Knowledge Problem: Road Congestion Pricing in Stockholm Stockholm is also using this experiment as an experiment in democracy: they are putting the congestion pricing to referendum. The six-month trial period has ended, and residents will soon vote in a referendum on whether or not to keep the system. Officials say that if a majority votes against the system they will dismantle all of the equipment in which they have invested, which was extremely expensive. in collected.writingswith congestion.pricingpoststockholmtransportation