E37 was the designation of one of the many pressure elevators that lead from Haven City to the Earth's surface; E37 was located in Haven's West Bank, and emerged in downtown Paris. As Paris is red-flagged by the Lower Elements Police as a high-risk area, visas are rarely approved to the general public; LEP business only.
E37 is mentioned in two of the books. In The Arctic Incident, at the beginning of the book, Holly Short - then on Traffic duty - was assigned to watch over the rarely-used chute with Chix Verbil. At that time, the whole area was deserted - the suburb had become a ghost town after the chute was closed to the public. Trolls were the only signs of life, and "When trolls began to stake out an area, you knew it was deserted." The Shuttle port was not completely empty, however - it was being used for a B'wa Kell Goblin triad smuggling operation - smuggling pencil batteries between Haven and the surface, with the use of a custom- (and badly-) built shuttle.
E37 is mentioned for a second time in Opal Deception. By that time, the goblins had been cleared out, and the shuttle port was being used by a movie company making a TV film about the B'wa Kell rebellion (exaggerating the firefight in Opal Deception with quite a large number of fake laser burns). It was the scene of what appeared to the LEP - in particular Commander Ark Sool of Internal Affairs - as Holly Short's betrayal of the LEP, and also of the death of Commander Julius Root. As the Commander pointed out to Foaly, E37 is the shute where Foaly's sensors had malfunctioned before. It is also the shute where many bad things seem to happen, often involving Opal Koboi.