The present referencing methods have several shortcomings:
The methods do not conveniently relate to each other. Data collected by one referencing method may not be usable in an application based on another method. If it cannot be conveniently cross-referenced, important data may not be used.
The historical consistency of referenced locations is difficult to maintain. Roadway realignments, repositioning of MRMs, highway renumbering, and transfer of highway ownership are some of the situations that do not allow historical data to be used without a substantial amount of manual review. Changes to the MRM file do not automatically update MRM references in other databases without additional editing and programming.
Not all methods accommodate special circumstances, such as coincident highways, divided highways, realignments, ramps, non-state trunk highways, and off-road attributes.
The current methods do not efficiently support relational databases, which would enhance the Departments capability to interact with other computer systems, such as the pavement management system, geographic information system, the Decision Mapping project and other systems using spatial technologies.
Past research studies have suggested that an location referencing system (LRS) is essential to efficiently and effectively manage transportation data. SDDOTs Historical Data Base Feasibility Study SD90-09 recommended that x,y,z coordinates and date and time be attached to most of the data items retained in the Roadway Environmental Subsystem (RES). SD90-09 also recommended that a distributed relational database would support SDDOTs data and computational requirements.
SDDOT requires a standard location referencing system that will support multiple location referencing methods currently used by the Department. The standard location referencing system must:
unambiguously reference locations on and off roadway networks;
maintain compatibility with SDDOTs present linear and geodetic systems;
allow other state agencies to use the data
accommodate special circumstances
A strategy needs to be developed that outlines the procedural steps necessary to implement the standard linear referencing system. Important to implementing a standard LRS is a review of the hardware and software alternatives with an evaluation of the costs and benefits. The new system must be developed considering SDDOTs current procedures and institutional and fiscal constraints.