metrorail speed control

What type of trip arm is used for controlling metrorail train speed?

"rail10"
What type of trip arm is used for controlling metrorail train speed?

There are no 'trip arms'. The ATP (Automatic Train Protection) part of the ATC (Automatic Train Control) system regulates train speed. Speed command ranging from 14 MPH to 79 MPH in increments of 5 MPH are transmitted from wayside train control to trains via AC track circuits on 5 frequencies ranging from 3Hz to 21.5Hz. If the train receives no speed command the train will stop. The above applies to both automatic mode (mode 1) and manual mode (mode 2).

Trains can be operated at speed not to exceed 15 MPH in manual mode (mode 2) with no speed commands with ATP only at direction of OCC (Operation Control Center).

However, here in Boston's antiquated MBTA Sytem, the speed control is dictated by Central Controls, which controls the ATO on the Oak Grove-Forest Hills Orange Line and the Alewife-Asmont/Braintree Red Line, and with the ATO Box in the cars, it displays a code, like the STOP 0 Code, 10, 25, 40, 50, 55 and even 60 codes. But in WMATA, the technology is far advanced than here in MBTA city.

However, unlike WMATA's mode 2, MBTA trains here in manual release modes can go any spped they want, up to 60 mph, and if they exceed 15 mph while on WMATA mode 2, then a penalty brake application can happen.

I will like to update on the metrorail speed control why metrorail chose automatic train protection rather than trip arms?

"rail10"
I will like to update on the metrorail speed control why metrorail chose automatic train protection rather than trip arms?

The trip arm dates to beginning of the last century. AC track circuits came shortly thereafter. The state of the art in the 1960s gave us the ability to use AC track circuits for train control and most importantly automatic speed control.

Trip arms protect against entering a block protected by red signals, AC track circuits along with the associated train board hardware also protect occupied blocks.

The AC track circuits also allow bidirectional communication. This gives the train control system the ability to automatically route trains through interlockings based on codes transmitted from train to wayside hardware and to identify the train by train number, consist, direction, location, and when the doors are open at platforms on central control displays.

I will like to thanks for answering my questions about the metrorail speed control!