(from ttt in db.SheduleDetails
 where (from x in db.SheduleDetails where x.StationId == 1 select x.StationId) ==
 (from c in db.SheduleDetails where c.StationId == 6 select c.StationId)
 select ttt).ToList();

var res = (from d in db.RouteDetail
                       from m in db.RouteDetail

                       join o in db.SheduleDetails
                       on d.StationId equals o.StationId

                       join z in db.SheduleDetails
                       on m.StationId equals z.StationId

                       where (d.Station == "Гродно" 
                       &&
                       m.Station == "Лида")
                       && d.Route.RouteId == m.Route.RouteId
                      
                       select new SheduleSearchResult()
                       {
                           StationId = d.StationId,
                           StationName = d.Station,
                           RouteId = d.Route.RouteId,
                           TimeArrival = o.TimeArrive,
                           TimeDeparture = z.TimeDeparture,
                       }).ToList();