration (FHWA). The purpose of the CoRe elements is to provide a uniform basis for data collection for bridge management systems and to facilitate sharing of information across agencies. The total quantity of the structure must be supplied setting up elements in Pontis. Figure 4: Pontis customized Inventory form Figure 5: translated drop down window data translated into the corresponding italian items Figure 3. Pontis structure representation. 5 STEPS PERFORMED FOR PONTIS APPLICATION WITHIN SINECO INVENTORY DATA Thanks to Sineco database existence the first step that was undertaken in Pontis application was to find a correspondence between typical italian items and National Bridge Inventory items. Furthermore, to help italian customers, Pontis items, drop down windows and CoRe elements with their relative condition states were translated into italian language. Moreover an agency table was created to collect data Figure 6: translated Core Elements and corresponding condition states 6 AASHTO AND SINECO CORRESPONDENCE EXAMPLE In order to enter inspection data into the Pontis database, a convention was used to translate the Index value ratings described above into the Pontis condition-state language. Different index values ranges values were used for elements with five, four and

4 three condition states. In general, the conventions used were able to translate the SIOS span level three severity classes for each distress into the bridge element level condition states using different index values ranges. The conventions established and used for this purpose were taking into account both the total deteriorated area percentage both the index value percentage increase, that measures the distress speed forwarding. For this reason for each element two tables like those in Figure 6 were prepared. Entering the tables like the one on the left for each element in each span with the index value the condition state is found; entering the tables like the one on the right with the distress forwarding respect to the previous inspection the condition state is found; in case the two tables give different results, the worst condition state is chosen. The single element quantities are then summed to pass from the span level to the total structure level, as required in Pontis. On the basis of state correspondence previously described and considering all the six spans belonging to the same and unique structure unit, the following data have been inserted in Pontis: Table 2. Pontis Deck condition states corresponding to Sios Deck index values in Table 1 qtystate elem strunit quantity tate1 tate2 TOT qtys- qtys- brkey key 3-5 xyz , ,1 278,02 0 Deteriorated concrete AREA (Total element area %) A>25% 10%<A<25% 2%<A<10% A < 2% - I.V.<3 3< I.V.<10 10< I.V.<30 30< I.V.<60 I.V.>60 Condition state 1 Condition state 2 Condition state 3 Condition state 4 Condition state 5 Figure 7: Pontis- Sios condition state correspondence: CoRe element 14 application 6.1 Practical example- conversion calculation of deck element from Sios index value to Pontis CoRe element 14 condition states For bridge xyz, consisting of 6 spans the index values in table 1 for each deck in each of the six spans have been recorded on the basis of visual inspection performed last year based on Sios method. Table 1. Sios Deck index values recorded in 2010 for each span belonging to bridge xyz Span # INDEX VALUE SIOS Deck index values per span Deck Area per span 1 1,39 268, ,38 278, ,57 278, ,93 278, ,47 278, ,03 268,02 1 Distress forwarding respect to the previous Inspection (index value increase %) D >25% 10%< D<25% 2%< D <10% D < 2% RHEAB CS1 CS2 CS3 CS4 CS 5 Condition State Corresponding CoRe element 14 condition state Figure 8: Pontis condition states 7 SIOS MAINTENANCE NEEDS CALCULATION APPROACH Based on inspection data collected through past years, SIOS method is able to forecast deterioration evolution on the basis of statistical criteria. Needs definition, intended as work priorities, is obtained, both for the entire structure, both for each element composing the bridge, from the statistical analysis of the changes in the condition states during time. This means that thanks to SIOS method Sineco can: 1 Have detailed deterioration data, complete of graphical visualization, for each element in each span of each structure in the database; 2 Have an historical deterioration archive, in order to monitor its evolution in time; 3 Define work priorities on the basis of the following criteria: indexes representing structural elements condition states; index values statistical elaborations; historical series analysis and analysis of the changes compared to previous inspections (analysis of the graphs describing deterioration evolution on the basis of the provisional statistical models); 4 Have useful data for repair works cost takeoff analysis. This predictive method in efficient for short-medium term analysis (up to ten years planning horizons) thank to the great amount of data collected performing annual inspections since This great amount of data can be used in different analysis, such as the probabilistic analysis provided by Pontis, after the data have been normalized as described in the previous chapter 6.

