The NSW Resources Regulator has finalised its causal investigation into the heavy vehicle collision on May 27.

The investigation was undertaken in conjunction with mine operators, equipment manufacturers and worker representatives and identified several safety improvements.

Resources Regulator chief inspector of mines Garvin Burns said the collision shunted the excavator leaving the driver trapped. The excavator driver was rescued and was not injured.

"The incident was of particular interest as the trialling and use of autonomous and remote-controlled equipment is increasing in mines throughout NSW," he said.

"As a result, an investigation into the cause was immediately launched to provide a better understanding of the contributing factors and to allow us to quickly pass on lessons learned to industry.

"The investigation identified a number of contributing factors to the incident including poor sight lines and a breakdown in communications."

The investigation and subsequent actions by the operator identified a number of key engineering and technology measures that have since been implemented to prevent reoccurrence, according to Burns.

"These include the installation of a proximity awareness and autonomous stop system on all machinery and portable units for staff working in the area, installation of an aerial camera and increased separation between machinery," he said.

"Any mine operator using or considering the use of autonomous machinery should review the full investigation report to see if any of the lessons can be applied to their operations."

A Peabody spokeswoman said the safety of employees is Wilpinjong's number one priority and immediately following the incident Peabody began a thorough internal investigation into its causes.

"The company has also fully cooperated with the NSW Resources Regulator's review," she said.

"Peabody's internal investigation identified a number of key engineering and technology improvements regarding the use of SATS dozers at Wilpinjong.

 "These measures have been fully incorporated into SATS operating procedures at the mine prior to the release of the Regulators report."

These measures include fitting two-stage proximity awareness systems to excavators - prompting an alarm to sound when a dozer is in close proximity to an excavator, and then automatically stopping the dozer if it continues and breaches a second barrier;  fitting autonomous stop systems to manned excavators - allowing the operator to remotely stop all SATS dozers from the cabin; and the requirement that all employees entering a SATS operating area on foot carry an automatic stop device.

The mine has also created guidelines for all employees working in a SATS operation area; defined minimum separation distances between manned equipment between manned equipment and SATS dozers; and created a process for the testing and allocation of automatic stop devices.

"We will continue to carefully monitor the effectiveness of these new procedures to ensure we offer the highest possible protection to the Wilpinjong team," the spokeswoman said.