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Ontario Structure Inspection Manual

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Ontario Structure Inspection Manual

Ontario Structure Inspection Manual

The Ontario Structure Inspection Manual has been used for bridge inspections in Ontario since 1985. The manual underwent significant modifications in the year 2000 (OSIM, 2008). This FAQ provides general definitions and terminology used in the OSIM 2008.


A substructure unit which supports the end of the structure and retains the approach fill.

Auxiliary Components

Any component which does not share in the load carrying capacity of the structure.

Biennial Structure Inspection

An inspection performed in every second calendar year to assess the condition of the structure, in accordance with the methodology described in OSIM.


A structure which provides a roadway or walkway for the passage of vehicles, pedestrians or cyclists across an obstruction, gap or facility and is greater than or equal to 3 m in span.


The generic term for paint, lacquer, enamel, sealers, galvanizing, metallizing, etc.

Concrete Deck Condition Survey

A detailed inspection of a concrete deck in accordance with The Structure Rehabilitation Manual.


An identifiable, unwanted condition that was not part of the original intent of design.

Detailed Visual Inspection

An element by element visual assessment of material defects, performance deficiencies and maintenance needs of a structure.


A defect that has occurred over a period of time.


The individual parts of a structure defined for inspection purposes. Several bridge components may be grouped together to form one bridge element for inspection purposes


The determination of the load carrying capacity of structures in accordance with the requirements of the Canadian Highway Bridge Design Code.

Floor Beam

Transverse beams that span between trusses, arches or girders and transmit loads from the deck and stringers to the trusses, arches or girders.


A common and public thoroughfare including street, avenue, parkway, driveway, square, place, bridge, designed and intended for, or used by, the general public for passage of vehicles, pedestrians or animals.


Any action which is aimed at preventing the development of defects or preventing deterioration of a structure or its components.


Any modification, alteration, retrofitting or improvement to a structure subsystem or to the structure which is aimed at correcting existing defects or deficiencies.


Any modification, alteration, retrofitting or improvement to a component of the structure which is aimed at correcting existing defects or deficiencies.


The horizontal distance between adjacent supports of the superstructure of a bridge, or the longest horizontal dimension of the cross-section of a culvert or tunnel taken perpendicular to the walls.

Suspected Performance Deficiency

A Suspected Performance Deficiency should be recorded during an inspection, if an element’s ability to perform its intended function is in question, and one or more performance defects exist.

Culvert (Structural)

A Structure that forms an opening through soil and;

  • Has a span of 3 metres or more (e.g. S in the diagrams below), or


  • Has the sum of the individual spans of 3 metres or more, for adjacent multiple cell culverts (e.g. a+b+c in the diagrams below),or

Culvert (b) OSIM

  • Has the sum of the individual spans of 3 metres or more, for multiple cell culverts (each with spans at least 2m) separated by soil (a width not more than the span of smallest individual cell) (e.g. a+b+c in the diagrams below, where a, b, and c are all ≥ 2.0m and d and e are both ≤ the minimum of a, b, and c), or


  • Has been designated by the Owner as qualifying as a culvert.


Diagonals are component which spans between the top and bottom chord of a truss or arch in a diagonal direction.


A defect produced by loading.


An element’s exposure to salt spray:

  • Benign – Not exposed (e.g. River Pier)
  • Moderate – Exposed but element protected (e.g. Asphalt covered and waterproofed deck)
  • Severe – Exposed and element not protected (e.g. Exposed concrete deck, Barrier Wall)

Lateral Bracing

Bracing which lies in the plane of the top or bottom chords or flanges and provides lateral stability and resistance to wind loads.

Portal Bracing

Overhead bracing at the ends of a through truss or arch and provides lateral stability and shear transfer between trusses.

Primary Components

The main load carrying components of the structure.

Retaining Wall

Any structure that holds back fill and is not connected to a bridge.

Secondary Components

Any component which helps to distribute loads to primary components, or carries wind loads, or stabilizes primary components.

What is Low Strain Pile Integrity Test ?

Pile Integrity Tes(PIT), or “low strain impact integrity testing of deep foundation” is a widely used non-destructive test method for the evaluation of pile quality, and integrity. The test can also be used to estimate the unknown length of existing piles and foundations. In the low strain impact integrity testing, the response of the pile to an impact on the head of the pile shaft is determined by a high precision transducer mounted on the pile head. The transducer can either be an accelerator, or a velocity sensor. The test standard allows two different procedures to obtain acceleration and force information:  1) Pulse-Echo Method (PEM) or Sonic-Echo (SE) and 2) The Transient Response or Impulse-Response (IR).

How Many Impact is required for low strain integrity testing?

The general rule for the minimum number of impacts for low strain integrity testing is: The more, the better (assuming that each signal is collected properly). Increasing the number of impacts, and using the average signal will reduce the effect of background noise, and helps enhance repeatable parts of the signal, which will improve data visualization and makes interpretation much easier.

For circular (Diameter less than 500 mm) and rectangular cross sections, place the sensor near the center of the pile and strike several times around the pile head (i.e. 10 impacts).

For piles with larger diameter (i.e. Diameter > 500 mm) additional locations should be considered to obtain useful integrity information about the pile. Choose a minimum of 3 different locations. Collect adequate number of impacts for each location.

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