Bridge connects the road to overcome any type of obstruction like nala, river, valley, canal, roads, railway truck, etc. The bridge structures are playing the main role in our transport network. The cost of a road construction project depends on how many bridge structures will be constructed. So, after the completion of construction work we need to maintain the roads and bridges.

What's the Importance of Bridge Inspection, Different Types of Bridge Inspection, Bridge Inspection Guidelines, and Bridge Inspection Procedures, etc. are described here.

Picture 1: Bridge Inspection With MBIU

Importance of Bridge Inspection || Type of Bridge Inspections || Bridge Inspection Procedure

Importance of Bridge Inspection:

The main purpose of bridge inspection is to ensure the safety of bridge and enhance the bridge serviceability. In bridge inspection, we have to check all members of bridge and rest of elements which plays an important role on bridge like protection of bridge, safety measures things etc. Bridge inspection allows static problems and engineers to identify all kind of minor defects in bridges before they develop into major issues. Some major issues like major cracks on elements of bridge, some kind of distresses on elements etc. For Bridge inspection you need to know about all kind of distresses which can act on bridge or can play a major role to collapse the bridge. It is mandatory to know about all the things which are discussed in our article keeps on your mind during inspection of bridges.

Duration of Bridge Inspection:

We have to deal with all the necessary problems which can act directly on bridge or plays an important role indirectly on bridge. It is mandatory to know about the function of all bridge’s elements which can help to know about the reason of failure of that particular element of bridge. The gap between two inspections has about 6 months during bridge inspection we have to note down all the distresses which are present on bridge or can play a vital role to collapse the bridge and after collecting all the data from site we will make report. After every 6 months need to check the distressed elements and rest of the bridge and make new bridge inspection report (pre-monsoon and after monsoon).

Study The Available Design Data and Drawing:

Before going to inspect the bridges, we collect and study of all design, GAD, detailed working drawing, as-built drawing, survey reports, previous inspection reports, etc. related with the concerned bridge(s) from the Authority.

Mobile Bridge Inspection Unit Team:

Mobile Bridge Inspection Unit Team consists of 1 Team leader cum bridge Engineert+1 bridge Engineer+2 Assistant Bridge Engineers.

Types of Bridge Inspection:

There are three Types of Bridge Inspection. Generally, the criteria of bridge inspection lie on below-mentioned points which are:

1. General Inspection or Routine Inspection.
2. Detailed Birdge Inspection.
3.Special Bridge Inspection.

Now we need to discuss about above-mentioned types for bridge inspection to know about these inspections in detail.

1. General inspection or Routine Inspection:

Visual or General inspection is this kind of inspection that will give us regular updates about the bridge. In routine or regular inspection, we check drainage spouts, wearing course of the bridge, any vegetation developed on a bridge that will be affecting a bridge, excessive settlement or tilt, etc. So these kinds of problems can be solved easily if routine inspection is done on time to time. We inspect 6-7 bridges per day in visual inspection.

Make a shortlist of distressed and critical condition bridges to inspect these bridges thoroughly with the help of the Mobile Bridge Inspection Unit (MBIU).

2. Detailed Inspection of Identified Distressed Bridges Needing MBIU:

After identifying all distressed and critical condition bridges, we move to inspect these bridges thoroughly with the help of the Mobile Bridge Inspection Unit (MBIU). 2 to 3 number of bridges per day can be inspected in detail.

We check the following members

Super structural members (girders, deck, cables, articulation, bearings, pedestals, expansion joints, wearing coat, drainage spouts and vent hole, railing/crash barrier, footpath, any damages due to presence of utility).
Substructure (abutment, piers, return wall/wing wall, etc.).
Bridge foundation
Approach structure. (Approach slab and guard stones).

