Performance Measures for Enhanced Bridge Management

Abstract

The establishment of clear performance measures can help agencies to assess the extent to which a bridge program, project, or policy has succeeded or is expected to succeed in achieving intended goals and objectives. Chosen properly, a set of performance measures can adequately describe the full consequences of competing bridge actions and thereby help identify the most desirable. Typical bridge management goals and performance measures considered by bridge decision makers are identified. The research summarizes the best practices in quantifying a number of performance measures related to these goals. There is discussion of desirable properties not only of individual performance measures but also of any set of performance measures intended for any particular bridge evaluation problem.

State-Of-Research on Performance Indicators for Bridge Quality Control and Management

“…While operational technical PIs are commonly used in practice by engineers of road agencies dealing with large stocks of bridges, research technical PIs are more refined metrics developed by academics, and whose practical application is still ongoing. Patidar et al (1991) first gave a clear definition of technical PI in BMS applications, highlighting how it should have the following properties:…”

“…• Appropriateness: PI "should be an adequate reflection of at least one agency goal or objective" (Patidar et al, 1991); • Comprehensible and defensible: PI "should be clear, simple, and concise in its definition" (Patidar et al, 1991) as well as in its method of computation; • Comprehensive: PI levels "should cover the full range of possible consequences" (Patidar et al, 1991); • Dimensionality: PI "should be able to capture the required level of each dimension associated with the decision-making problem, and it should be comparable across different time periods or geographic regions" (Patidar et al, 1991); • Measurability: PI should be objectively measured;…”

“…• Predictable: it "should be possible to reliably determine future PI levels" (Patidar et al, 1991) like with the use of forecasting models; • Realistic and operational: PI should be reliably measured without excessive effort or time; • Unambiguous: PIs should be clearly defined and their metric should be directly related to the consequences.…”

“…• Visual Pattern Elements: this PI describes "how well the bridge fits into the overall landscape on the basis of primary visual attributes" (Patidar et al, 1991) of objects like color, form, line, texture; • Scale Contrast: this PI describes "the extent to which a bridge blends into its environment on the basis of its relative size with respect to those of other features in its environment" (Patidar et al, 1991); • Spatial Dominance: this PI is similar to the previous, "but pertains to a larger dimension; is the extent to which the bridge elements would be dominant in views of larger landscape and cityscape" (Patidar et al, 1991); • Diversity: this PI describes "a function of the frequency, variety, and intermixing of the visual pattern elements of the bridge with its setting. Also termed as setting contrast (the extent to which project's visual pattern elements contrast with or blends in with its existing natural or man-made background)" Patidar et al (1991); • Continuity: this PI evaluates "the uninterrupted flow of pattern elements in a landscape and the maintenance of visual relationships between landscape components that are immediately connected or related" (Patidar et al, 1991);…”

“…• Variety: this PI estimates "the richness/diversity of physical objects and interrelationships within the landscape" (Patidar et al, 1991); • Visual quality: this PI rates "the excellence of the viewing experience. Visual quality may be assessed using one of several approaches, e.g., via using opinion surveys of viewers, or judgments of visual quality metrics like vividness, intactness, unity" (Patidar et al, 1991).…”