Food for thought, but I'm curious what effect all of these tightly grouped buildings with large concrete (non conducting) mates and or tub foundations are having on the bulk internal and surface impedance (Z) of the ground and what if any RC (resistor*capacitor) time constant (tc) is being produced from all the densely placed structures.
I ask, having already noticed two rather interesting RC tc effects during a direct lighting strike of the Sears Tower and the Wheelock building in Shanghai.
i) lighting struck the upper most portion of the west, Sears Tower antenna mast, then approximately 0.5-1 second post the lighting strike, a second discharge event was observed spanning the upper portion of the two mast, similar in appearance to a discharging though position stationary, Jacobs Ladder. The event lasting about 0.5 second to complete and in that time, implied a voltage potential on the order of many millions of volts existed between the building itself and true, not relative, ground potential. It not being uncommon to see normal, relative ground potential on a building increase with height and routinely monitored by some hospitals.
ii) While standing outside in the rain and across the street from the nearly completed skeletal phase of the Wheelock building in Shanghai, observed the building tower crane get struck by lightning, the stored electric charge in the compartmentalized, steel structure taking about 1 second to discharge post the lightning strike. The tall, nearly topped out structure producing a loud sizzling noise while dissipating the electric charge and tc function relative to ground impedance (Z).
Thus, I am curious if and how much the surface impedance (Z) has changed in Chicago’s central loop and if there has been any effect on electrical discharge paths along with discharge time (RC tc) for much of the central loop is bulk concrete that is enclosed on three sides (N, E, W) with fresh water, the south direction being the only non restricted path.
Also, will buildings of the future, as urban areas become more dense, the large buildings produced with more non conducting (capacitating) materials, need for general safety, complex building grounding arrays though perhaps not as long as that configured about the former US Coast Guard, Loran-C transmitter building located in Haiku Valley, Oahu?
The large transmitter building being attached to many thick copper foil (~3.5" x 0.25") conductors that extended in multiple directions for ~1/5 mile. The building transmitting so much LW RF power that when standing next to the transmitter coils in the transmitter room, could easily hear without the aid of a radio receiver (naked ear) the Loran-C RF transmission and to which I still found to be pretty intense, I coming from high power weapons fire control radar background. One could hold the end of a long ceiling style florescent light bulb tube outside and it would glow on its own.
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