"Site access/egress". At first glance I thought it was Welsh. (Most of our signs are bi-lingual.) Then I thought, 'No, wait, egress is a bird.' But that doesn't make sense.
Much pondering - by which time the traffic lights had changed and I had driven past the sign in question - led me to the conclusion that it was neither Welsh nor a bird but a real English word meaning 'the way out' (thank you Mr Chambers).
If it takes me, a reasonably articulate woman for whom the word egress does actually ring a bell, that long to decipher the sign may I suggest that it's perhaps not ideal?
On a similar note i.e. little used words, I recently spotted a van advertising 'fortnightly sales of furniture and chattels.' And I instantly had an overwhelming urge to attend a sale of chattels. 'May I interest you in this pre-loved chattel, madam?'
On a completely different note I caught a snatch of a news report yesterday about a woman who was persuaded to smuggle 20,000 euros in a condom inside her person. I cringed.
P.S. Husband pointed out that the sign should have read ingress/egress rather than access. It constantly amazes me the range of stuff Husband knows.