  We study the quantum critical behavior of the plateau-insulator (PI)
transition in a low mobility InGaAs/InP heterostructure. By reversing the
direction of the magnetic field (B) we find an averaged Hall resistance \rho_xy
which remains quantized at the plateau value h/e^2 throughout the PI
transition. We extract a critical exponent \kappa'= 0.57 +/- 0.02 for the PI
transition which is slightly different from (and possibly more accurate than)
the established value 0.42 +/- 0.04 as previously obtained from the
plateau-plateau (PP) transitions.
