Sunday to Thursday are counted as full working days, and Friday as half a working day, based on numbers of truckloads and workers passing through checkpoints. This ceased on September 5, then recommenced on September 7, with about 7,800 workers permitted into settlements in the West Bank, and about 3,000 permitted into Erez Industrial Zone and settlements in Gaza. Internal closure was lifted on 15 September and the lifting of the comprehensive closure began in stages on 17 September. It is difficult to estimate with certainty the costs of closure, as many effects are indirect and lagged. Economic costs also vary with the duration and intensity of the closure, and are subject to seasonality.
Internal closures increase significantly the overall cost of closure.
The direct loss each working day can be estimated as the number of persons employed prior to closure, multiplied by the average wage. Internal closure caused additional amounts of unemployment. A small proportion of workers previously employed in Israel and disemployed by the closure find alternative employment in the WBG, mainly in agriculture. Direct losses are also accrued through losses of trade income. The IMF has projected that total exports for 1997 would be USD 366 million which, when divided by the 277 potential workdays in the year, yields average 1997 daily WBG export revenue of USD 1.3 million.