Asset management, generally, refers to a system which monitors and maintains things of value. This applies to tangible assets, such as buildings, bridges, offices, factories, etc. Asset management is a systematic process of creating inventory and managing the assets, in a cost effective manner.
Asset management in the engineering environment is a practice of managing public infrastructure assets, to achieve high returns by monitoring and maintaining the infrastructure with the objective of providing the best possible services to end-users.
IBMS – Indian Bridge Management Systems developed to create an inventory of all bridge assets on the National Highways (NH) in India, and apply a technical logic to manage the bridge assets during its life cycle. It generates detailed inventory data and condition ratings of assets, ensuring the dynamics of deterioration process are captured. This dynamism, in the deterioration process guides the inspection and rehabilitation of bridges. The system allows the users to assign priority to maintenance activity, based on the present condition of the bridge. The progressive improvement of all bridge assets is ensured over a period of time, as worst bridges, are first rehabilitated and then the less damaged bridges.
Major stakeholders in the IBMS are the Government department, which owns the bridge assets and the general public, who use the bridges. Each stakeholder has benefits, in short-term and the long-term.
Government benefits by the creation of database of all bridges in immediate present (6 months since IBMS initiation). This is the short-term benefit. In the long-term, it optimizes the utility of funds available for rehabilitation/ maintenance of the bridges.
Over a period of time, the department will be able to monitor the bridges and ensure all such bridges, which are critical are rehabilitated first and then the focus of rehabilitation will shift to those bridges, which are showing marginal distress. Once all such bridges are repaired/ rehabilitated, then, the overall efficiency of the bridges in our country will improve along with its longevity, because of its timely proper maintenance. IBMS uses the principle of ‘FRWD – First Repair the Worst Damaged’, to ensure the entire bridge inventory is rendered safe. The fear of major sudden catastrophe can be reduced to a large extent. This will assure prolonged utilization of assets.
General public, is assured over time that all bridges are being maintained immaculately and are safe for usage. They are assured proper protocol exists for inspection of any bridge, which shows signs of distress. Dynamism of distress is negated by timely and focused maintenance. Alternate routes can be identified in times of natural disaster or calamity, to enable the public travel from point A to point B.
IBMS is the largest platform in the world, with a database, which could exceed 1,50,000 bridge structures owned by a single owner. Development of the system posed its own challenge. The system to manage such a large number of asset, in a manner, where the field studies could be conducted with minimum efforts while collecting maximum details. The bridges were given a ‘Unique Identity Number’, which was the first step of the inventory creation. Then, their precise location details, in form of latitude and longitude, had to be collected in an auto-mode using the ground positioning system. Once these details are collected, the engineering properties of the bridge design, material and other technical details of the bridge are being collected. These are essential components of inventory collection process. On the completion of inventory data, the structural component rating is done using a 0 to 9 scale, to define the status of various bridge components like – Foundation, Piers, Super Structure, Deck, Scour Rating, Waterway Adequacy, Structural Status and also the Socio- Economic Parameter, which will decide the importance of the bridge, in relation to its contribution to daily social and economic activity of the area, in its immediate vicinity.
In order to ensure all bridge inventory data are captured, stored and retrieved properly, it was important to assign each bridge a unique identity number. Thereby, making it easy to understand and accord ease in data collection. Indian Highways numbers are undergoing changes, while most of the general public are used to the old highway numbering system. However, the IBMS is capable of converting the inventory data collected as per the old highway number to a ‘Bridge Identity Number’, which will have the new highway number. IBMS will also allocate the ascending chainage to bridges, from the starting point of the highway. An ascending number with the first bridge will start from the assigned number 001.
