The rail link between Thessaloniki and Constantinople, via Alexandroupoli and Adrianople, would never have been accomplished if it had not been of immediate interest to the Turkish army. The existence of an alternative and established shipping route, via Kavala, made a coastal rail line superfluous. Furthermore, the construction problems were not negligible, since the new rail line would have to cut through the marshes in the plain of Serres.
The inadvisability of the project was also apparent from the contract, eventually signed in 1892, by which the Turkish government awarded construction to a French group of companies: it provided for an annual guaranteed reimbursement of 15,500 francs per kilometre over a period of 99 years, more than three times the line's actual income. For obvious military reasons, the line followed a route that was unassailable from the sea: Doirani, Serres, Drama, Xanthi, Komotini, Alexandroupolis.
Its construction proved the fastest of all the Macedonian lines. The project, begun on 22 June 1893, was completed on 1 April 1896. Its importance became evident just one year later: on the eve of the Greek-Turkish War, a Greek armed band landed near Kavala with the aim of mining the tracks but failed to get near them. The speedy transport of Turkish troops decided the course of the war, justifying the expectations of the German-educated Turkish officers.