WHEN TRAFFIC IS at a standstill – as it is all too often in metro Boston these days – there are big-picture economic and environmental impacts. But congestion can also affect the health of the drivers caught in its throes.

Philip Levendusky, director of the psychology department for McLean Hospital, where he is also co-director of psychology training, says as commutes have grown longer and less predictable drivers often feel a sense of helplessness that often manifests itself in stress-induced tension and even road rage.

Levendusky’s background with traffic-induced stress extends beyond his social science training. Years before his professional study of the human mind, Levendusky worked as a cab driver and as a toll-taker on the Tobin Bridge, where he experienced the brunt of driver rage first-hand.

One of the great ironies of traffic is the individual driver sitting there cursing the cars ahead is just as responsible for contributing to the congestion as they are. But while policymakers debate how to encourage alternatives to driving, how to make roads safer, and how to reduce tailpipe emissions that hasten global warming and can contribute to respiratory or cardiovascular ailments, Levendusky is focused on the psychological wellbeing of the person behind the wheel.

The top psychologist at Massachusetts’s premier psychiatric hospital doesn’t have all the answers, but Levendusky is able to frame what for many is a daily frustration in a mental health context. He says drivers need good coping mechanisms – measures to restore a sense of control – to deal with congestion.

I talked with Levendusky by phone earlier this week. What follows is an edited transcript of our conversation.

COMMONWEALTH: What causes stress when you’re behind the wheel?

PHILIP LEVENDUSKY: Where people have a compromised sense of being in control, that creates a real significant amount of stress. People can experience it in different kinds of ways. Some people break out in sweats. Other people become demoralized. Other people will do challenging driving strategies.

CW: What causes those feelings of a loss of control?

LEVENDUSKY: You want to be at a place by a certain time – you’ve set up your schedule for the day to accomplish that. Or day in and day out, you’ve got to be at work at a certain time. And when the traffic grows to the degree that it is now, you’re constantly in a situation where you get in the car and you don’t have any idea how long it’s going to take you to get to work. People like to have some predictability and control in their lives. And when you’re on a road with 5,000 cars ahead of you and 5,000 cars behind you, and the best you can do is to move when they move, you feel impotent in terms of being able to do anything about it.

CW: How does that uncertainty and the stress that it causes manifest itself physically?

LEVENDUSKY: You could easily see a person starting to hyperventilate. Everybody’s got a different kind of physiology and biochemistry when it comes to stress situations. If they’re the type of person who is a grip-the-wheel kind of driver, there’s the tension that they’re putting on their hands and their arms. A person could have the uncontrollable need to scream, swear, what-have-you to try to relieve the stress that they’re experiencing. What everybody does do is have some kind of physiological reaction and psychological reaction when they are stuck and feel like they can’t get out of it.

CW: Can you do anything to ease the stress when you’re in traffic?

LEVENDUSKY: The approaches that I’ll talk to people about are: What are the things I can do in the cab of my car that allows me to at least do some kind of control? Listen to the radio or books on tape, or call friends, but something that allows me to cool down and depressurize myself.

CW: If you’re a bus rider, and to a lesser extent if you’re on a Green Line trolley, you’re also affected by this traffic. Of course, you’re not behind the wheel.

LEVENDUSKY: Without question. There are people who don’t like to use public transportation because they know they’re not controlling it. They don’t know when the train’s going to come. They don’t know what’s going to happen on the train. So it’s one more step out of being able to really control the situation that you’re in.

CW: You must have encountered a lot of drivers when you were a toll-taker. Did you notice anything back then that you still think about today?

LEVENDUSKY: I worked on the Mystic River Bridge for the Port Authority for a year or so. So I’m a toll collector and people when they were in a long-long line, I got first-hand. They didn’t spit at me or anything like that, but ‘Here [angry grumbles]’ as they give me the 25 cents or whatever it was. That was an up-close and personal view of otherwise perfectly normal, reasonable people with steam coming out of their ears, because they were stuck. Their sense of control was compromised, and they were feeling a mini version of what we’re feeling day-in and day-out now.

Philip Levendusky

CW: This is a little outside your area of expertise, but we both know that stress can contribute to cardiovascular problems, and you just said that all this traffic and the uncertainty it creates causes stress. Do you think, therefore, that traffic is leading to hardened arteries and that sort of thing?

LEVENDUSKY: I wouldn’t be the person to definitively answer that question, but being in that kind of situation day-in and day-out no doubt has an impact on one’s biological being. And some people are going to have a tendency towards cardiac issues and that kind of situation might trigger it for them. In other people it triggers anger and they relieve themselves by screaming at the car in front of them. But I think the takeaway is constantly being in that situation of not being able to control the fate of your day coming and going to work no doubt impacts people in a physiological way.

CW: You’ve noticed this phenomenon over the years, but is anyone studying it?

LEVENDUSKY: I was trying to come up with some stuff knowing we were going to talk. I didn’t put a lot of time in it, but nothing jumped out at me.

CW: What would you prescribe for the metro Boston driving public to deal with this problem of traffic-induced stress?

LEVENDUSKY: The probability of them avoiding some kind of traffic situation on their way into work is pretty low. Can you work from home a little bit? Can you take the time to look at alternative ways for getting from point A to B?

CW: When you were a cab driver, did you notice anything psychologically about drivers then that maybe you’ve learned a little bit more about in your professional experience?

LEVENDUSKY: I was surprised by the road rage factor. And we’re talking back in the late ‘60s, early ‘70s. There were a lot of people – at a time when the precipitant, I didn’t think, was as high as it is today – who would engage in road rage — give the finger, bump against you while you’re sitting at a stop light. And that cohort was radically different than 98 percent/99 percent of the people that I encountered. On busy days, those were the outliers not the regular ones, but the fact that they even existed surprised me.

CW: Would you say that it’s still a very small percentage of people on the road today?

LEVENDUSKY: No. My impression is the road rage kind of phenomena has grown and is correlated to being stuck in traffic all the time. People who can manage it – and the things that they can do to manage it goes back to how do they use that time behind the wheel in a constructive manner – that probably defuses it. But for some folks, they either don’t know how to do that or the situation is just so demanding that it won’t neutralize the angst they’re experiencing.

CW: Why is it that people who wouldn’t ordinarily yell at people around them, give them the finger, or act aggressively and dangerously, suddenly do those very things when they’re in a car?  What’s that all about?

LEVENDUSKY: Our car is a place that we feel is sacred for many of us. We spend a ton of money on a certain kind of car. The person who’s stuck in traffic in a $65,000 car, they’ve got to be saying there’s something wrong with this picture. And if they have a rage thing – somebody almost bumped into them, somebody cut them off, oh my god they’re going to wreck my car, I’m stuck in this crappy thing – then there goes the finger or there goes my horn.

CW: So it’s just that they want to get a return on their investment?

LEVENDUSKY: We are an auto-erotic population.

CW: That’s auto-dash-erotic.

LEVENDUSKY: Auto-dash-erotic. We like our cars. We talk proudly of the long trips up to northern Maine, all that kind of stuff. For many of us, when the traffic isn’t crazy, we’re sitting in the car and it’s a place to unwind at the end of the day. We can get home and have a pleasant time. I enjoy driving. For all the stuff I was just talking about, I genuinely enjoy being in my car and driving. But when I’m in that kind of circumstance, when I’m paralyzed, I’m not enjoying that.