Recent innovations in yield-control support systems are allowing contractors to increase the rate of advance when tunnelling in difficult conditions associated with severely squeezing ground. Such systems are being implemented and proven in tunnelling projects using conventional excavation methods. The Saint Martin access tunnel along the Base tunnel of the Lyon-Turin rail line is presented as a case study to illustrate some of these developments which have been implemented successfully to deal with severely squeezing conditions encountered during excavation in a Carboniferous Formation.