The following bridge classification system is being adopted by the IBMS:
Classification of bridge is done by a series of alpha numeric number strings, which is based on the specific details of the bridge. There are 5 such strings used to classify the bridge. They are:
National Identity Number (20 A/N)
Bridge Location Number (18N)
Bridge Classification Number (22 A/N)
Bridge Structural Rating Number (9N)
Bridge Socio- Economic Rating Number (6N)
National Identity Number: (20A/N)
National Identity Number is made of specific codes, namely:
State Code (2A)
RTO Zonal Number (2N)
Type of Road (1A)
Road Highway Number (New) (5 A/N)
Bridge Number (3N)
Bridge Location Number (18N)
Bridge Location Number is made of specific codes, namely:
Bridge Classification Number (22N/A)
Bridge Classification Number is made of specific codes, namely:
Structural Form (2N)
Material of Construction (1N)
Type of Bridge (2A)
Loading as per IRC (2N, 1A)
Age of Bridge (1N)
Traffic Lane on Bridge (1N)
Bridge Structure Crossing Features (1N)
Length of Bridge (6N)
Width of Carriage Way (5N)
Bridge Structural Rating Number (9N)
Bridge Structural Rating Number is made of specific codes, namely:
Rating for Integral and Non-Integral Deck (1N)
Rating for Superstructure (1N)
Rating for Substructure (1N)
Rating for Bank and Channel (1N)
Rating for Structural Evaluation (1N)
Rating for Deck Geometry (1N)
Rating for Vertical Clearance (1N)
Rating for Waterway Adequacy (1N)
Rating for Scour Efficiency (1N)
Socio- Economic Bridge Rating Number (6N)
Socio- Economic Bridge Rating Number is made of specific codes, namely:
Rating for Connectivity between Two Cities (1N)
Rating for Average Daily Traffic (1N)
Rating for Social Importance (1N)
Rating for Economy Growth Potential (1N)
Rating for Alternate Route (1N)
Rating for Environmental Impact (1N)
Process of Inspection
Based on these inventory and ratings codes, IBMS analyses the data to indicate the bridges, which are needed-in-depth or detailed study,for further investigation using various non-destructive testing (NDT) procedure. The initial inventory and rating codes generate the deterioration process prognosis, which are validated by the NDT procedures. A detail remedial plan is then defined for each bridge tested, based on the standard specifications for Repair, Rehabilitation and Strengthening of Bridges.
The objectives of the inspection and maintenance schedule are as follows:
(a) To improve operational availability of the structure.
(b) To prevent downtime and enhance the life of the structure.
(c) To avoid the accumulation of defects, which manifest in the form of major defects at a later date rendering the asset unserviceable for prolonged duration.
(d) To prepare database to enable the users to detect the proper timing for carrying out maintenance.
(e) To consolidate requirements of periodical maintenance through suitable agencies/ offloading.
To achieve the above objectives, the maintenance schedule has been divided into two modules. They are: –
(a) Routine Inspection and Maintenance (RIM and RMM)
(b) Detailed Inspection and Maintenance (DIM and DMM)
The first step of inspection is the detailed visual inspection, which is conducted as per various Routine Inspection Modules (RIM). The results of the RIM decide, which of the Detailed Inspection Modules (DIM) needs to be implemented. IBMS has identified, as per procedure and location of inspection, over 125 RIM’s and 90DIM’s.
The factors attended to in RIM are as under
Aesthetics of the Structure
– Cracks, crevices, spall on the surface of the structure andappearance of structure, in regard to painting and coatings.
– Loosening and widening of gap / bond in rocks, occurrence of geometric deformation and deflections in any element of the bridge.
Functionality of Structure
– Seepages identification and water tightness for all water retaining structures.
– Delamination and porosity in the structure.
– Corrosion related symptoms.
– Wearing surface and riding quality for roads, corridors, passageways etc.
Corrective Activity Post Inspection
– Grouting for control of seepage/ cracks/ porosity and patching-up of carbonation coating post grouting.
– Refilling the gaps for proper bonding in rocks.
– Local repair for correction of spalls, crevices, corrosion and local delamination as evaluated in the RIM.
