The crew drives one or two miles ahead and waits for the runner to approach. They will then run across the street to meet the runner and supply whatever is needed, which is usually a new water bottle with ice, a new ice bandana, and a spray down with ice water from the fertilizer pump, and maybe some calories. All the runner's ice, in any form, will melt and completely evaporate by the next mile. This is done over & over & over again for 135 miles! This picture of my crew - minus Bonnie who took the picture - is very early in the race, "pre-entropic".
(Oh, Bless my dear Larry, for he knows not what he has gotten himself into!)