The TxDOT proposed (and eventually got) 60 MPH speed limits for almost every state-controlled freeway within the city of Dallas. Dallas asked that all these roads be signed at 55 MPH. Dallas's own speed studies showed 85th percentile speeds in excess of 65 MPH on most of these roads. If proper speed zoning procedures were followed, all these roads would have been signed at 65 to 70 MPH.
(Sorry. Stupid cat barfed on this.)