Complex sentence: Amusement parks began to compete to see who could have the tallest, fastest coaster, but at the same time safety was not a concern at this time, and a lap bar and strong grip were all that riding had to depend on to keep them safe.
Split into simpler sentences: Amusement parks began to compete to see who could have the tallest, fastest coaster. At the time safety was not a concern, and a lap bar and strong grip were all that riders had to depend on to keep them safe.