Case Study: Developing a Surface Condition Indicator from Laser Crack Measuring System Data for Pavement Asset Management

The Saskatchewan Ministry of Highways and Infrastructure (SMHI) adopted Laser Crack Measuring
System (LCMS) technology for collecting road condition data in 2016. LCMS data has replaced a visual assessment method for identifying cracking and other surface distresses. This paper discusses the methodology used to determine type, severity, extent and aggregation of LCMS distress data. To better analyze the data, SMHI developed the Surface Condition Indicator (SCI) to support asset management decision making for setting performance measures, optimize budgets, and identify pavement preservation candidates.

The paper covers:
• The use of LCMS generated crack maps and a Bayesian sorting methodology
to develop severity ranges for pavement distresses.
• The methodology used to identify the type and severity of LCMS measured
distresses that map to treatment triggers for rejuvenating fog seals (CRF™ and
Reclamite™), graded aggregate seal coat, chip seal, fiber‐reinforced chip seal,
microsurfacing rut fill with a seal coat cape, and functional repaving.
• The methodology for setting the SCI threshold values (Good to Fair and Fair to
Poor).
• The development of SCI formulas for Asphalt Concrete and Granular
Pavements.
• The process of calibrating SCI values with field observations and “blind”
testing the SCI numbers in the field to confirm results for the SCI metric.
• The benefits of adopting the SCI for finding good pavement preservation
candidates and ruling out locations that are too late for fog or seal coat
treatments.
• The benefits of adopting the SCI for setting performance measures and
communicating trade‐offs in investing for pavement preservation projects.

SMHI’s SCI values range from 0 through 100+ in a progression that reflects the amount and severity of pickouts and cracking that develops as pavements age. SCI60 values are categorized as good, fair or poor. Pavement segments with fair SCI60 are light treatment preservation candidates. Pavement segments in the poor category are too late for a light preservation treatment. SCI60 values over 45 require a heavy preservation treatment.