underground car navigation

Hi all, I'm doing research for an application that requires accurate sub-meter localization on underground vehicles without the use of GPS. Does anybody know of a method that is capable of this? I have considered using axial measurements for absolute calculations of distance and rate, but I couldn't find any manufacturer that has a ready-made solution. Any help would be greatly appreciated.

How do you want to detect them? IE - what transponder etc if not GPS... Or rather - if vehicle position is desired, what transponders are available?

Basically, you can use dead reckoning if you know the initial position (the entrance to the underground car park) that has been obtained accurately through GPS. Axial rotations can give total distance travelled and steering angle can be used at each point to calculate the angle of travel.