will encounter, the route to it is. There are two main methods by which open access is realised:
- The Gold route, where the publishers make a journal (or an article) open access. For commercial publishers, fees received through the proprietary model from library subscriptions must be recouped, so an APC is levied. A study of 1,370 journals published in 2010 found the range to be between US$8 and US$3,900 with an average APC of US$906 (Solomon & Bjork 2012). The Gold route need not require APCs, however. That is just one model of making it viable.
- The Green route, where the author self archives a copy of the article, either on their own site or on an institutional repository.
With Gold, the emphasis is on the journal, and with Green, on repositories. To these a third option is sometimes added, termed the ‘Platinum route’, whereby the journal does not make any APC and publishes open access, but this could be seen as a variant on the Gold route. Such journals are usually operated by societies or universities, where financial return is a lower priority than dissemination.
But there is further complexity to this picture also. With regards to the Green route, what constitutes ‘green’ can vary. Many publishers will place an embargo for a set period, meaning that an article cannot be self-archived until this has passed, which can range from six to eighteen months. In its open access mandate, the US Office of Science and Technology Policy (OSTP) allows a 12 month embargo (Holdren 2013), while Science Europe (2013) advocates only 6 months. The Gold route can be used in hybrid mode, whereby certain articles in a journal are open access, but not all of them. In this model, publishers still charge the subscription
