The same photograph that you reference from the Fort Lewis collection is also printed on page 59 of RGS Vol 1. If I lay a ruler on the southern edge of Hyde St, the majority of the turntable bridge is above the ruler. Just a portion of the bridge is south of Hyde St using this method which seems to agree with the overlay. Having said that yes there does appear to be a circular pattern below Hyde St in the aerials. I also recall that someone posted a modern shot from this circular area and it was discussed a while back. I think it was Casey Akin.
Dave