then you need a loco that is able to contact the dispatcher! At the entrance of Rylestone Quarry is a stop sign: This has the same effect as a red signal, even if you have a route defined over it. You have to contact the dispatcher and wait until you get the message to proceed at reduced speed. If you used a loco that has no phone, change that prior to this sign into a Class 09 Green and use the walkie talkie.
You don't have spawn another locomotive, with steam you press the Tab button and call a dispatcher. Isn't this possible with Xbox/Pc?