Based off:
https://www.nj.gov/transportation/refdata/traffic_orders/speed/rt46.shtm

Section a.1.i.1.A (It's the first entry)
Zone 1: 45 MPH between Route I-80, Route US 46 and Route NJ 94 Interchange and 1,900 feet east of Walnut Road (approximate mileposts 0.0 to 1.39); thence

Which is consistent with the speed limit signs before it.