EVERY TIME I ride past the stretch of Highway 101 where it happened, I imagine it happening all over again. Traffic suddenly slowing down in front of me as I am merging. I brake too late.

It was my first accident. My only accident, since I haven't driven since.

The insurance company told me, almost apologetically, that it was 100 percent my fault. It's more like 200 percent.

I should have taken BART to visit my friend, instead of driving. But he didn't have a car to pick me up from BART. He would have needed to ask his friend to get me, and I wanted to spare him the inconvenience.

I should have left earlier, before traffic got heavy.

I should have filled up on gas at a station near my house. Instead I had to get off the freeway, get gas and then get back on and merge into the correct lane.

I should have paid more attention to the traffic, with its cyclical accelerations and slowdowns.

I should have paid more attention.

I don't remember the crash. I swore, wide-eyed, as I slammed on the brakes and then stared in shock, past a deflating air bag and through an intact windshield, past a crumpled hood, at the car I'd stopped by running into its rear end.

The CD player was still playing They Might Be Giants. I turned it off.

I hope you never see that smoke in the cabin of your car. Ultrafine powder is packed inside the airbag canister to lubricate the cloth and help it deploy in milliseconds. I hope you never have to smell it, or wash it out of your hair and your clothes. I smelled that acrid stuff for hours, till I could get home and shower.

I called 9-1-1, got a passing tow truck driver to tow the car to the shoulder and exchanged information with the other driver, all in disbelief. I hadn't been drinking or talking on a cell phone. We were lucky; no one was hurt, except for a bruise on my wrist where the airbag had blown past. My wrist hurt, and my heart hurt. How could I have done this?

Half-remembered legal advice stopped me, a hundred times, from telling the other driver that I was sorry. She could take it as an admission of fault and use it as evidence against me and my insurance company, I thought. I'd never been in an accident before. I didn't know what to do.

Another piece of luck: All the systems worked flawlessly. The 9-1-1 dispatcher told me to take deep breaths and speak in a lower register to calm down, and it worked. The tow truck drivers were efficient and friendly. The CHP officers reassured me that a no-injury, fully-insured collision was far from the worst that could have happened.

The insurance agents and claim processors led me through the process kindly and professionally.

That user-friendly process almost angered me. Getting preventive care or a prescription takes appointments, forms, faxes, fees and endless runaround, but the post-accident procedure is beyond user-friendly. It's idiot-proof. I ranted that this unfairly rewarded idiots. Idiots like me, who didn't pay enough attention on the highway.

The car was totaled. I wrote to the other driver, apologizing profusely. She didn't write back. I became more forgiving of minor errors, then forgot my new humility. The leaves turned, and I turned the leaves of my calendar.

I haven't driven since.

Suddenly I am a difficult passenger on the highways, cringing whenever we follow fewer than three car lengths behind someone, inhaling audibly as we pass big rigs. Fearful flyers get told that flying is safer than driving; what bromide can I use?

I think I could drive on surface streets. Where stop signs, pedestrians, stoplights, oncoming traffic and narrow streets call for the driver's attention, I'd feel secure.

But where motorcycles and semis and SUVs and sedans dance at 60 mph, I took a moment to move left instead of slowing down. I ruined a car and two people's days.

In the next decade, as gas prices continue to rise, America will stop taking driving for granted. I got there early, jolted out of complacency and into an ugly nightmare of my own design, in the No. 2 lane of 101 North.

Sumana Harihareswara writes for Bay Area Living each week. Please send comments to sumana@crummy.com.