Bridges and culverts are important assets of any country’s highway network. Development of extensive highway network has increased the need to maintain the bridges and culverts in good conditions. The value of these assets runs into billions of dollars. Having a digital database of all our bridges can be a game-changing approach. Subject to the consideration of its importance, the government of India has launched Indian Bridge Management System (IBMS). As part of this exercise, all the bridges and culverts are bring given unique numbers – just like the registration numbers for vehicles. Such a plan can address the needs for identifying, documenting, and managing the distressed bridges.
Government constitutes various working groups to review the growth potential and scope of work that can be done in each Five Year Plan. One such group is the Working Group on Central Road Sector. They submitted a report in 2011 with their recommendation for the 12th Five-Year Plan (2012-2017). In that report, they 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. Development of Bridge Management System may be considered to be set up in a time bound manner for this purpose.
They have also outlined the basic reason for the poor maintenance and indicated that maintenance should be removed from the non-plan expenditure and a separate head of account be created in the planned expenditure head different from construction. This way, maintenance can be taken up as needed without getting delayed due to lack of funds. The report also pointed out that the governments do apply ad-hoc cuts in maintenance amounts due to resource constraints.
Relevance of bridge management
Due to the significant role of bridges in transportation networks and in accordance with the limited funding for bridge management, remedial strategies have to be prioritized. Bridges fulfill the idea of connectivity while culverts are meant for drainage and protection from floods. Any negligence and delayed actions in the maintenance of bridges may lead to their degradation, which in turn leads to large future costs. A comprehensive inventory of bridges and culverts on highway networks can provide the state and local public works departments (PWDs) with information necessary to appropriately prioritize the repair and replacement projects.
The ultimate goal of the Bridge Management project is to reduce future roadway closures, hazards, and property damage. The system for prioritizing maintenance work can optimize the cost of repair or redesign. Proper maintenance can also ensure public safety and distress management. Maintenance and retrofitting work of these assets can be planned by considering the socio-economic importance and traffic growth. Such approaches can extend the life span of bridges or culverts, provide a well-structured and well-connected highway network to facilitate faster economic growth.
How to asses culverts and bridges
Assessment methodology can include systems for field inspection, condition rating, and prioritization of maintenance work. A system of prioritization could be based on the ‘importance ‘and ‘condition’ of bridges or culverts. The ‘importance ‘can be assessed based on the relative likelihood and consequences of failure (i.e., risk factors). The ‘condition’ can be assessed using the material, shape, size and traffic conditions associated with each bridge, culvert and the probability of each bridge, culvert falling within a given condition rating. Besides, the assessment methodology can also consider other parameters such as slope, flow condition, grade, approach angle, depth, extend of sediment deposit, bank erosion and predominant vegetation type.
The accuracy of decisions developed by any bridge manager or engineer relies on the accuracy of the condition assessment. To validate the assessment, various parameters such as socio-economic importance can be considered. Some countries use remote sensing technologies to assess and monitor the condition of bridge infrastructure and improve the efficiency of inspection, repair, and rehabilitation efforts. This investigation will build on the existing work that places sensors directly on the bridge structure to assess the condition (i.e., deterioration and damage). This information will then be analyzed by a computer decision support system to develop unique signatures of bridge condition. Monitoring the changes in these unique signatures as a function of time will provide the engineers with information that can be used to prioritize maintenance and repair works.
The Indian Bridge Management System (IBMS)
The Ministry of Road Transport and Highways (MoRTH) took an initiative to implement the Indian Bridge Management System (IBMS). It generates detailed inventory and ratings of all bridges on the annual basis. Such information could help understand the dynamics/rate of deterioration processes and control it as needed. This follows the dual principle: the idiom, “a stitch in time saves nine”, and worst damage first repair (WDFR).
IBMS was conceptualized in August 2014 and the responsibility of developing and implementing it was bestowed on the S&R (Bridge) department of MoRTH. India did not have any system for the management of assets such as bridges or culverts. Therefore, an international tender was floated for the development and implementation of IBMS. Then, IDDC Engineers Mumbai was awarded the work in May 2015.
For field studies, the National Highway Network was divided into 18 packages and empanelled consultants were selected for each package based on an online tender process. Consultants of repute like RITES, Casta Engineering, Aarvee, SN Bhobhe, SA infrastructure, K&J projects, ICT, DruV Consultancy Planning and Infrastructural Development Consultants, MC Consulting, Feedback Infra, etc. were selected to conduct the field studies.
