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Cab Signal System
All of SEPTA's Regional Rail system operates on tracks that support in-cab signalling, except for:
- R2 between Warminster and Glenside
- R5 between Doylestown, Lansdale, and Glenside (Lansdale-Glenside to be upgraded with cab signals)
- R5 between Overbrook and Valley interlocking
- R6 between Cynwyd and Valley interlocking
- R6 between Norristown (Elm St.) and 16th Street Junction
The Silverliner V spec has the following information: The cab signal system uses two signal carriers at 100 Hz and 250 Hz. The "code rate" is the number of times that the carrier signal is interrupted per minute.
100 Hertz
Code Rate |
250 Hertz
Code Rate |
Cab Signal
Mode |
Non-Cab Signal
Territory |
Speed Limit |
| 420 |
N/A |
Enter Non-Cab Mode |
No Aspect Displayed |
79 MPH |
| 270 |
270 |
Clear |
Enter Cab Signal Mode |
100 MPH |
| 270 |
N/A (except for 270) |
Flashing Clear |
Enter Cab Signal Mode |
60 MPH |
| 225 |
N/A |
Restricted |
Enter Cab Signal Mode |
20 MPH |
| 180 |
180 or No Code |
Clear |
Enter Cab Signal Mode |
100 MPH |
| 120 |
120 |
Flashing Clear |
Enter Cab Signal Mode |
80 MPH |
| 120 |
N/A (except for 120) |
Approach Medium |
Enter Cab Signal Mode |
45 MPH |
| 75 |
75 or No Code |
Approach |
Enter Cab Signal Mode |
30 MPH |
| 50 |
N/A |
Restricted |
Enter Cab Signal Mode |
20 MPH |
| No Code |
N/A |
Restricted |
No Aspect Displayed |
20 MPH-Cab Signal
79 MPH - Non-Cab |
N/A - Equipment shall ignore all code rates and frequencies except those combinations which
are listed.
No Code - The carrier frequency may or may not be present. If the carrier is present, it is in a
steady state.
Enter Non-Cab Mode - The Aspect Display Unit shall display a Restricted Aspect with code
present.
Source: SEPTA Silverliner V Technical Specification. August 2005.
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