| State Highway Spur 78 | ||||
|---|---|---|---|---|
| Route information | ||||
| Maintained by TxDOT | ||||
| Length: | 1.547 mi[1] (2.490 km) | |||
| Existed: | Before 1939 – present | |||
| Major junctions | ||||
| South end: | Mt. Locke summit, McDonald Observatory | |||
| Spur 77 | ||||
| North end: | SH 118 | |||
| Location | ||||
| Counties: | Jeff Davis | |||
| Highway system | ||||
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Highways in Texas
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Texas State Highway Spur 78 or Spur 78 is a spur road maintained by the Texas Department of Transportation (TxDOT) connecting the University of Texas at Austin's McDonald Observatory complex atop Mt. Locke to State Highway 118 15.2 miles (24.5 km) from Fort Davis[2]. The road is 1.5 miles (2.4 km) long and is located within Jeff Davis County.
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Spur 78 was not included on the 1933 official state highway map[3], but was in existence by 1939 when both the observatory was dedicated[4] and the state's Highway Designation Files were created[1]. Before 1941, the road connected the observatory to SH 166 until the section of that route between Fort Davis and the current intersection of SH 118 and SH 166 was re-designated as part of SH 118[5]. In 1991 the only other intersecting highway, Spur 77, was created[6].
At its terminus at the summit of Mt. Locke, Spur 78 has the distinction of having the highest elevation at any point on the state highway system with an elevation of 6,791 feet (2,070 m)[7]. The route begins in front of the Otto Struve Telescope and Harlan J. Smith Telescope where there is a scenic overlook of the valley below and the surrounding Davis Mountains.
Initially the route has steep grades as it descends from the summit of the mountain. After 0.5 miles (0.8 km) the route intersects Spur 77 toward nearby Mt. Fowlkes where the observatory has another cluster of facilities. Spur 78 also intersects a few observatory service roads to maintenance facilities and residential areas. The observatory passes by the observatory's Frank N. Bash Visitors Center before terminating at SH 118.
The entire route is in McDonald Observatory, Jeff Davis County.
| Mile[8] | Destinations | Notes | ||
|---|---|---|---|---|
| 0 | Mt. Locke summit | Southern terminus | ||
| 0.5 | Spur 77 | Mt. Fowlkes spur | ||
| 1.5 | SH 118 | Northern terminus | ||
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi | ||||
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