HPMS Base Thickness

The Idaho Transportation Department's (ITD) Roads and Highways Road Network Linear Referencing System (LRS) HPMS base thickness event polyline feature class represents the thickness of the lowest pavement layer, commonly referred to as the base course, beneath the surface layer of the roadway. This information is collected and maintained as part of the HPMS inventory to support structural design, performance modeling, and pavement condition assessment. The base thickness attribute indicates the compacted depth of granular, stabilized, or treated material placed directly on the subgrade to provide load distribution and structural support. Thickness values are typically expressed in inches and derived from design plans, as built documentation, or pavement management system records. This dataset is used by engineers, planners, and researchers for evaluating pavement structure adequacy, forecasting maintenance needs, and analyzing the relationship between pavement design and performance. It is updated annually as part of ITD’s Highway Performance Monitoring System (HPMS) submittal process to the Federal Highway Administration (FHWA) and reflects current data available from pavement inventory systems and design records. This layer is an export from Roads and Highways that represents only the active records within the LRS. These are current “working” records. For the static, published data, please see the records stored at: https://www.fhwa.dot.gov/policyinformation/hpms.cfm This content item is a sub-layer of the Highway Performance Monitoring System (HPMS) authoritative feature layer. Metadata