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Courtesy of the Tower of David Museum (Permanent Exhibition)

FINDING THE RIGHT PATH. Shimron and Frumkin believe that a third team working on the surface pounded out acoustic signals on the bedrock to guide the underground work of the tunneling teams (see section drawing). Initially, the southern team planned to take a fairly direct route northeast from the Siloam Pool so they would intersect the northern team as quickly as possible. The northern team, however, began by excavating almost due west, a course the geologists believe was either a gross miscalculation in direction or a deliberate attempt to extend the tunnel to a well shaft in the heart of the city.

Both teams quickly realized, however, that the nearly 160 feet of bedrock and soil overburden in their respective areas made sound communication with the surface impossible, so they decided to adjust the tunnel’s course. Hezekiah’s engineers directed the tunnelers to the shallower eastern slope of the city instead (which has a more manageable overburden of between 25 and 80 feet), where the guiding signals of the surface team could be more easily heard. Partial shafts in the bedrock may have aided in the sound communication. From here the tunnelers followed the surface signals until they were finally within earshot of the other team’s voices and pick axes, as described in the Siloam Inscription. On the plan, areas in yellow have a shallow overburden and gradually progress to the deepest areas (shown in red) where it was impossible to hear the surface signals.