In this paper, we investigate the bit error rate (BER) performance of the max-dmin MIMO precoder in presence of impulsive noise in a railway tunnel. Measurements showed that the received signal at the antenna on the moving train roof near the catenary suffers from electromagnetic noise interference (EMI). This implies that the traditional Gaussian noise model is no longer valid and an impulsive noise model should be considered. Based on this observation, we analyze the performance of the max-dmin MIMO precoding technique, based on the minimum distance criterion, with impulsive noise modeled as an alpha-stable distribution. We present two points of interest: i) an approximation of the error probability of the max-dmin precoder, applied to the MIMO context in tunnel, in the presence of heavy tailed alpha-stable impulsive noise, and ii) the performance evaluation, in terms of bit error rate, of a complete communication system, considering a MIMO channel model in tunnel and impulsive noise, both obtained by measurements. Two soft detection techniques, providing the soft decisions to the channel decoder, are proposed, based on the approximation of the impulsive noise by either a Gaussian or a Cauchy law.