I'd venture that it would depend what I was flying.. .. .In a microlight, C150, J-3, glider etc. the wingspan is significant and the landing roll short. In those cases, I think the field is almost invariably the best answer - the long flat surface of a road isn't necessary, wingtip clearance is.. .. .In something like a PA28, the landing roll is long, the wingspan relatively short and you've got a good chance of landing down the middle of a road and missing lampposts, etc. down the sides. But, it needs a lot of length to land on, and unless you get a stunning field, you're almost certain to hit something in a field landing so the motorway MIGHT be a good option.. .. .On a british motorway, I'd land with the flow of traffic. The traffic will be going rather faster than your approach speed, so will see you flying in front of them with a closure rate (them on you) of perhaps 30mph and have adequate opportunity to slow and stop. Land head-on, adding your 50-70mph approach to the traffic's 60-90, and I think the odds of avoiding a major accident are slim.. .. .Personal opinion only, all my forced landings have been succesfully in fields, in microlights.. .. .G