Ride Share as Shuttle for Multiple People at Multiple Times

I have not heard of ride share apps being used for this application, but it would really be helpful.

Here is the situation:

I am hosting a conference. Some people attending the conference will need a ride to the conference site from their hotel. I would like to provide them this service. However, renting a shuttle for the full day is really expensive. I would prefer to set up a ride share account for the conference and allow riders to call for their ride on that account. They can come and go as they please and no driver has to sit around for hours waiting for someone who needs a ride. 

Is this possible?