If the laneway is, as you state, a public road – and therefore not the Owners Corps responsibility – you should ask your local council to send a parking officer round to ticket the truck for impeding access on the road.
NB: Your committee may have decided that as this is a public road it is not their responsibility … but they should have told you that, at least.
If the laneway is common property, apply to Fair Trading for mediation prior to seeking orders under Section 232 (1f and 2) [below], compelling them to take action. You’ll find links for all the forms you need HERE.
232 Orders to settle disputes or rectify complaints
(1) Orders relating to complaints and disputes
The Tribunal may, on application by an interested person, original owner or building manager, make an order to settle a complaint or dispute about any of the following:
(f) an exercise of, or failure to exercise, a function conferred or imposed on an owners corporation under any other Act.(2) Failure to exercise a function
For the purposes of this section, an owners corporation, strata committee or building management committee is taken not to have exercised a function if:
(a) it decides not to exercise the function, or
(b) application is made to it to exercise the function and it fails for 2 months after the making of the application to exercise the function in accordance with the application or to inform the applicant that it has decided not to exercise the function in accordance with the application.