– Local replacement of wearing coat/ surface as required.
Routine Activity for Aesthetics
– Painting of structure and crack filling.
– Carbonation coating over coating.
– Wearing coat and surface replacement/ overcoat.
– Removal of vegetation growth.
Most of the RIM / RMM activities are pre-scheduled and should be completed within the specified time frame, as stipulated. The activity should be succeeded with corrective measures, as required.
One of the factors that can affect the stability to cause distress is exposure of structure in different conditions, i.e., area, which is above splashing of water termed as the ‘DRY ZONE’. Area below splashing zone are termed the ‘WET ZONE’. Splashing zone is an area between the HHTL +0.20m and LLTL –0.20m.
Detailed Inspection and Maintenance (DIM / DMM)
IT is defined as the activities, which are required for each structure, irrespective of the type of usage. They are to be adhered to, at specific durations, in the age of the structure and relate to its strengths, integrity and structural safety, as defined in the maintenance schedules of the structure. DIM involves evaluation of specific parameters of the structure to define its safety and structural efficiency during its service life. These parameters include:
Strength Parameters of the Structure
– Structural Integrity (overall and specific)
– Grade of Concrete
– Corrosion Potential in Concrete/ Steel Matrix.
– Adequacy of Steel Sectional Area.
– Vibration monitoring of Structure and Deflection Evaluation under Dynamic Loading.
Balance Service Life Evaluation
– Evaluation of expected loss of service life, due to corrosion.
– Evaluation of expected service life, based on the strength parameters evaluated as per RIM.
– Evaluation of balance service life, based on the results of all parameters evaluated in RIM
Event Triggered Inspection
– Inspection for fire damaged structure.
– Inspection for structure post flooding.
– Inspection for sudden undersigned impact loading.
– Inspection post-local failure of structure.
Analysis of Data
Asset Management depends hugely on the capability of the software to conduct analysis on the data and to generate reports for various functional needs of the users’ departments. The IBMS, being a system for National Highways, is designed to provide tools to the Ministry officials to generate statistical analysis of the data and be able to answer queries related to the same. Some of the filter options are shown below:
Statistical Analysiscan be done using the IBMS. It basically enables division of database, as per the following parameters:
- a) As per the Age of the Bridge
- b) As per Daily Traffic Count
- c) As per the Type of the Bridge
- d) As per the Structural Form of the Bridge
- e) As per the Material of Construction
- f) As per the Features Crossed by the Bridge
- g) As per the Present Condition, by using Classification Count Method
- h) As per the National Highway Number
- i) As per the State, RTO District etc.
Technical Analysis of the data enables the users to define the level of deterioration in any bridge and assign proper corrective action, based on the analysis. Classification count is evaluated for each bridge post inventory and condition ratings, to enable the users differentiate the bridges for further inspection and testing requirements. Based on the inspection and testing conducted, the designer is able to define and design the remedial measures, which are required to be adopted to bring the bridge in safe zone. This cost of rehabilitation/ repairs/ retrofitting enables the users to then assign a priority to maintenance activities, using the Priority and Ranking module of IBMS
Typical analysis of data could yield results like the one given below:
Process of Priority and Ranking of Bridges
Ranking of bridges for repair is driven by a logical protocol, which is based on the cost of repair, the importance of the bridge in Social and Economic scenario and the level of deterioration defined by the ratings, as defined by the Structural Rating Number used in conjunction with the traffic on the bridge and age of bridge. The ranking module of the IBMS defines a list of bridge, which are needed to be repaired / retro-fitted as per priority and can be taken up, based on the total fund available with the Ministry. This brings in technical and socio-economic logic to the sequence of bridges to be repaired.
