Hopefully most people are aware of the importance of a safecall... of having a way to get out of a situation in case it turns unpleasant...
here is some technology that uses things like GPS and check-in messages to perform a similar function

I haven't personally tested these and would say they should not stand in for:
(1) if you feel really uncomfortable / unsafe, how about not going?
(2) a friend you can trust knowing exactly where you are going and with who

but here they are and i hope that they are of some use to someone as an extra layer of security!

https://www.kitestring.io/
https://www.glympse.com/
http://getbsafe.com/
http://www.circleof6app.com/