Driving from Sukhumvit to Suvarnabhumi

[Samh]

I usually stay on Sukhumvit and if driving to the airport or Pattaya I go up Asoke and right onto Phetchburi Road then left onto Thanon Phet Uthai. Then right under the Sirat Expressway but then not sure if there direct access onto the Expressway. I am sure on one occasion I found an access point. I usually finish up going along Rama 9 and pick up the Expressway where is runs very close to the ARL. I think is where the toll booth starts going the other way.

Now I can go through the sois to soi 3 the get on the Chalerm Maha Nakhorn Expressway then pick up the Sirat Expressway.

Is there access from from Thanon Phet Uthai the follow underneath the Sirat Expressway or not. I am sure I did once but I can never seem to find the access slip.