All-electronic tolling via E-ZPass transponders hsa become more widespread since the 495 Express Lanes opened in 2012. (Dayna Smith/For the Washington Post)

Dear Dr. Gridlock:

Are you aware that E-ZPass transponders do not last forever?

E-ZPass notified us by mail after my car got three unpaid toll charges, so I called and found out the transponders have a limited battery life. My transponder was 13 years old.

We have used it on road trips and love it. But my transponder hadn’t been functional since July. E-ZPass didn’t have my newer car’s tags, either. Were you aware that if you get a new vehicle, you need to notify E-ZPass?

So I went to [the E-ZPass Stop-in Center at] the Motor Vehicle Administration to get my new transponder for $7.50. Now, how long do I wait to replace this one?

Elaine Newman Miller, Silver Spring

DG: I’ve had E-ZPasses since the early 1990s, just about as long as this electronic tolling system has existed, so I get what the letter writer went through. I think I’m on my third transponder now, after replacing them each time the batteries wear down.

The system is expanding, and so are the uses of electronic tolling. It used to be that all transactions occurred at slow speeds in toll plazas, where drivers usually got feedback from a signal that would warn of a low battery or display a red light.

Today, many highway agencies offer the option of all-electronic tolling. Drivers going at highway speed pass under a gantry that records the toll. It’s safer and more convenient than slowing for a toll plaza.

But the gantry provides no feedback to the driver about the state of the transponder. I’ve heard from drivers who want that, but I haven’t seen a safe way to provide the feedback without distracting drivers while they travel at highway speeds.

In the Washington region, the odds of encountering all-electronic tolling have increased with the addition of the Intercounty Connector and the I-95 Express Toll Lanes in Maryland and the high-occupancy toll lanes in Virginia.

With Thanksgiving approaching, many local drivers will head to the Northeast, where they may encounter all-electronic tolling options in Delaware, New Jersey, New York and beyond.

Since last Thanksgiving, the Tappan Zee Bridge over the Hudson River has gone to cashless tolling. Drivers either pay via E-ZPass or the system records an image of the vehicle’s license plate so a toll bill can go out in the mail.

If your E-ZPass battery is wearing out, and the E-ZPass system can’t associate your license plate with your account, the system may not know where to send the bill, and you might wind up having to pay penalties. So don’t forget to update your E-ZPass account when you get new license plates. If you use a credit card to maintain your account balance, make sure to update the account information when the credit card expires.

The E-ZPass battery is sealed inside the transponder. You can’t replace the battery yourself, but it should last about a decade before you need to replace the transponder. There are more than 30 million transponders in use, and drivers in the Washington region get them from many different transportation agencies.

A few of those agencies send out replacement transponders when they calculate that a user’s transponder is reaching the end of its life. That fits in well with all-electronic tolling, because those users don’t get low-battery warnings.

I hope all the E-ZPass systems, including Maryland’s and Virginia’s, will adopt automatic replacement programs. That’s good customer service.

Dear Dr. Gridlock:

One wonders whether red-light runners could eventually be coaxed into obeying traffic lights?

Maybe all drivers waiting at a traffic light could blow their horns when they see another driver race through a red or even yellow light. I’m quite sure I’ve prevented wrecks by blowing my horn when observing a red-light runner.

On at least one recent occasion, a driver who approached the intersection from my left stopped short, although he had the green light, while a driver overtaking my stopped car and running the light finally woke up and skidded halfway through the intersection. It looked as though a horrible wreck had been avoided by my blowing the horn.

I’d like to encourage you, as Dr. Gridlock, to announce and push a program designed to encourage drivers witnessing red-light runners to blow their horns. One would think that if all who were stopped were loudly heard from, red-light runners would eventually get a strong message of public disapproval, rather than thinking they had pulled off a coup.

Lloyd Young, Annandale

DG: Young’s use of the car horn in that situation is well-intentioned. He’s not describing the sort of obnoxious behavior we’re all familiar with, but a response to a dangerous situation.

Still, I’m hesitant to suggest that other drivers follow his lead. Yes, it might do a lot of good if it gets an endangered driver, cyclist or pedestrian to take notice. But I worry about unintended consequences. Not every traveler will pick up on the intent and respond appropriately. A traveler might even be distracted by the sound of the car horn and look away from the danger.

It might work as a way of registering disapproval at bad behavior. But for that, I’d prefer the flash of an enforcement camera to the honk of a car horn.