Concrete arrows near Walnut Creek one of California’s last reminders of pilot direction system

WALNUT CREEK — It was 1944, and Carol Eisenman Clark clearly remembers the beam from the Acalanes Ridge beacon a mile or so away lighting up her bedroom below. It was a reassuring presence for a 5-year-old, even if she didn’t know the beacon’s purpose.

“My mother kept wanting to close the curtains, but I said, ‘No, I like watching the beacon,’ ” said Clark, now 76 and living again in Walnut Creek. “It shone right through the window, and I loved it.”

It wasn’t until years later she learned what “Beacon 1B” did — help airplanes fly through the dark of night. And it was only last April when Clark first ventured up Acalanes Ridge to the spot where the beacon had been, on a city-sponsored “Walk with the Mayor” led by Bob Simmons.

All traces of the beacon and its tower, save some steel mounting braces, are long gone. But a large concrete double arrow, now covered by graffiti and offering no clue to its onetime purpose, still drapes over the crest of the ridge, only slightly visible from the main trail. The arrows point more or less northward.

It is a remnant of the Transcontinental Airway System, a network of about 1,550 concrete arrows built from 1924 to 1931 to help airmail pilots complete nighttime transcontinental flights faster than trains in an era before radar was practical in aviation. The arrows were accompanied by revolving beacons that replaced a ragtag collection of bonfires and burning oil drums. The project was initiated by the U.S. Postal Service and the U.S. Commerce Department’s Bureau of Air Commerce.

An estimated 200 of the arrows remain today, varying in condition from good to poor, but the Acalanes Ridge arrows are believed to be the only mostly intact set still found in the Bay Area. The exact number of survivors isn’t known, even in the Google Maps era, likely because most that are left are in rural or otherwise lightly trafficked areas — though one graces a front yard southeast of Minneapolis.

“Finding them is usually a matter of getting into a vehicle and looking for them firsthand,” said pilot Patrick Wiggins of Utah, who shares his knowledge of the concrete arrows as part of NASA’s Ambassadors public outreach program.

The arrows, from 50 to 70 feet long and usually painted bright yellow for visibility, were about 10 miles apart on average, depending on whether the terrain was flat or mountainous. They guided open-cockpit biplane pilots along established routes on an 18,000-mile national mail-delivery network. The original route, from San Francisco to New York City, was nicknamed the “Highway of Light” and roughly followed the present-day path of Interstate 80, especially in the West.

“I started flying in the 1960s, and I thought the navigation (technology) back then was crude,” Wiggins said. “But then I learned about the arrows. … They weren’t ever mentioned in aviation school.”

The beacons were usually mounted on 50-foot towers atop each arrow — though beacons built after 1931 weren’t accompanied by arrows. Also at each arrow/beacon site was a small shed with a generator and bearing that station’s identification number.

The Walnut Creek arrows are distinctive, being double-shafted and double-pointed because two national mail routes — Los Angeles to Seattle and San Francisco’s Chrissy Field to Chicago — passed over this spot.

Tom Johnson, of Walnut Creek, a member of the San Carlos-based Society for Aviation History, said one arrow pointed to “Beacon 2,” which used to be on the hill north of Highway 4 between Clyde and Bay Point. The other, Johnson said, guided pilots to an airmail landing strip in Concord, which once existed just north of the current-day Clayton Road/Treat Boulevard/Denkinger Road intersection. It closed in 1940, and no traces of it remain in this residential neighborhood.

After radar and other technology rendered the Transcontinental Airway System largely obsolete, the arrows and beacons started their slow fade from the scene. Some of the beacons were turned off or even destroyed during World War II so as not to aid enemy pilots or vessels, but most survived until at least 1950. It is uncertain exactly when the Walnut Creek beacon was dismantled, Johnson said, but he believes it was about 1950.

“It was still working in 1945, and was gone by 1959,” Johnson said.

The last beacon was officially decommissioned by the Federal Aviation Administration in 1973. Control of 17 beacons was turned over to the state of Montana, and those remain operational to this day, providing extra help for pilots flying over mountains on a lowercase “f”-shaped network between Missoula and Bozeman and between Great Falls and Monida Pass, near Dillon. None of the Montana beacons is accompanied by an arrow anymore.

Most of the arrows succumbed to the ravages of time and weather, vandalism and the encroachment of development. The Walnut Creek arrows are among the last survivors of approximately 125 in California, many of them along what are now interstate or U.S. highway routes.

Others intact arrows still exist just off Interstate 15 east of Baker in San Bernardino County; just west of Interstate 5 near Gazelle, north of Weed; and just outside Montague, east of Yreka. Two others are located just across the state line west of Reno and west of Fernley, Nevada, near Clark.

In the Bay Area, besides the Walnut Creek and Clyde installations, others used to exist near the intersection of Rincon Avenue and Sunset Drive in Livermore; near Clarepoint Way and Knoll Ridge Way in Oakland (there until at least 1959; a partial, deteriorated arrow is still there); along Story Road a few hundred feet east of Highway 101 in San Jose; and in what’s now the Monte Bello Open Space Preserve in the hills west of Cupertino (the intact beacon tower, which Johnson said is the last in the Bay Area, now hosts communication antennas).

Bruce Weidman said relatively few people visit the Acalanes arrows — accessible off Springbrook Road and Bacon Way — and even fewer know its history.

“I had no idea what that concrete slab was the first 12 years I worked here,” said Weidman, a Walnut Creek open space ranger. “My first thought was that it was artwork using extra cement from the Highway 24-680 construction work (in the late 1990s).”

William and Karnen Macera, of Walnut Creek, were hiking the Acalanes Ridge last week, and said they had seen the arrows on three or four previous hikes.

“They were all painted on with graffiti, and I didn’t know what they were, probably some kind of aerial marker,” William Macera said. “I thought, maybe it’s showing the nearest coast.”

When told of its history, the Maceras were delighted. “It would be good to keep it as a historical site,” Karnen said.

Karen Majors, president of the Walnut Creek Historical Society, agrees. She expects a campaign soon to get the Acalanes arrows listed on the National Register of Historic Places.

“At the very least, there should be a local landmark,” she said. “This system was pretty aggressive for its time.”