By late 1909, the San Benito Land & Water Company had sold most of its land near the tracks of the St. Louis, Brownsville & Mexico Railway. But due to a lack of all-weather roads, few persons were willing to buy land situated more than a few miles from the tracks. To solve this problem, Robertson decided to construct a feeder railroad. He envisioned two loops of track, one to the north and one to the south of San Benito, so that no property in the lands owned and served by the Company would be more than two miles from a railroad track. Robertson asked B. F. Yoakum to finance the project, but believing the project not feasible, Yoakum declined. Undaunted, in March 1910 construction began on what at first was called the Interurban and commonly known as the Spiderweb Railroad [Historical marker, 1982].
Robertson once again short of cash, Yoakum convinced the St. Louis Union Trust Company to
advance money for payroll. By June 1912, approximately 39 miles of track had been laid, consisting of the loop south of San Benito and approximately one-half of the north loop. 175 Stations, erected every few miles, were small one-room buildings painted yellow, or simple wooden loading platforms. By the summer of 1912, Yoakum had not only changed his mind about Robertson's feeder railroad, he was convinced that the system should be extended into Hidalgo County. Robertson agreed to sell the Interurban to Yoakum. On June 28, 1912, Robertson incorporated the Interurban as the San Benito & Rio Grande Valley Interurban Railway. Soon afterward, a Yoakum controlled syndicate purchased Robertson's stock in the Interurban and changed the name to San Benito & Rio Grande Valley Railroad. By 1928, the Spiderweb had approximately 128 miles of track.