5 8 PONTIS MAINTENANCE NEEDS CALCULATION APPROACH On the basis of structure definition in Pontis, the network of bridges is seen not as a set of individual bridges, but as a combination of structural elements in up to four different environments (quantity of element in an environment is defined as condition unit) which interact with each other in various forms and quantities to form individual bridges. Preservation Policy, for Pontis, is a set of feasible actions associated to each structural element that, maintaining existing bridges in operation at their current level of service, assumes that operations must continue and deterioration must be detected and remedied before operations are affected, at minimum cost. The modeling approach can be summarized in the following points: 1 Divide the network of bridges into a reasonable number of elements, the sum of which would describe all bridges in the network. 2 For each element define a homogenous unit and specify set of possible conditions that the unit can be in. 3 For each condition state, define an appropriate set of feasible actions. 4 Define environments in such a way that different deterioration or cost patterns for a given element may be addressed, and so that where possible, interactions among elements can be addressed. 5 For each bridge, specify the percentage of each element in each condition state. 6 Determine the recommended preservation actions for each bridge by applying the preservation policy to each condition unit of each structure unit of each bridge. 8.1 Pontis Deterioration models Pontis provisional deterioration models are based on Markov chains probabilistic functions. A Markov decision model is a particular type of probabilistic model, in which a physical system is modeled as existing in a set of discrete states (condition units). At fixed intervals (annually), different actions may be taken on the system, each with a set of probabilities of transition of the system from one state to every other. An important characteristic of a Markov model is its memoryless quality. That is, the probability of transition depends only on the current state of the system. These and other properties of Markov decision models ensure that one may calculate the longterm equilibrium distribution that will result from following a specific policy concerning which action to take in each state. The division of the network into elements allows a development of a set of independent prediction submodels, each addressing an element in a particular environment. Initial information for the model is provided for each element through expert elicitations. For Sineco data, Markov expert models have been updated with historical data, obtaining models that were more reliable and converging respect the expert model, as many and consistent inspection data were available. 8.2 SIOS and PONTIS maintenance results comparison Comparing Sios and Pontis maintenance plans results can be summarized as follows: - Maintenance work order is compatible; - Maintenance costs are more precise in Sios method, but, anyhow, the cost evaluation in Pontis are compatible with costs calculations performed with Sios method; - Pontis allows different scenarios simulations, with a planning horizon up to 30 years. 9 CONCLUSIONS Integration of the two systems allows different simulation scenarios for different planning horizon: short, medium and long period, from five up to 30 years. Annual maintenance plans provided by the two systems can help agencies to orientate towards optimized maintenance strategies, in order to obtain budget optimization, to prevent structural deterioration growth and to reduce users risks. In particular the high level of detail provided by SIOS method is used for engineering applications such as: design of maintenance works, cost definition of maintenance works, graphical representations, maintenance needs in the short period. On the other hand, Pontis offers different scenarios simulations and maintenance rules definitions, features that are useful to optimize budgets and identify the best maintenance policy for the long period planning horizon. Moreover, as one of Pontis output is the prioritized work list, on the basis of the benefit cost ratio, the works identified by Pontis are used as input data for the Asset management tool in use within Sineco company.

6 REFERENCES Astudillo Pastor, R., Arrieta Torrealba, J.M., C. Velando Cabañas, C. & Lozano Bruna, C Decision on repair/replacement. BRIME (Bridge Management in Europe) PL Deliverable D7. Cambridge Systematics, Inc., Pontis Release 4.4 Technical Manual. Marshall, A., Robert, W., Anderson, K., Floyd, R. & Corso, F Comparison of Pontis Bridge Project Recommendations to Programmed Work for Three U.S. Transportation Agencies. 8th International Bridge Management Conference, Transportation Research Circular 498. Robert, W., Marshall, A., Shepard, R. & Aldayuz, J Pontis Bridge Management System: State of the Practice in Implementation and Development. 9th International Bridge Management Conference, Transportation Research Circular E-C049. Aldayuz José L. & Marshall Allen R Issues in deploying a bridge management system internationally. Spallarossa,E., Robert, W., Aldayuz, J., National Application of Pontis BMS models. ICOSSAR 05 Spallarossa, E., Evaluation of candidate bridge management systems for use with italian highway bridges. IABMAS 04 Sineco, Inc., Manuale di riconoscimento e valutazione anomalie Sineco, Inc., Manuale per la gestione dei dati ispettivi. Sineco, Inc., Manuale per le ispezioni alle opere d'arte. Cambridge Systematics, Inc., Pontis Release 4.4 Technical Manual. Spallarossa, E., Robert, W., Aldayuz, J., National Application of Pontis BMS models. ICOSSAR 05