A lighting system for use along a length of an underground passageway, the system including: a base station located at or near an end of the length of the passageway, said base station including at least one power source; a plurality of light modules extending from the base station in a serial arrangement and spaced at least partially along the length, each light module including at least one visual signalling device capable of emitting light for ordinary operations within the passageway and at least one visual signal; at least one cable extending from the base station and interconnecting the light modules with the base station and the power source; and a controller operatively associated with the base station, said controller being in communication with at least one sensor configured to sense an environmental condition, wherein the light emitted for ordinary operations is white light and the at least one visual signal is a flashing red light, wherein said controller is configured to continuously monitor said sensor and selectively activate the at least one visual signal of any one of the light modules when an abnormal or emergency said environmental condition is detected or upon receiving a manual command, and each said light module includes a dedicated microprocessor operatively associated with the at least one visual signalling device for controlling operation of the at least one visual signalling device in response to receiving instructions from the controller, a redundant wireless communications module for providing a redundant wireless communications path should the at least one cable connecting light modules to the base station be damaged, and a redundant power source for powering the at least one visual signalling device and other electrical components of the light module should the at least one cable connecting light modules to the base station be damaged, and wherein, when an abnormal or emergency said environmental condition is detected near or within the underground passageway and the passageway is deemed unsafe, the light modules are configured to flash the at least one visual signal relative to one another in a sequential and coordinated pattern to direct a person towards a safe zone or away from the abnormal or emergency said environmental condition detected. a base station located at or near an end of the length of the passageway, said base station including at least one power source; a plurality of light modules extending from the base station in a serial arrangement and spaced at least partially along the length, each light module including at least one visual signalling device capable of emitting light for ordinary operations within the passageway and at least one visual signal; at least one cable extending from the base station and interconnecting the light modules with the base station and the power source; and a controller operatively associated with the base station, said controller being in communication with at least one sensor configured to sense an environmental condition, wherein the light emitted for ordinary operations is white light and the at least one visual signal is a flashing red light, wherein said controller is configured to continuously monitor said sensor and selectively activate the at least one visual signal of any one of the light modules when an abnormal or emergency said environmental condition is detected or upon receiving a manual command, and each said light module includes a dedicated microprocessor operatively associated with the at least one visual signalling device for controlling operation of the at least one visual signalling device in response to receiving instructions from the controller, a redundant wireless communications module for providing a redundant wireless communications path should the at least one cable connecting light modules to the base station be damaged, and a redundant power source for powering the at least one visual signalling device and other electrical components of the light module should the at least one cable connecting light modules to the base station be damaged, and wherein, when an abnormal or emergency said environmental condition is detected near or within the underground passageway and the passageway is deemed unsafe, the light modules are configured to flash the at least one visual signal relative to one another in a sequential and coordinated pattern to direct a person towards a safe zone or away from the abnormal or emergency said environmental condition detected.