Beginning in January 2018, an Opal Park & Ride trial scheme was introduced at selected commuter car parks. Passengers are able to park their cars for free for up to 18 hours if they take public transport and use the carpark using the same Opal card. The scheme is intended to reduce the number of spaces used by those who aren't catching public transport. Transport for NSW also sells a number of mobile phone case accessories that incorporate a pocket for the Opal card. First introduced in December 2017, OpalPay is a facility allowing Opal cards to be used to pay fares on a number of privately owned services that operate independently from Transport for NSW's contracted services, and on on-demand minibus services. Fares on these services are set by the owner of the service and Opal's regular discounts do not apply. Concession fares are accepted on some services. OpalPay can be accepted on some private ferry services and On Demand bus services. By June 2016, 7.7 million cards had been issued. The most widely used card types (in descending order) were Adult, Senior/Pensioner, Child/Youth and Concession. Two billion trips had been taken on the Opal network by May 2018. An average of 13 million trips were taken each week and there were more than 3.7 million Opal cards in active use. Transport for NSW has stated that customers forget to tap off after about 3% of journeys, so they are charged the default fare. The Opal electronic ticketing system has won a range of awards reflecting excellence in design for its unique card reader poles used at ungated ferry wharves, light rail stops and railway stations. In addition, the project and its implementation were recognised for excellence by Infrastructure Partnerships Australia. On 12 March 2014, Opal was awarded Australia's 2014 Smart Infrastructure Project of the Year. The introduction of Opal caused debate over the different fare structures of Opal and the former MyZone paper tickets. Despite being cheaper than single cash fares, Opal single fares were more expensive than the bus and ferry TravelTens, and Opal provides no equivalent to the all-you-can-use MyTrain or MyMulti periodical tickets. An unofficial fare comparison site called "Opal or Not" claimed that more than half of all the public transport trips it compared were more expensive using Opal than with paper tickets. Transport for NSW disputes the site's findings, calling it "riddled with errors" and stating that only 7% would "potentially" pay more, but refused to release the analysis behind that figure.