What kind of radio do the modern locomotives use?

Question

Trains today can be one or two miles long with a "pusher" motor at he rear. Does constant radio communication have to be maintained for the train to operate?

How do they operate if they are in areas where radio communication is nearly impossible or not at all? Does the whole train go "dead" if you lose contact?

Answer 1

they use vhf radios to talk to bases an they have onboard intercoms

Answer 2

A mixed question.  

As far as communication goes there's nothing exotic.  Radio sets on the locomotive and the handheld sets used by ground personnel are Motorola, and the frequencies are available at radio shack along with a scanner, should anyone be interested in listening in.

Helper engine, when entrained and manned by a human, is notified via radio when the head end encounters a restrictive signal, change in speed, temporary track speed restriction, etc.  But, even when radios fail, helper engineers can do just fine by observing guages.

By way of example, if the train is stopped on ascending grade, when the helper engineer sees the brakes release on his guage, he starts pushing, whether he can move the train or not.  The release is the signal to go.  Likewise, when out and running, its a matter of "chasing the speedometer".  When the train tries to run or squat the helper will adjust his power or dynamic brake accordingly.  People seem to forget that the railroads operated for well over a century before radion communication was available.

If the helpers are unmanned, as in the case of DPUs, then the two cosists maintain constant radio contact.  These things are dangerous and nobody will ever convince me they're not.  Why?  Consider this:

When communication is interrupted, the unmanned DPUs will keep operating at the last command they received before continuity was lost.  This means, if they were in full throttle at the time, in full throttle they'll stay, for a predetermined length of time before automatically and gradually throttling off to zero.  This is a poor situation to be in as a train separation is likely and the odds of a derailment increase.

In addition, conditions can change at any time, and if the headend encounters a position where they are to reduce speed or an emergency situation develops, there is no way to shut down the things short of making an emergency application of the brakes.  At this point, the odds of a derailment skyrocket.

This is not as much of a problem where the DPUs are used in territory where the worst to be encountered is rolling hills.  But, in mountain territory, where trains are operating through canyons, tunnels, etc., continutity becomes a real problem.