Right now there’s a lot of construction taking place in the park as old electrical and plumbing systems are being upgraded. To help protect the visitors, wildlife and the crews, the National Park Service is making sure you’re following all driving regulations and maintaining a safe speed while in the park.
In all construction zones the speed limit is 25 or as posted. On normal park roads the speed limit is 35 unless otherwise posted.
I can honestly say, nothing spoils your trip like getting a speeding ticket *cough*. Slow down and play it safe.