Demand Response

In electricity grids, demand response (DR) refers to mechanisms to manage the demand from customers in response to supply conditions, for example, having electricity customers reduce their consumption at critical times or in response to market prices. This is different from energy efficiency, which is performing the same services but using less power. In demand response, customers, often through the use of dedicated control systems, shed loads in response to a request by a utility or market price conditions. Services (lights, machines, air conditioning) are reduced according to a preplanned load prioritization scheme during the critical timeframes. An alternative to load shedding is on-site generation of electricity to supplement the power grid. Under conditions of tight electricity supply, demand response can significantly reduce the peak price and, in general, electricity price volatility.
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Personal transit service operated on roadways to provide service on demand. Vehicles are normally dispatched and used exclusively for this service. (FTA2)

Passenger cars, vans or Class C motor buses operating in response to calls from passengers or their agents to the transit operator, who then dispatches a vehicle to pick the passengers up and transport them to their destinations. A demand response operation is characterized by the following: 1) the vehicles do not operate over a fixed route or on a fixed schedule except, perhaps, on a temporary basis to satisfy a special need; and 2) typically, the vehicle may be dispatched to pick up several passengers at different pick-up points before taking them to their respective destinations and may even be interrupted en route to these destinations to pick up other passengers. (FTA1)

Non-fixed-route service utilizing vans or buses with passengers boarding and alighting at pre-arranged times at any location within the system's service area. Also called "Dial-a-Ride." (APTA1)