Picture: http://imgur.com/a/WDxQs.
Welcome to the world of software development :p
Anyway, we'll need a saved game where it can be reproduced.
Give me your email address so I can email it to you. :)
I don't work on the code myself, right now only James does. Also, just in case someone else wants to help, I'd suggest you upload it to Dropbox or Google Drive for example so everyone can have a look at it.
By the way, out of bounds errors are the most common type of crash-causing bugs and are rather easy to fix when you have a game where they can be reliably reproduced, so sending the saved game with the report should be standard procedure for them ;)
The link to the .sve: https://drive.google.com/open?id=0Bzy63vjRdV2_RWU4X01Rc0h2ZTA. Go to Applingcaster North Junction and delete the whole up junction in the southbound direction and you'll get your crash.
Splendid - a saved game and a description of how to reproduce the crash: that is just what is needed in a bug report. Because of that information, I have been able to reproduce and fix the problem. Sorry that you have had trouble.
It has not been uploaded to the devel new builds yet.