An article in the Wall Street Journal (Jan 30, 2012) describes the impact of customer delays on the US economy as $ 100 billion, 0r $ 750 per commuter.  But adding taxis is estimated to increase congestion – the equivalent of adding 40 private cars, as does expanding roads.  One alternative described is congestion pricing – which would incent deliveries to grocers, department stores etc to occur in cheaper off peak hours.  But will congestion pricing have to be preceded by investments in mass transit to convince commuters to switch ? Will the need to deliver at nonstandard hours increase costs for retailers even as it decreases congestion costs ? How should consumers be made to absorb the pollution externality associated with their driving decisions ?  Will changes in the pricing of road access cause higher finished goods inventory, thus driving up working capital requirements ?