take the route at, in weak route signaling the engineer is just informed of a diverging route. Signals in this class include Medium Clear (ARA Rule 283, see Figure), Slow Clear (Rule 287), Limited Clear and Diverging Clear. Diverge to Stop - Same as above only the train can expect to stop at the signal after the interlocking. These signals include Medium Approach (ARA Rule 286, see Figure), Slow Approach (Rule 288) and Diverging Approach. Combination Signals - These combine functions of a "Diverge to" signal with an "Approach Speed" signal and occur in areas of complex trackwork where there are no intermediate signals between one interlocking and the next. In the United States only a few combination signals like Medium Approach Medium, Medium Approach Slow and Diverging Approach Medium/Slow are ever found in rulebooks and not frequently used in practice. The Canadian standard rulebook contains signal rules and aspects for every possible combination. Restricted Speed Signal - This class of signals is displayed for trains moving into a block where a track circuit has been de-energized or does not exist. A "shunted" track circuit indicates either the block is occupied by another train or railcar, or there is a problem such as a broken rail or flooded track. Where a track is not protected by track circuits that track must be presumed to be occupied. As the name implies this signal requires trains to move at Restricted speed, specifically with the ability to stop short of an obstruction. Restricted speed signals take many forms including Restricted and Restricted Proceed (ARA Rule 290, see Figure) where trains must simply pass the signal at restricted speed and also Stop and Proceed (Rule 291), where a train must come to a complete stop before proceeding at restricted speed. Stop and Proceed has fallen out of favor with most freight railroads due to the fuel and time savings of allowing the trains to not come to a complete stop. This aspect class can be displayed on almost all railroads in North America. Stop Signal - Stop signals are displayed on Absolute signals, in fact the ability to display an absolute Stop is part of that signal type's definition. Stop is the most important signal as passing a signal at Stop presents a serious risk of accident. Engineers committing a Stop signal violation automatically have their Federal certification suspended and are frequently fired. Stop