Major Safety Upgrade Automatic Block Signaling On Great

Major Safety Upgrade Automatic Block Signaling On Great Northern Railway 1

Technical Details 23 detected blocks (current detection) 32 Signals (3 -light and 3 -3 -light) Position feedback from powered turnouts ABS signaling implemented in JMRI with NS-2008 signal rules Detection and signal control done with LCC modules from RR Cir. Kits • Design, procurement, and installation done in 5 weeks • • • 2

Introduction to Signaling • Modern railroads use Speed Signaling where the Lights or Light Pattern indicates speed train is to use after passing the signal. • Speed Terminology – Normal local track speed – Limited 45 mph switches & interlocking – Medium 30 mph switches & interlocking – Slow 15 – 20 mph switches & interlocking – Restricting 15 mph (yards) 3

Terminology • Indication – The message a signal is sending such as Clear, Approach, Stop, or one of many other speed related messages. • Aspect – One of a series of allowed options for the visual pattern that a signal mast can display such as green for a single head or green over red for Clear for a double head. 4

Single Head Signals Next three blocks are unoccupied Block after Next is occupied Indication: Proceed prepared to stop at the next Block. Trains exceeding medium speed must at once reduce to that speed. Next block is occupied Second Block after Next is occupied Indication: Proceed prepared to stop at the second signal. Trains exceeding Limited Speed must begin reduction to Limited Speed as soon as engine passes the signal. 5

GN Double Head Signals - 1 Rule N 282 -A: Advance Approach Indication: Proceed prepared to stop at the second signal. Trains exceeding Limited Speed must begin reduction to Limited Speed as soon as engine passes the Advance Approach signal. Rule N 284: Approach Slow Indication: Proceed, approaching next signal at Slow Speed. Trains exceeding Medium Speed must at once reduce to that speed. 6

GN Double Head Signals - 2 Rule N 283: Medium Clear Indication: Proceed at Medium Speed until entire train clears all interlocking, controlled point or spring switches; then proceed at authorized speed. Rule N 290: Restricting Indication: Proceed at Slow Speed until entire train clears all interlocking, controlled point or spring switches, then proceed at authorized speed. Rule N 281 -C: Limited Clear Indication: Proceed at Limited Speed until entire train clears all interlocking, controlled point or spring switches; then proceed at authorized speed. 7

Hardware 8

Hardware • 2 Tower LCC Parallel 16 channel I/O Boards – 3 BOD-8 block detector boards – 1 digital I/O fan-out board for switch positions • 11 Signal LCC 4 head signal controllers – 10 double head signals – 22 single head signals • 2 LCC bus power modules • 1 LCC computer interface 9