So as far as speed goes, you're really not losing much by having a Slow Approach instead of a Medium Approach. The train is still going to have to approach the next signal prepared to stop.
You are losing time. The train had already approached the Stop-and-Proceed preparing to maybe stop, then proceed at restricted speed (< 15 m.p.h.) throughout the entire length of the block. Had the Stop-and-Proceed clear off to Approach, the train could have proceeded at medium speed (not exceeding 30 m.p.h.) instead of the slow speed (not exceeding 15 m.p.h.) that it received with the Slow Approach.
In either case (Slow Approach or Approach), only one block ahead was clear.
Once again, as I said, Slow Approach does not mean the train needs to stay at Slow Speed. As NORAC Rule 288 (Slow Approach) states: Proceed prepared to stop at the next signal. Slow speed applies UNTIL entire train clears all interlocking or spring switches, then Medium Speed applies. It was my understanding that the signal upgraded itself just before the train in question passed it, but I could have misunderstood Lackawanna565. If he meant that the train stopped then proceeded and eventually cleared the following block allowing the signal to upgrade to a Slow approach, then I misunderstood. I was simply stating that if the train was already approaching or stopped at the signal and it upgraded to a slow approach before passing it, that the time loss would be negligible compared to if it had upgraded to a Medium Approach. Regardless of whether it was this train receiving the Slow Approach indication or the next train, I stand by my point. If he received the Stop and Proceed indication, and then proceeded at restricted speed, then sure; they lost lots of time haha. But seeing as it was a test train and not a revenue run, it didn't really matter anyways. I was merrily referring to whatever train is going to approach this signal in question and pass it as a Slow Approach. I've got to know at least a little something about this seeing as I used to work with the stuff everyday out in the field before I switched from Signals to the CETC side of things .
Sorry for any misunderstanding on my part.