Our profit recognition related to construction contracts is based on estimates of transaction price and costs to complete each project. These estimates can vary significantly in the normal course of business as projects progress, circumstances develop and evolve, and uncertainties are resolved. When we experience significant changes in our estimates, we undergo a process that includes reviewing the nature of the changes to ensure that there are no material amounts that should have been recorded in a prior period rather than as revisions in estimates for the current period. For revisions in estimates, generally we use the cumulative catch-up method for changes to the transaction price that are part of a single performance obligation. Under this method, revisions in estimates are accounted for in their entirety in the period of change. There can be no assurance that we will not experience further changes in circumstances or otherwise be required to revise our estimates in the future.

In our review of these changes for the three and six months ended June 30, 2018, we did not identify any material amounts that should have been recorded in a prior period. In our review of these changes for the three months ended June 30, 2019, we identified and corrected $4.3 million which related to prior periods. This correction resulted in a $4.3 million decrease to Transportation revenue and gross profit and a $3.2 million increase in net loss attributable to Granite Construction Incorporated during the three and six months ended June 30, 2019. We have assessed the impact of this correction to the financial statements of prior periods’ as well as to the financial statements for the three and six months ended June 30, 2019 and have concluded that the amounts were not material to those financial statements and are not expected to be material to the financial statements for the year ending December 31, 2019.

For the three and six months ended June 30, 2019, revisions in estimates, including estimated cost recovery of customer affirmative claims and back charges, that individually had an impact of $5.0 million or more on gross profit resulted in decreases to gross profit and loss before (benefit from) provision for income taxes of $161.1 million and $167.8 million, respectively, and decreases in net loss of $120.2 million and $125.4 million ($2.57 and $2.68 per share), respectively.

For the three and six months ended June 30, 2018, revisions in estimates, including estimated cost recovery of customer affirmative claims and back charges, that individually had an impact of $5.0 million or more on gross profit resulted in decreases to gross profit and loss before (benefit from) provision for income taxes of $30.2 million and $38.0 million, respectively, and decreases in net loss of $23.2 million and $29.1 million ($0.57 and $0.73 per share), respectively.

Decreases for all periods presented were in our Transportation segment. There were no increases from revisions in estimates, which individually had an impact of $5.0 million or more on gross profit, for the periods presented.

		Three Months Ended June 30,						Six Months Ended June 30,
(dollars in millions)		2019			2018			2019			2018
Number of projects with downward estimate changes			5			2			5			3
Range of reduction in gross profit from each project, net	$	7.5 - 77.3		$	14.5 - 15.7		$	8.5 - 77.3		$	5.2 - 18.3
Decrease to project profitability	$		161.1	$		30.2	$		167.8	$		38.0

The decreases during the three and six months ended June 30, 2019 were due to increased project completion costs, schedule delays, execution of a significant amount of disputed work as well as an unfavorable court ruling on a designer back charge claim partially offset by an increase in estimated recovery from customer affirmative claims. The decreases during the three and six months ended June 30, 2018 were due to higher costs than originally anticipated as well as additional weather-related costs and a decrease in estimated recovery from customer affirmative claims.