The objective of this inspection is to analyse the results of the condition survey and to make a structural assessment through detailed investigation in order to enable the Authority to know:

i) Whether there is a risk of failure of the damaged structure

ii) Whether damages are likely to propagate further with time

iii) Whether or not an economically effective repair plan can limit or contain the

damages and enhance the effective service life of a structure

iv) Degree of urgency required in implementing repair

v) To ascertain load carrying capacity

vi) Whether total replacement will be required in case the damages are found to be too extensive or partial replacement and repair based on the severity of localized damage.

Figure-2: Bridge Inspection With MBIU (Mobile Bridge Inspection Unit)

First of all, you need to know about MBIU. MBIU is known as mobile bridge inspection unit, is a bridge inspection machine, it has 3 platforms first one is moving in the vertical direction or can rotate up to 180⁰and length of this platform is 3 meters, the second one is used for horizontal rotation and it also rotates up to 180⁰ length of this platform is 3 meterand the last one is an additional platform which has used when the width of the bridge is more than 3 meter. This machine has a stabilizer that reduces the speed of the vehicle and maintains the proper stability of this inspection instrument.

The main function of MBIU provides you to see the kind of elements of the bridge which is not seen properly under the bridge with the help of this bridge inspection machine we can easily inspect these elements such as bearings, deck of the bridge, abutments, piers, girders, etc.

First of all, you have to collect the data from the site and authorized offices to make a bridge inventory report.

Bridge Inventory Format is prepared as per IRC SP 35 | IRC SP 18

The following steps have to be followed when you inspect a bridge with the help of MBIU:

(I) First of all, you have to visit the location of the bridge

(II) Then you have to open your open MBIU

(III) When this instrument opens properly then check the deck of bridge-like any cracks (hairline cracks, major cracks), spalling, leaching, water stains, honeycomb, etc.

(IV) If the bridge is pre-stressed then check girders like sheathing and tendons, cracks (hairline cracks, major cracks) on girders, honeycomb on girders, etc.

(V) Check bearings and pedestals

(VI) Check drainage spouts which clogged or open, projected or not projected, connected with down take pipes or not, etc.

(VII) Check abutments like honeycomb on abutment face or cap, cracks on the abutment, leaching, water stains, etc.

(VIII) Check piers like honeycomb on abutment face or cap, cracks on the abutment, leaching, water stains, etc.

(IX) Check wearing course of bridge-like cracks are present on wearing course or not, rutting, reveling, potholes, roughness, bulging, unevenness, bleeding, bumping, water ponding due to improper slope, etc.

(X) Check pavement surface of approaches like the geometry of approach, cracks are present on wearing course or not, rutting, reveling, potholes, roughness, bulging, unevenness, bleeding, bumping, water ponding due to improper slope, etc.

(XI) Check kerb riser like they are properly aligned or not.

(XII) Check expansion joints of bridge-like silt and debris are present or not, headers are damaged or not, etc.

(XIII)Check the condition of crash barrier/parapet/railing, handrail

(XIV) Check the condition of footpath if provides

(XV) Check utility if provides

Collect all data, defects, defect locations along with proper image and videography and analysed them. After that make a detailed bridge inspection report.

Click here to get the

"Bridge Inspection Report Format"

"Bridge Inspection Report Sample As Per IRC SP 18 And IRC SP 35''

3. Special inspection:

This type of bridge inspection is performed on the need to inspect a bridge in critical conditions. This kind of inspection is performed when the condition of the bridge is going to be very critical or any natural disaster affected on the structure of bridge. This kind of Inspection of bridge has been performed to monitor suspected deficiencies.

Non-Destructive Test On Identified Bridges:

Non-Destructive Testing (NDT) methods are aimed at estimation of strength and other properties; monitoring and assessing corrosion; measuring the crack size and cover; assessing grout quality; detecting defects and identifying relatively more vulnerable areas.

After analysing all collected data and conditions of bridges, make a shortlist for Non-Destructive Test in which bridges, where the concrete strength is in doubt full and distressed condition of the bridge is in aggressive. Non Destructive Test shall be carried out to confirm/ascertain extent and nature of distresses.