If a street typically had 600,000 people travelling on that every day and then for a time period that number dropped, how long would it take for that to make the street no longer a Reshus Harabbim?
For example (this is purely hypothetical. I haven't actually looked into the statistics at all), if Ocean Parkway was a Reshus Harabbim by virtue of having 600,000 people travelling on it every day, and then due to orders to suspend non-essential travel and work because of COVID-19 that number temporarily dropped to 300,000, would it become a Carmelis, which would mean that the Eruv could become valid? How many weeks in a row would it need to have less than 600,000 people travelling on it to go down a level?
I'm assuming that if there was construction and for one week there were less than 600,000 people travelling on it that wouldn't be enough to make it lose it's status of a Reshus Harabbim, but I don't even know if that's true.
Any sources would be appreciated. Thanks.