Ranking and priority for bridge maintenance is based on rating evaluation done in the classification stage. Priority is defined based on the observations during the classification stage. Priority is based on the observation for the following rating numbers:
- a) Bridge Structural Rating Number
- b) Socio- Economic Bridge Rating Number
- c) Type of Road
- d) Loading as per IRC
- e) Rating for Average ADT
The Critical Weightage is termed as ‘Cw’. It is, then used further in the ranking system. The‘Cw’ ensures the most needed bridges having severe distress are assigned highest weightage by an accorded value of 100. Similarly, for the ‘not so important’ bridges with least or no distress, the ‘Cw’ is accorded a least value of 10.
Once the ‘Cw’ is defined, the second step in defining priority is to evaluate which of the bridge is most frequented and lies on the important corridors with the highest load rating. This factor is defined by Importance weightage ‘Iw’.
Once the ‘Iw’ is defined, we have to evaluate if the bridge or its critical component should be repaired/ rehabilitated or replaced. The decision is based on two factors: First is the‘Age of the bridge’ and the second factor is, the cost of rehabilitation as compared to the cost of replacement. Both these costs are compared for the same type of bridges, with the cost index being the same for the comparison. Also the costs are compared for, per square meter of deck area.
Age of bridge is compared to the cost of repair/ rehabilitation on a graph. This graph basically determines, if the bridge is to be repaired / rehabilitated or replaced. Costs are taken as the average cost of construction of a new bridge in today’s scenario, on per square meter of bridge deck area. Similarly,the total cost of rehabilitation or repair is then converted to cost per square meter of deck area to be used for plotting on the graph.
All bridges, to be repaired / rehabilitated / replaced in a given period of time, are taken together to form a set of bridge. Ranking of the bridge is always assigned from within this set of bridges being compared. Ranking of the bridge is given by ‘RankBrig’. ‘RankBrig’ is evaluated by arranging all bridges as per their Sum of Weightages (WSUM) in ascending order.
WSUM = Cw + Iw
When WSUM is highest for a bridge, it is assigned the RankBrig = 1. For a bridge, which has the lowest WSUM, it is assigned the RankBrig = Last. This type of ranking allows the various rating evaluation and bridge importance to be accounted for, in the decision- making process for deciding which bridge shall be repaired first. Hence, the FRWD – First Repair Worst Damage principle is used here, in a modified form to account for the importance of the bridge.
Various other modules like the Deterioration Rate, Prediction of Balance Life, Estimation of Life Cycle Cost and Optimization of Funds, which are a part of the IBMS.
Objectives of IBMS:
- a) Maintain Bridge Inventory and network in an efficient manner
- b) Guarantee safety of the users for specified risks.
- c) Determine inspection and maintenance needs
- d) Ensure level of service
- e) Predict future needs of funds
- f) Optimize fund utilization
- g) Prioritize asset for maintenance needs
- h) Predict balance service life and optimize its life cycle costs
- i) Provide accurate and real time information of the asset to users and owners
The Government of India constitutes various working groups to review the growth potential and scope of work, which can be done in each 5-Year plan. One such group, is the Working Group on Central Road Sector. They submitted a report in 2011 for their recommendation for the 12th Five-Year Plan (2012- 2017). In that report, the group makes a very strong case for implementation of Bridge Management System, in a timely manner. Writing about bridges, they have stated that ‘a System of maintaining and updating database on bridge inventory needs to be set-up for enabling timely decision making, regarding formulating their maintenance strategies.
In the concluding part they have stated: “Roads are valuable assets and justify preservation and regular maintenance. For a modest erosion of 5%, due to deficiency in maintenance, the loss is much more than the amount required for its preservation. THERE IS NO ECONOMIC SENSE IN LOSING OUR ASSETS.”
Establishment of IBMS ensures the concluding remark is upheld and implemented on nation’s National Highways network. NH network is about 2% of the road network in our country. The way forward is to implement IBMS on all the State Highways and all the major Districts’ roads, so that, at best 50% of road network can be brought under the gambit of IBMS, which will ensure that IBMS is Protecting Indian Bridges.