The "pool" is a method of distributing insurance risk in which the individual participants share overall risk with the other participants.
OTHER USES -- "The California Transit Insurance Pool (CalTIP) is a joint powers insurance authority organized under California law in 1987 in response to the lack of liability insurance coverages from the commercial insurance market. CalTIP combines the resources of public transit operators to minimize risk, increase buying power, and provide stable, affordable insurance to its members."
More Examples of Pool:
"The Oregon Medical Insurance Pool (OMIP) is the high-risk health insurance pool for the state. OMIP was established by the Oregon Legislature to cover adults and children who are unable to obtain medical insurance because of health conditions."
Further details - Pool:: Search Texas Health