The Competition Council (CC) urges the authorities to avoid the closing of addenda to contracts awarded through public tender, because these can increase by up to 50% the initial value of the work. Following an investigation performed on the roads and highways construction market, the CC found that "there are situations in which, by signing addendums, the winner of the tender (the operator that offers the lowest price) negotiates directly with the contracting authority a new value of the work. This value can become larger than the original submissions made by its competitors." After the cross-examination there were initiated four possible investigations of illegal agreements of cartel type, aimed at the extraction/processing and marketing of mineral aggregate quarry, the participation with rigged bids in auctions organized by DRDP Craiova and the market sharing between several companies active in the road construction works under the administration of DRDP Brasov and DRDP Timişoara. The investigations are currently in progress and, thus, additional information is not yet available. According to the data included in the quoted report, during the period June 2010 - June 2011, for 96 contracts aimed at the execution of construction works and service for roads, there were closed 203 supplementary amendments. No more than 23 of these amendments included significant changes of the initial value, between 10 % and 50%, whilst for two documents the baseline increased even more than 50%. This is not characteristic solely for the Romanian market. According to a report released by the European Court of Auditors regarding the infrastructure works undertaken through EU funds in Germany, Greece, Poland and Spain, the costs of up to 46 % of the audited projects rose by more than 20% during the execution stage in the period 2000-2013. On the local road construction market are active approximately 640 companies. The associations between companies in order to participate at auctions, as well as the presence of a company in two or more associations for participating at tenders taking place at the same time are common and represent the characteristics of this market.