What is the ruling on work that led to the death of a worker, given that safety conditions were not met due to the engineer's refusal and reliance on available labor, which resulted in my being accused of causing accidental death?

The engineer in charge was negligent in ordering you to work without providing safety specialists, and the guardian (wali al-amr) has the right to punish him. Your agreement to start work without refusal is also an act of negligence that warrants punishment. There is no blood money (diyah) or expiation (kaffarah) upon you if the deceased worker was an adult of sound mind, because he could have refused. So, if someone orders a competent person and he acts upon it and perishes, the one who gave the order is not liable.

As for the driver, if the accident occurred without negligence on his part, there is no liability or expiation upon him. However, if he could have avoided the accident and did not, this is involuntary manslaughter (qatl khata'), which obligates him to pay expiation (freeing a believing slave or fasting for two consecutive months) and blood money (diyah) (paid to the heirs of the deceased and borne by the 'aqilah - the male relatives on the paternal side). It is necessary to refer to the competent authorities and the Sharia judge to determine the extent of the driver's negligence.