Linear Referencing System (LRS) for the Caltrans highway network to meet HPMS requirements



Caltrans needed to build a linear reference systems (LRS) to support upcoming federal Highway Performance Monitoring System (HPMS) requirements. They asked Farallon to recommend a plan to pilot development for five counties in the Sacrmento area, to meet the new HPMS standards.

HPMS is a federally mandated inventory system and planning tool designed to assess the nation’s highway system. It is used for apportionment, performance measures, highway statistics, and conditions reporting (which translates directly to funding dollars).


Farallon formulated a series of recommendations for LRS and event calibration, best available source data, and software platforms. Farallon then defined procedures to standardize street names across the core GIS street data and the HPMS event data and then use addresses and road intersection points to automatically identify HPMS event locations along the street network. Manual procedures were defined for HPMS events where tolerance standards were exceeded.

Caltrans took this HPMS project as an opportunity to ask Farallon to devise a statewide geospatial referencing system that not only would accommodate HPMS events, but could be reference-system agnostic to allow disparate systems to reference the network in differing ways.  Farallon recommended an approach for a flexible LRS solution that could be used as a basis for Caltrans to extend this HPMS work beyond the pilot area and to accommodate future projects.

Screenshots & Videos

Automatic addresses and intersection points identification of HPMS event locations along the street network

Automatic addresses and intersection points identification of HPMS event locations along the street network