Signal and interlocking plan at Brantford, Canadian National Railways.
C. H. Tillett, Signal Engineer, Central Region, Canadian Nationa
Brantford, Ont., is on the Canadian National double track main line from Hamilton to London (Dundas Subdivision, London Division, Southwestern Ontario District), 24.33 miles from Hamilton, and 54.99 miles from London, and two branch lines join the main line there, one, the Burford Subdivision, Stratford Division line, from the southwest, from Tillsonburg; and the other, the Dunnville Subdivision, Stratford Division line, from the southeast, from Buffalo and Bridgeburg. The junction with the main line is made so that trains from both Buffalo and Tillsonburg must run for a short distance against the current of traffic on the eastbound track of the main line before passing to the westbound track or into the yard. Formerly, switches were looked after by a switch-tender, who also furnished protection for movements against the current of traffic on the eastbound main line track. Eastbound trains passed through at restricted speed, enforced by a permanent slow order. Crossovers in the main line tracks are located near 2 street crossing, at which crossing gates are operated from an elevated grade tower. It was through that better protection could be afforded to both railway and streets, and that considerable economy could be effected, if the duties of the 2 sets of men were combined, by operating the switches from the same point that the gates were operated from.
Signal and interlocking installation at Brantford. Left, gate tower looking east, showing mounting of eastbound signals. Center, desk lever interlocking machine. Right, light signals at junction switches.
Room was not available on the right of way for the erection of a standard interlocking tower, not was additional right of way available, on account of a street on one side and a cemetery on the other. Therefore, the existing gate tower, which was 6×12 ft., was enlarged by making an 18 in. extension of the field side, for the accommodation of a relay battery case, and a stove. A bay window was added on the track side, to form a shelf 2×6 ft. upon which to mount 8 units of General Railway Signal interlocked desk circuit controllers, which serve as the interlocking machine. A chase for the wire was built from the underside of this shelf, underneath the floor to the relay case, joining with the vertical chase so that wires can be run in all directions. The circuit controllers contain sufficient indicators to furnish all the information required to operate the plant. The manipulation chart, time releases and push buttons, for clearing the call-on signals, are mounted above the machine, and a space on the shelf at the ends is sufficient to provide for switches for operating the crossing gates electrically.
Signal and interlocking installation at Brantford. Layout of track and signals.
One lever is used for each of the 2 cross-overs, and one each for the 2 junction switches. The levers control normal and reverse relays at the switches. Switch circuits are carried through the relay and lever contacts, so that the normal control wire acts as the reverse indication wire, and vice versa. The locking sectors of the switch levers allow free movement between indicating positions, but the levers cannot be placed in the extreme positions to release the mechanical locking until the switches operated from them are locked in a position corresponding to the position of the lever. For indicating purposes, a battery at the switches is used, while the switch control relays are energized from a central control battery in the tower. To simplify the selection of signal circuits over crossovers, SS relays in the tower, in multiple with the indication lock, provide the necessary contacts. Selection of the signal circuits over the junction switches is done in the switch machine direct.
Signal levers are normal in the center position, the extreme right or left position putting current from the tower battery on the signal control wire to clear the signals, and can only be moved to the indicating position, when being restored to normal, when all the signals controlled by that position of the lever have assumed the stop indication. This indication current comes from the battery at the signals through all the signals in series. The switches are operated by G.R.S. model 5 switch machines from two 24-volt batteries, one at each group of switches. A hand crank is placed in a box at each battery location, and locked with a switch lock. The removal of a crank from the box cuts off the current from the operating battery to the group of switches, so that when the switches are being operated from the ground, for emergency or test, the possibility of movement from the tower is removed. Signals are Hall searchlight type, and 10 watt lamps on the home and dwarf signals burn continuously at 10 volts a.c. Reserve lighting source is provided by 1o-volt indication batteries, which automatically take the load if the a.c. line fails. The top signals of the 3 high home signals on the double track are semi-automatic, and form part of the automatic signal system of the double track line. Movement into an occupied block is made by the bottom signal, which can be cleared by a push button after the signal level is in proper position. Bottom signals also govern on diverging routes, and when the route is so set, the reversal of the signal lever will clear the bottom signal without the use of the push button.
Exide KXH-7 storage batteries are used as the source of energy throughout the installation, the charging being done by G.E. 60-cycle Magnar chargers. Wire, conforming to A.R.A. specifications, was furnished by Northern Electric Co. The plans were made in the office of the Signal Engineer, Central Region, and construction was carried out by Southwestern Ontario District forces, under direction of W. H. Patton, Superintendent of Signals, and J. J. Killingsworth, Supervisor of Signals, Stratford Division. The operation of the plant is found to be fast enough to meet traffic conditions, as the full movement of the switch levers is obtained in about 12 seconds, average time. The same type of plant has been built at Lynden Jct., about 8 miles east of Brantford, where a new Y has been installed. At that point, a 7-unit circuit controller operates 5 switches and 15 signals. In this plant the operation is effected from the tower of the existing mechanical interlocking plant, which operates the old junction forming the third end of the Y. The nearest switch of the new Y is 3,300 ft., and the furthest 3,900 ft., from the machine.