Southeast of El Calafate [1], RN 40 and RP 5 are contiguous as far as El Cerrito, where RN 40 forks southwest toward the Chilean border. At the junction of RN 40 and east–west RP 7, about halfway to Puerto Natales [2], Tapi Aike is a wide spot in the road where there’s a gas station, a convenience store, and accommodations at nearby Estancia Tapi Aike [3].
From here, the road continues southwest to the border crossing at Cancha Carrera, the easiest access to Torres del Paine [4], with occasional direct summer bus connections. Most travelers, though, enter Chile at Río Turbio [5], an otherwise bleak coal town with a historic narrow-gauge railway and a modern ski resort.
Links:
[1] http://www.moon.com/destinations/argentina/southern-patagonia/interior-santa-cruz-province/el-calafate
[2] http://www.moon.com/destinations/chile/southern-patagonia/puerto-natales
[3] http://www.moon.com/destinations/argentina/southern-patagonia/interior-santa-cruz-province/rn-40-south/estancia-tapi-aike
[4] http://www.moon.com/destinations/chile/southern-patagonia/parque-nacional-torres-del-paine/torres-del-paine
[5] http://www.moon.com/destinations/argentina/southern-patagonia/interior-santa-cruz-province/rn-40-south/rio-turbio