I was intrigued by the work of Scott Conarroe, in particular his By Rail series which is quite beautiful. What intrigued me more however was the explanation of his technique and his thoughts on the process;
I use long exposures for a number of reasons. The pragmatic explanation is that they are necessary in the subdued light and deep depth of field I like to work with. Conceptually, I like that scenes change continuously while I photograph them, that they look different at the beginning of an exposure than at the end. Long exposures increase a photograph’s autonomy because the truthfulness of its negative doesn’t portray a specific instant that appeared a certain way, it portrays a compilation of moments blended together; they underscore the camera’s roles of abstractor and editor as well as recorder. And long exposures introduce an element of chance into the precision that view cameras are capable of.
I try to complement twilight with streetlamps and other electric highlights when I’m able; I like projecting tension between the vast shifting romance of a sunset and the arbitrary on/off nature of light bulbs. And, yes, I’ve probably invested in these rhetorical positions because I like how dawn and dusk look in photographs. The painterly effect you describe has to do with latitudes of light. I generally work with sky that’s about as close to dark as it is to bright; when the tonal transition from sky to landscape is less abrupt than we are accustomed to seeing in photos the sense of visual unity is greater. I suppose it is slowness and deliberateness in the process that comes across as painterly.
The shortest exposures in By Rail are Streetcar Stop, New Orleans LA (It was maybe 15 seconds, the length of time the streetcar stops when only a person or two get on early in the morning) and Boaters, Kalamalka Lake BC (probably a second or two). The longest exposures are fifteen or twenty minutes: Canal, Cleveland OH and Cul De Sac, Hawthorne CA are among them.