Condition Assessment Model

In order to ensure the implementation of the proposed methodology, it is imperative to take full advantage of the bridge inspection data collected in the bridge inventory database of different highway agencies. In general, highway bridge decks (and other bridge components) are inspected every two years on average (FHWA 1995; MTO 1989). The inspector rates the condition of the bridge deck and assigns condition ratings for the deck. This condition rating consists of mapping the level of observed damage in the structure during visual inspections and non-destructive evaluation (or predicted using empirical or statistical methods) onto a discrete (1 to 9, 1 to 7, or 1 to 5) rating scale. Concrete bridge decks are inspected for cracking, spalling, delamination, potholing, rust staining, scaling, reinforcement corrosion, chloride contamination, and partial or full depth failures. In this paper, the condition rating (CR) of concrete bridge decks is based on the following seven – state rating scale, which reflects the different damage states associated with chloride-induced corrosion and is adapted from existing different condition assessment systems (Golabi and Shepard 1997; FHWA 1995; MTO 1989; Morcous et al. 2003). Table 1 provides a summary description of the adopted condition rating system.

Table 1. Condition rating system for concrete bridge decks

Condition Rating (CR)

Description

1

Excellent condition: no contamination; no corrosion; no repaired area.

2

Very good condition: minor cracks, no spalls or delaminations; chloride contaminated or repaired areas < 2% (of total deck area).

3

Satisfactory condition: spalls or delaminations < 2%; cracked, corroded, contaminated, or repaired area <10%.

4

Fair condition: spalls or delaminations < 5%; cracked, corroded, contaminated, or repaired area <20%.

5

Poor condition: spalls or delaminations < 10%; cracked, corroded, contaminated, or repaired area <25%.

6

Critical condition: spalls or delaminations < 15%; cracked, corroded, contaminated, or repaired area > 25%.

7

Failed condition (total loss of serviceability or functionality): extensive spalling, delamination, repaired areas > 30%; maintenance required.

Such a condition assessment system is very practical and cost-effective (in terms of inspection/evaluation costs) for the long – and short-term analysis of maintenance needs for a network of hundreds or thousands of structures, which is the case for many highway agencies. However, for safety-critical elements and for high-risk structures, a detailed and a more rigorous condition assessment may be required.