Location Reference System
The Location Reference System (LRS) provides a framework for which all Roadway Management System (RMS) data can be tied to true roadway locations. LRS is divided into the following two types of operational programs:
- The LRS Quality Commitment (QC) program, which entails field testing of approximately 2,200 miles annually (5% of each county’s state highway system). The QC program has been in place since 1990. The goal is to maintain at least 95% accuracy between the RMS and the actual field locations of highway features recorded in the system.
- The LRS Quality Assurance (QA) program entails field testing of all state owned roads within a 5 year cycle. The current goal is to test and process 20% of all state roads per year. After the roads are tested and processed the results are sent to each engineering district where the location referencing data is updated in RMS as required.
PennDOT’s LRS vehicles are manufactured by International Cybernetics Corporation, of Largo, Florida. Roadway Inventory and Testing Unit (RITU) maintains 4 LRS testing vehicles. These devices are vans equipped with an on-board computer that consists of an IBM-PC compatible computer System Unit with associated Super VGA monitor, compact keyboard, printer, customized event boards and RS-232C Serial Interface. A data measurement subsystem installed in the system unit provides interfaces to a wheel mounted distance transducer. All newer units are driven by Windows compatible software.
The system unit accepts a downloaded RMS file containing all roadway information as an input database for verification and outputs an RMS file containing all feature information, segment and offset values, as well as any comments made during verification. Vehicle location and roadway features are displayed on the computer screen in a Straight Line Diagram (SLD) format, and the software accepts operator inputs verifying or modifying roadway feature locations. Collection and display is in real time including on-board analysis and instant recall of previously verified features.
The system is capable of performing verification at highway speeds, but usually test speeds are less than 25 mph to ensure accuracy. State routes can be tested in increasing or decreasing segment order and test sections may begin on a segment beginning, ending, or any permanent landmark feature.
Two persons are needed to perform testing, a driver and an operator. Typically, the operator is a permanent Roadway Programs Specialist or Technician 2, and the driver is a temporary Roadway Programs Technician 1. The QC program field testing is typically performed during the months of April through November, and the QA program is performed year round.
LRS QC DATA
The information that is verified and/or modified as part of the LRS QC program is broken down into four categories:
- State Route Length: The total length of a state route measured in feet by summing the segment lengths of all undivided highways and the longest side of divided highways.
- Segment Length: The total length of a segment in feet from the beginning offset to the ending offset.
- Intersecting Feature: The county, state route, segment, and offset value of the at grade intersection, or the bridge identifier, and the intersection type code.
- Segment Marker: Marks the beginning of a segment. For undivided roads this includes both the ahead and back signs.
Accurate segment markers are of obvious significance. Signing is important to many people within the Department (including Pavement Testing and Distress Surveys, Design, Construction, Maintenance, Highway Occupancy Permits, Roadway Posting and Bonding, Tort Liability, Turnbacks, Planning and Programming, Traffic, Municipal Services, Utilities, Right of Way, Crash review and Analysis, and Emergency Management) and customers outside the Department (including the Federal Highway Administration, County 911 programs, State & Local Police, Townships, Local Emergency Management, Consultants, Delivery Services (UPS, Fed Ex, etc.), Fire Departments, and Utility Companies). When segment marker signs are missing or improperly placed, the information reported may not be tied to the proper location.