How IBMS works?
The IBMS creates an inventory of and applies a scientific logic to manage all the bridges in our country. The development of IBMS poses its own challenges in the inventory development and condition assessment and structural rating. All the bridges in India need to be given a unique identity number, which is the first step of inventory creation. Then, their precise location details in form of latitude and longitude need to be collected in an automatic mode using the Geographical Positioning System (GPS). Then, the engineering properties of the materials and structural systems of all the bridges or culverts need to be collected. On completion of inventory, the structural component rating can be done using a 0 to 9 scale to define the material or structural conditions of various bridge components.
In addition, the scour rating, waterway adequacy, structural rating and socio-economic parameters need to be assessed. Based on the inventory and ratings codes, IBMS analyses the data and indicates the bridges, which need further investigation (may be using various non-destructive testing (NDT) procedures). The initial inventory and rating codes generates the deterioration process prognosis, which is validated by the NDT procedures. A detailed remedial plan is then defined for each bridge tested, which is based on the standard specifications for repair, rehabilitation and strengthening 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 then the level of deterioration defined by the ratings as defined by rating used in conjunction with the traffic on the bridge and age of bridge. The ranking module of IBMS defines a list of bridge that need to be repaired or retrofitted as per priority and can be taken up based on total funds available with the Ministry. This brings in technical and socio-economic logic to the sequence of bridges to be repaired.
Skill development for implementing BAMP
This is an ongoing continuous process, which requires large scale mobilization of bridge engineers and retrofit experts and engineers. India does not have a system to generate such skilled manpower. The MoRTH is also working under the skill development program to initiate a Certified Bridge Inspectors course and Certified Bridge Retrofit Expert course to ensure that the required manpower is available to sustain the system through its usage. Such skill development shall ensure that the quality and efficiency of work done improves.
Benefits of IBMS
Stakeholders of IBMS include: the government, which owns the bridge and culvert assets, the public, who use the bridges and culverts and the bridge and culvert fraternity that designs, builds and maintain the bridges and culverts. Each stake holder has short term and long term benefits as follows:
The government benefits by the creation of a database of all bridge assets in immediate future (say, 6 months). This is the short term benefit and in the long term it optimizes the utility of funds available for the maintenance and rehabilitation of bridges. The overall efficiency in terms of the performance and longevity of the bridges and culverts in our country is anticipated to improve and thereby reduce the long term economic burden.
The public can be assured that with time the general condition of bridge is being monitored and no major sudden catastrophe could affect the connectivity of their movement. They will assured uninterrupted connectivity, especially as the importance of the bridge increases due to increase in population and traffic on the bridge. Its importance will influence the level of upkeep and promptness of maintenance action.
The bridge fraternity shall benefit from long term studies that generate data, which help to decide on possible systems of design, construction that can be modified based on the data on the behavior of bridges in various environmental conditions. Continuous monitoring brings in the awareness of the concept of application of science and technology to ensure economic methods of maintenance of assets.
All infrastructure assets in India need a proper management system to ensure that they are maintained in proper and scientific manner. Under the leadership of Union Minister Nitin Gadkari, the MoRTH has taken the first step in the correct direction in the case of bridges and culverts. Similar systems can be developed and implemented for other national assets such as ports, dams, heritage monuments, among others. A system of maintaining and updating database on bridge or culvert inventory may enable timely decision making regarding formulating their maintenance strategies.
In the recommendation for the 12th Five year plan on Central Road Sector, the committee had stated “Roads are valuable assets and justify preservation and regular maintenance. A modest erosion of 5% due to deficiency in the maintenance, the loss is much more than the amount required for its preservation. There is no economic sense in losing our assets.” Hence, integrating Bridge Asset Management Plan even by every local body seems essential. Also, the design standards and repairing works of these major assets should be in harmony with the requirement of roads serving the access function. Inclusion of remote sensing and non-destructive testing technologies in the bridge assessment and rating processes may help to optimize the costs in tune with traffic growth.
For this, it is necessary to ensure proper budgeting for subsequent up-gradation and give higher priority than new construction. Improved and regular assessments allow for better allocation of the limited financial and personnel resources towards repair and maintenance efforts in order to extend the service life and enhance the safety of bridge assets and its users at minimal costs.
The author is head of Indian Bridge Management System (IBMS) and Director at IDDC Engineers