There may be a crossing where left turns are allowed towards the tracks but can be ignored in the preemption calculations due to the geometrics and/or operations of the crossing and adjacent intersection. If the following scenarios apply to the subject crossing, the design may omit the calculation of left turns towards the tracks by selecting “No” for Line 28 on TxDOT Form 2304.

At some crossings, the distance between the intersection and the tracks is approximately the design vehicle length (DVL) or greater, meaning there is enough space between the adjacent intersection and the grade crossing to store the design vehicle. The figures below present two potential scenarios with left turns towards the tracks and varying distances between the intersection and the crossing. Figure 3-6 provides an example where left turns towards the tracks should be included in the preemption calculations. Figure 3-7 illustrates a scenario where the designer may ignore left turns towards the tracks and omit them from the preemption calculations.

The designer may also ignore left turns towards the tracks where the left turn towards the tracks is a protect only left turn with sufficient yellow and red time to clear the design vehicle through the intersection.