Status Updates From A Transatlantic Tunnel, Hur...

later on it really starts leaning hard on the corporate espionage thriller angle as assassination attempts at the protagonist (one of the main designers of the transatlantic tunnel) and sabotage against various vehicles he uses (including a "helithopter") become more common and he teams up with a private detective to solve them - full of scenic globetrotting locations and fistfights in dark alleys

Many interesting things that Harrison does with the Jules Verne pastiche premise. E. g. instead of setting it in the late 19th century he sets it in an alternate 1970's where the American Revolution failed, resulting in America still being a British colony; likewise much of the plot revolves around the conflicts between different private companies and government agencies involved in building the transatlantic tunnel.