TM 5-628/AFR 91-44
(2) On curves 4 degrees and greater and on
the curved side of turnouts, the use of an additional
spike as shown in figure 6-4 is recommended.
(3) Spikes in angle bars. Spikes shall not be
installed through the slots in skirted-type, slotted
joint bars (angle bars) as shown in figure 6-5.