Efforts to increase speed limits on Iowa freeways and rural roads failed in the Legislature this year amid safety concerns. But officials acknowledged such moves are popular with drivers and likely will come before lawmakers again. One measure would have allowed speed limits of 75 miles per hour on some stretches of interstate freeways, up from the current 70. Two other bills aimed to raise speed limits on some rural, two-lane roads from the current 55 mile per hour limit.