What Are These Concrete Arrows On Top Of Acalanes Ridge?

The two arrows were once part of a transcontinental guide for airplane pilots

The concrete arrows on top of the Acalanes Ridge Open Space
The concrete arrows on top of the Acalanes Ridge Open Space
A bit of aviation history sits atop the Acalanes Ridge Open Space area near the Lafayette-Walnut Creek border.

Two concrete arrows about 50 feet in length spring from a crumbling concrete base, both pointing northward at slightly different angles.

The arrows plus the base and two concrete "tails" have deteriorated from lack of maintenance and are covered with spray-painted graffiti.

However, the arrows were once part of an important transcontinental guidance system for pilots when they flew at night.

Walnut Creek Mayor Pro Tem Bob Simmons, an avid hiker, got interested in the arrows a couple years ago. After asking around, he finally talked to Open Space Ranger Bruce Weidman, who told Simmons he'd heard the arrows were part of a nighttime airmail system.

Simmons then contacted the state Office of Land Surveys, where an employee there found an article on sometimes-interesting.com that explained everything.

According to the story, the Acalanes arrows were one of about 1,500 such sites laid out across the country from New York City to San Francisco.

They were first installed in 1924 at the request of the Postal Service. They were in full operation until about 1933 when early radar systems started to make them obsolete.

Before radar, pilots flew during daylight hours using visible landmarks to guide them from place to place.

However, pilots couldn't fly at night. The Postal Service wanted to enable their pilots to work in the dark to speed up mail delivery.

So, the transcontinental system was developed with a series of ground-based beacons 3 to 5 miles apart from coast to coast.

Each site had one or two arrows as well as a 50-foot tower with rotating lights. There were also small concrete square called "tails" leading up to the tower and the arrows.

The sites were lit up at night so pilots could navigate their way in the darkness.

It's estimated only several hundred of the beacon sites are left. Most of them are in remote or difficult-to-access locations.

The towers were torn down decades ago, leaving just the concrete base where they were anchored.

It's not known exactly where the two Acalanes arrows are pointed. One appears to point toward Concord while the other points toward Antioch or perhaps Sacramento.

An aging bench, also covered in graffiti, sits near the beacon remains. It appears to have been installed long after the tower was torn down.

To see the arrows, park at the end of Bacon Way, go past the metal barrier and then walk through the gate on your right and onto the dirt trail.

It's an uphill climb, but the arrows are about a half-mile from the gate on the left. There's a short spur trail that leads to them.

C Roberts January 21, 2014 at 01:14 PM
Fascinating! You can get a great look at them via Google maps' satellite view (probably also from other map services).
Robert Train Adams January 22, 2014 at 01:56 PM
I hiked to the arrows yesterday. It was nice to see a piece of history. The views from the spot are spectacular.


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