Existing and proposed railroad warning equipment, including the railroad gate mechanisms, cantilevers, flashers, railroad signal house, grade crossing surface, and all relevant offsets (centerline of track, edge of roadway, etc.)

Existing and proposed traffic signal equipment, including the traffic signal poles, signal head configurations, traffic signal cabinet, traffic signal controller type and software used, and railroad preemption interface

Correct timing including equipment response time, advance preemption time, clearance time, minimum time, and buffer time. Any traffic signal timings shown shall match timings in preemption form ( )

Phasing diagram for normal operations

Phasing diagram for preemption operations specifying the right-of-way transfer time, track clearance phases, dwell/hold/limited service phases, and exit/return phases

Railroad signal interconnect cable wiring diagram – providing details on which railroad relays are being proposed

Details on how the various railroad relays affect traffic signal operations

Completed Railroad Interconnection Worksheet in Appendix A (See Chapter 4 for details)

Adequate motorist visibility of both highway traffic signal heads and railroad signal equipment at all times

Battery back-up supply for traffic signal system

Per TMUTCD Section 4F.19, “traffic signals with railroad preemption or coordinated with flashing-light signal systems should be provided with a back-up power supply”.
In the event of a power outage or another interference, the battery back-up supply will enable the traffic signal to continue running properly and transitioning to preemption operations safely until any issues are resolved. Typically, the battery back-up supply is installed as a stand-alone piece of equipment, but it may also be side-mounted on the traffic signal cabinet. When designing at interconnected crossings, there is typically a variety of traffic signal equipment, railroad warning equipment, and signage that must be installed within close proximity with one another. Designers should be aware of and be able to accommodate the following design constraints:

Traffic Signal Head Visibility – The roadway needs to be designed such that all the necessary signage, traffic signals, and railroad warning devices are visible to the motorist at an adequate distance to allow time for them to perceive and react safely. It is important to note that from a motorist’s point of view on the road, it can be difficult to perceive a large quantity of indications while also reacting quickly without compromising safety. This issue is magnified when warning flashers, traffic signals, and signs are placed in such a way that they may potentially block one another. In order to provide adequate visibility, designers should denote vertical mounting heights and horizontal offsets for all appropriate traffic control devices in the plans. All equipment locations and construction notes on the design plans should be detailed enough to ensure that the contractor can install all equipment without any visibility conflicts. This may lead to higher/lower mounting heights, larger offsets, and other placement variations when designing near grade crossings.

For visibility-limited traffic signal heads, the cutoff line at which motorists can fully view the signal heads should be noted on the plans so that contractors are aware of how the signal heads need to be programmed and/or adjusted.

Above and Underground Utilities – Designers should note the presence of any existing utilities, both above and below ground, that may impact any proposed improvements at the grade crossing. Designers shall coordinate with the railroad authority in the event that utility work must take place within the railroad right-of-way and follow their standard practice and safety and right of entry requirements accordingly.

Pedestrian Path – the pedestrian path of travel should be designed to follow ADA standards and remain clear of any railroad warning devices and/or traffic signal equipment at all times. Pedestrian approaches should direct pedestrians around the back of railroad gate mechanisms such that they may safely exit the grade crossing during a preemption event without being restricted by the descending railroad gate arms.