Figure 8D-1. Composite Drawing of Active Traffic Control Devices for Highway-Rail Grade Crossings Showing Clearances
This figure shows a composite drawing of active traffic control devices for highway-rail grade crossings showing clearances. It illustrates the location and clearance dimensions of a traffic control assembly with signal lights and a gate at an at-grade crossing.
The figure shows a post-mounted flashing-light signal with two red lights shown mounted in a horizontal line, two red flashing-light signals shown mounted on an overhead structure, and a red and white striped automatic gate assembly with three red lights. The gate is also shown in the horizontal position to the left of the post, extending across the pavement. A white Railroad Crossing crossbuck sign and inverted T-shaped sign with the words "2 TRACKS" are also shown mounted on the post above the post-mounted lights.
On the overhead light structure, the distance from the center of the mounting post to the center of the flashing-light signal support is shown as a length as specified. The distance from the crown of the roadway to the bottom of the background disks behind the signal light lenses is shown as a dimensioned distance of 5.2 m (17 ft) MIN. CLEARANCE ABOVE CROWN OF ROADWAY. The width of each lens is shown as a dimension of 200 mm (8 in) to 300 mm (12 in).
The location of the traffic control assembly when the gate is in an upright position is shown as a dimensioned distance of 0.6 m (2 ft) from the edge of the background of the signal light lens or part nearest the roadway to the edge of the roadway. A note states: "For locating this reference line at other than curb section installation, see Section 8D.01."
The base of the post assembly is shown as a dimension of 100 mm (4 in) MAX ABOVE GROUND LEVEL. The distance from the center of the mounting post to the counterweight end of the gate is shown as a dimensioned distance of 1.3 m (4.25 ft) MAX. The distance from the outside edge of the mounting post to the top edge of the counterweight of the gate is shown as a dimensioned distance of 635 mm (25.4 in) MAX. The distance from the crown of the roadway to the bottom of the overhead lights is shown as a dimensioned distance of 2.3 m (7.5 ft) MIN. to 2.8 m (9.5 ft) MAX.
Two red signal lights with background disks behind the lenses are shown mounted on the traffic control post. The distance between the centers of the two lights is shown as a dimensioned distance of 750 mm (30 in). The distance from the center of the mounting post to the center of each light is shown as a dimensioned distance of 375 mm (15 in).
A red and white gate is shown attached to the post. The gate arm is shown with 45-degree diagonal alternating red and white retroreflectorized stripes. The gate arm is shown with three red lights on it at varying distances noted as A, B, and C. A note states: "Dimension A-B-C and length as appropriate for approaching traffic." The distance from the crown of the roadway to the bottom of the gate when horizontal is shown as a dimensioned distance of 1.1 m (3.5 ft) MIN. to 1.4 m (4.5 ft) MAX. A note states: "Where gates are located in the median, additional median width may be required to provide the minimum clearance for the counterweight supports."