Estimation Cost Method Using Cost Significant Model On Channel Work in The Public Work In Sidoarjo W Oetomo 1 , J Rochyantine 2 , K Koespiadi 3 , H T Tjendani 4 {abarokaboel@yahoo.com 1 } 1,2,3,4 Universitas 17 Agustus 1945 Surabaya, Indonesia Abstract. The calculation of cost estimation that has been done so far in the Office of Public Works and Spatial Planning of Sidoarjo Regency was made based on experience in similar projects in previous years without any specific method, so that can not be identified any work that significantly affects the total cost the project. So that required an estimation method that is considered quite accurate and significantly affect the cost of the project, namely Cost Significant Model. This study aims to determine the components of work that significantly influence the total cost of channel development in Sidoarjo and calculate the estimated cost model of channel development with the method of "Cost Significant Model". The result of data analysis is known that cost significant item is the sum of percentage of work cost ≥ 80% of total cost of work that is stone masonry work, concrete, reinforcement, pile, and stone pitching. The most influential/significant work to the planning of development project per m channel work is stone masonry work, then sequentially are pile work, reinforcement work, and concrete work. The estimated model produced is Y = 71.864,499 + 1,257X1 + 1,235X3 + 0,990X4 + 1,605X5, where X1 is stone masonry work, X3 is concrete work, X4 is reinforcement work, and X5is pile work. With the accuracy of cost estimation of the significant cost of the model between -18,7.0% up to + 10.5%, with an average accuracy of 0.2% and the value of Cost Model Factor (CMF) of 1.0000 then the estimated model obtained very well. Keywords: channel, cost significant model, cost 1. Introduction Protection of river restoration sections through structuring riverbed, river border arrangement, and river channel rehabilitation. Protection of river borders, in this case, is also very influential in the interests of flood control. River development is realized in the form of river utilization, in Indonesia, in general, it is used for agriculture, environmental sanitation, industry, tourism, sports, defense, fisheries, power generation, and transportation. Control of the destructive power of river water is carried out through flood risk management, which is intended to reduce the risk of magnitude and vulnerability of flooding. One effort can ACHITS 2019, July 30-31, Surabaya, Indonesia Copyright © 2019 EAI DOI 10.4108/eai.30-7-2019.2287740