some of the decisions of the highways authority are puzzling. the first section of the M1 to be fully lit was between J16 and J18; this was done in 1973-ish after a series of bad accidents over the previous winter, that particular stretch (past watford gap services) was particularly prone to fog, etc. as part of the works to convert the M1 into 4 lanes (without shoulder), all the carriageway lighting has been removed, presumably for energy cost reasons. there have been no accidents since that was done, but that could well be because of the 50mph speed limit which, with the average speed cameras, is 89% observed by traffic.
we shall see, but it does rather suggest that safety is trumped by money every time.