WASHINGTON — The engineer on Amtrak Train 188 remembers speeding up, he remembers a curve in Philadelphia that can “sneak up,” and he remembers his body lurching as the locomotive entered the bend much too fast just before it derailed last May, killing eight people and injuring more than 200.

But the engineer, Brandon Bostian, told investigators that he remembered little about the exact moment the train hurtled off the rails. And he did not explain why it sped to 106 mph as it approached a 50-mph curve, according to transcripts of two interviews released by the National Transportation Safety Board on Monday.

When Bostian came to, emergency crews already were pouring into the scene of one of the most devastating rail accidents in recent memory.

Bostian’s statements were part of more than 2,000 pages of documents the safety board released as it completed the fact-finding phase of its investigation and turned to its analysis of what went wrong.

Included are harrowing accounts of crew members thrown through the train; police calling for more tourniquets; and one conductor groping for his hat amid the wreckage, “so that people would be able to see someone in charge of the situation.”

Investigators’ summaries also detail the trip’s final moments as the train traveled north. Bostian had pushed it to full throttle as it approached the Frankford Junction curve, hitting the emergency brake just three seconds before the train derailed.

The documents confirm much of what the NTSB has already said. There were no mechanical, track or signal problems. There was no “smoking gun,” an NTSB official told reporters.

Bostian, 32, was not under the influence of alcohol or drugs, and was not using his Samsung Galaxy cell phone for calls, texts or data. He told investigators he was in fine health.

NTSB investigators will use the documents as they try to determine a probable cause for the crash and make recommendations to improve rail safety. Those steps are expected in the spring.

But with so many factors ruled out, much attention has focused on human error and why Bostian sped up as he approached the curve.

Some engineers and members of Congress have speculated that he simply lost awareness of where he was on the trip from Washington to New York. Along that route, on some stretches, the speed limit increases to 110 mph.

A few weeks after the crash, Bostian’s train engineer’s certificate was suspended, the NTSB documents show.