Starts & Stops

Trying to follow — and read — the signs

The signs have not always been reader friendly, including this one on Interstate 95 near the Massachusetts Turnpike. (Jonathan Wiggs/Globe Staff)
The signs have not always been reader friendly, including this one on Interstate 95 near the Massachusetts Turnpike. (Jonathan Wiggs/Globe Staff)Credit:

Weekend warriors who head out to the Cape and the Berkshires have likely noticed some new additions to the state’s major thoroughfares: new electronic information signs.

The 48 signs debuted just before Memorial Day, and are positioned at stops on or near the Pike, Route 3 between Braintree and Plymouth, and Route 6 from Orleans to Bourne. The same signs have been posted on I-93 for almost a year.

This new set cost $2.2 million and were paid for with tolls and money from the state.

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“Isn’t this a waste of dollars?” wrote Nancy of Bourne, after spotting them on the highway.

Mike Silvia from Reading had a different take.

“I think it’s great that they’ve put info boards on the highways,” Silvia wrote. But, he continued, “I’ve noticed that they are often just plain wrong.”

“Last week, before leaving Reading [on I-93] for Boston I checked Google Maps, which showed ‘all green’ from Reading all the way to Braintree,” he said. But when he arrived at Medford, the information sign said it would take 32 minutes to travel the eight miles to Exit 28.

“We decided to trust Google,” Silvia said, “and sailed right through the city.”

So, what accounts for the difference?

The MassDOT signs detect Bluetooth signals emanating from mobile devices in passing cars. Each signal is assigned a unique ID number. Sensors track the amount of time it takes for a signal to pass two of the signs on a stretch of highway. An algorithm determines the expected travel time.

According to Mashable, Google uses similar technology for its own real-time traffic data: The company tracks travel times of Android phone users to determine how fast traffic is moving, and also mines data from a mix of third-party vendors. (For example, the company just acquired a smart phone app developer, Waze, that allows users to create a real-time traffic database that can be shared with friends and family, along with the rest of the world. Think: “Fender bender . . . totally stuck in left lane!”)

So the two systems have different sources for their data.

And then sometimes the signs are accurate — you just can’t see them.

A commuter noticed a doozy along I-95 southbound, near the Mass Pike interchange — “smack in the middle of a tree,” she wrote.

I e-mailed MassDOT spokeswoman Sara Lavoie about the tree. A few hours later, she responded.

“We have trimmed the tree,” Lavoie wrote in an e-mail, “and will be sweeping the entire system to make sure all boards are visible.”

Well, that was easy.