There are six tolled on/off ramps at Wilson, John Ralston, West Lake Houston, Winfield, Garrett and Tidwell Roads, with a main-lane plaza between West Lake Houston and Winfield. The road has eight free on/off ramps at Mesa, Wilson, John Ralston, West Lake Houston, Winfield, Garrett and Tidwell Roads and US 90. A connector ramp links the toll road to the north and southbound lanes of US 59.
The Sam Houston Tollway is one of the longest continuous loop roads in the country. With the completion of the northeast segment of the Sam Houston Tollway, the Harris County Toll Road Authority's flagship roadway is coming full circle. It will be possible, for those with the inclination, to drive an 88-mile donut around the Houston metropolitan area without stopping.
The concept for a second ring highway began in 1952 when the City of Houston's planning department proposed an outer belt thoroughfare to be located four to five miles beyond the city limits, which were, at that time, where the present-day IH-610 Loop stands.
In 1984, the newly created Harris County Toll Road Authority broke ground on the Sam Houston Tollway. The project was designed to be built in sections as funding and right-of-way became available. In 1994, HCTRA acquired the Beltway 8 Ship Channel Bridge from the Texas Turnpike Authority. The agency purchased right-of-way and constructed frontage roads for Sam Houston Tollway East in 1996, and completed the south section in 1997. The new and final 13-mile stretch will connect US 59 North and US 90 East.