Complex sentence: America's National Forests are currently covered with 386,000 miles of roads--enough to encircle the earth 15 times--and a $4.5 billion maintenance backlog exists on National Forest roads according to the agency's own estimates.
Split into simpler sentences: America's National Forests are currently covered with 386,000 miles of roads, enough to encircle the earth 15 times. A $4.5-billion maintenance backlog exists on National Forest roads, according to the agency's own estimates.