A source where we can only read the abstract. Not much different from Wikipedia which sites several sources:
"In Roman-style crucifixion, the condemned could take up to a few days to die, but death was sometimes hastened by human action. "The attending Roman guards could leave the site only after the victim had died, and were known to precipitate death by means of deliberate fracturing of the tibia and/or fibula, spear stab wounds into the heart, sharp blows to the front of the chest, or a smoking fire built at the foot of the cross to asphyxiate the victim."
[57] The Romans sometimes broke the prisoner's legs to hasten death and usually forbade burial.
[92] On the other hand, the person was often deliberately kept alive as long as possible to prolong their suffering and humiliation, so as to provide the maximum deterrent effect.
[89] Corpses of the crucified were typically left on the crosses to decompose and be eaten by animals.
[89][106]"
Crucifixion - Wikipedia
Here is another source that supports the non-burial of crucifixion victims:
Crucifixion - New World Encyclopedia
"The goal of Roman crucifixion was not just to kill the criminal, but also to mutilate and dishonor the body of the condemned. In ancient tradition, an honorable death required burial; leaving a body on the cross, so as to mutilate it and prevent its burial, was a grave dishonor."
And another:
"It was usual to leave the body on the cross after death."
Roman Crucifixion
And one more:
"And the proof did not end with your last breath. Romans left bodies on the cross for clear and distinct reasons.
Everyone wanted a decent burial in the ancient world. It was far more important to people then than it is to people today. A decent burial, for many, was required for a decent afterlife. It honored the body of the one departed. Not to receive a decent burial was disgusting, scandalous, gut-wrenching, debasing, humiliating. And so Romans did not allow crucified victims – especially enemies of the state – to be buried. They left them on the crosses as their bodies rot and the scavengers went on the attack. To allow a decent burial was to cave into the desires precisely of the people who were being mocked and taught a lesson. No decency allowed. The body has to rot, and then we’ll toss it into a grave.
And the proof did not end with your last breath. Romans left bodies on the cross for clear and distinct reasons."
Why Romans Crucified People