  The Milky Way spiral arm dynamics is studied using the birth place of open
clusters. We separately study the nearby spiral arms, and find evidence for
multiple spiral sets. In particular, the Sagittarius-Carina arm appears to be a
superposition of two sets. The first has a pattern speed of
Omega_P,Carina,1=16.5^{+1.2}_{-1.4sys}+/-1.1_{stat} (km/s)/kpc, while the
second has Omega_P,Carina,2=29.8^{+0.6}_{-1.3sys}+/-1.3_{stat} (km/s)/kpc. The
Perseus arm located at larger galactic radii exhibits only one clear set with
Omega_P,Perseus=20.0^{+1.7}_{-1.2sys}+/-1.6_{stat} (km/s)/kpc. The Perseus and
"slower" Carina arms are most probably part of an m=4 set. The Orion "armlet"
appears to have a pattern speed of Omega_P,Orion=28.9
^{+1.3}_{-1.2sys}+/-0.8_{stat} (km/s)/kpc. In other words, both the "faster"
Carina arm and the Orion arm are nearly corotating with the solar system.
