D4 PPP (Czech Republic's earlier highway PPP)
The D4 was an earlier Czech highway public-private partnership using the same design-build-finance-operate-maintain model now applied to the D35. The D35 project explicitly builds on this precedent, with one key difference: preparatory works can begin immediately upon contract signing, whereas the D4 required a longer lead time.
The D4 established the PPP framework for Czech highway construction, with the state paying availability fees only after sections open.
It created the template the D35 now follows, testing whether the PPP approach can scale to the country's biggest transport project.
The D35 is the second and much larger application of the D4 model, with the Ministry of Transport noting the streamlined preparatory works process as a direct improvement.
