Eight-lamp CPLs are often found near rail yards because they have the upper-left
and lower-right lights necessary to display a "Restricting" aspect. A Restricting
aspect advises the train's operator to proceed without stopping, but do so at a
speed slow enough to stop before any track obstruction he may observe on
When lit, the Restricting speed indicators are a slightly blue-tinted white color
like that of the Moon, hence they are sometimes called a "lunar" aspect. The
example photo at right comes courtesy David Malohn. The lunar aspect
is also used to alert the operator that he is entering unsignalled territory and
thus must proceed cautiously and employ his own judgment.
Few 8-lamp CPLs are to be found within the area covered by these tour pages.
Other known locations are on the Capital Sub (Washington Branch) near
Jessup and Savage stations. If you've found others, please let me know their