During construction, gas detection methods will be used for flammable gasses. The potential condition for encountering a gas or oil pocket is covered under the Tunnel Safety Orders administered by Cal/OSHA. These laws dictate the safe working environment as well as the conditions that may require removal of workers from the tunnel until they are mitigated. One of the most typical mitigations required includes increasing the amount of ventilation to the affected area. The mechanisms used for tunnel liner construction would provide a sealed work area and protect the boring machine and workers from water intrusions.