Modern line signals contains one white light bulb, and, if needed, a green light bulb. The background is reflective, so that the absent of light can easily be spotted. A blue colored light are created by raising and holding a weighted lens in front of the white light bulb. A single bulb signal can show 5 aspects, while a dual bulb signal can show 8 aspects. Dual bulb signals are used before diverging lines and station. All aspects are fail-safe. Opposing signals are places 1.5-2 reungs (1.06-1.42 mi/1.71-2.28 km) apart as a protective measure against passing signals that has failed to stop aspect.
Signaling Aspect Meaning Speed limit per hour Expect No lights Stop 10 reung (7 mi/11 km) white warning 30 reung (21 mi/34 km) stop flashing white high speed warning 70 reung (50 mi/80 km) warning green restriction 25 reung (18 mi/29 km) divergence green+white restrictive warning 70 reung (50 mi/80 km) restriction green+blue restrictive clear 85 reung (60 mi/97 km) restrictive warning blue clear 115 reung (82 mi/131 km) any signal except stop flashing blue high speed clear 140 reung (99 mi/160 km) clear