Time Release Studies (TRS) are a trade facilitation tool utilized by Customs to quantify the average times taken for the clearance of goods at the various entry locations in a territory (e.g. ports, airports and land borders). Their adoption dates back to the beginning of ninetiees of 20^th century, on initiative of the American and Japanese customs. At international level, their adoption is recommendend since 1994 by the World Customs Organization (WCO), that on 2002 issued also guidelines to guide their members in the correct use of such a tool.

TRS allow in particular to customs administrations to measure and break down into separate phases, time required from the arrival of goods in the importing Country to their release, in order to identify bottlenecks, delays and constraints in the customs clearance process and implement adequate corrective actions.

On 17 June 2010 the Dutch Institute for Advanced Logistics (Dinalog), network of both public and private institutions, universities and centres for research established in The Netherlands on initiative of the Ministry for Economic Affairs and the Ministry of Transport in order to conduct research activities in the sectors of logistics and supply chain management, started the single window project along with other 4 projects aimed at improving the role of The Netherlands as logistical platform in Europe.