The need to evaluate a location for preemption often begins with one of the following scenarios although other scenarios may present themselves.

Railroad Investigator identifies a potential need through annual inspections
A railroad or highway authority identifies a concern through inspection or routine maintenance
Roadway or railroad improvements impact the operation of a crossing
Crash Data or near miss reports from rail operator, highway authority, or other witnesses

The TxDOT Rail-Highway Operations Manual requires the District Railroad Coordinator to arrange to have filled out in preparation for the diagnostic inspection. TMUTCD recommends “If a grade crossing is equipped with flashing-light signals and is located 200 feet or less from an intersection or midblock location controlled by a traffic control signal, a pedestrian hybrid beacon, or an emergency-vehicle hybrid beacon, the intersection should be provided with rail preemption in accordance with Section 4F.19 unless otherwise determined by the Diagnostic Team.” Where a crossing is within 200 feet of an intersection or queuing is otherwise expected near the tracks, the District Railroad Coordinator shall require the requesting agency (RRD, railroad, or highway authority; referred to as the Requestor) to complete the following three steps to determine the need for preemption and TxDOT Form 2304 prior to the diagnostic:

Step 1: Measure Available Storage Distance
Step 2: Determine Queue Lengths
Step 3: Determine the need for preemption