Navigation system can help cut stress
The morning commute was going well: I was seeing orange, not red. According to the map on my console-mounted computer screen, that meant the traffic flow ahead was ''moderate," moving at between 27 and 52 miles per hour, from Route 3 in Hingham to the Southeast Expressway.
I was midway through a six-day test of a $50,000 Acura RL outfitted with a navigation system and a real-time traffic display. My daily drive, from Plymouth to Boston, offers plenty of real-time traffic challenges. It can take 40 minutes, or 2 hours.
The Acura manual advised against looking at the screen while driving. Such curiosity could cause ''a crash in which you could be seriously injured or killed," it said. I suppose that means drivers should monitor traffic only when they are not in traffic. But it was impossible not to fiddle with this high-tech tool designed to help me steer clear of clogged arteries and snarled side streets.
An RL television commercial makes the navigation/traffic system appear miraculous: A blissful Acura owner motors along an empty road parallel to a crowded freeway. He has found a ''blue" street -- one with ''free-flowing" traffic (at least 52 miles per hour), while everyone else overheats themselves and their engines. The advertisement doesn't speculate on what will happen if onboard traffic monitors become popular and everyone pulls onto the blue road. We'd all be in the red, I suspect -- that's the color the system uses to indicate speeds between 0 and 27.
My experience was less dramatic than the TV fantasy -- there is no secret way to bypass the expressway, the Braintree merge with Route 3, or the lane drop before Route 228. Overall, the system did provide helpful information, and it seemed fairly accurate. Knowing what was ahead may not have prevented me from eventually joining a sea of brake lights, but it did help moderate my stress levels.
The navigation part of the RL system is standard. It charts directions using global positioning satellites, a map database, and gyroscopic and speed sensors in the car. It can be operated by using an interface dial or voice-activated commands. A pleasant voice issues periodic prompts such as ''In a half mile, make a right turn."
The traffic feature is more novel. And for now, its scope is limited. At the time I drove the Acura, coverage areas included Boston, plus major routes in Essex, Middlesex, Norfolk, and Worcester counties. Parts of Cape Cod and the Springfield region also have coverage, as do Manchester and Nashua, N.H., and Burlington, Vt. Nationwide, about 20 major cities have real-time traffic displays.
My commute route was covered only from Route 3 on the Hingham-Rockland line to Boston, less than half of the driving distance. Secondary roads did not appear to have any real-time information.
The system relies on road sensors and manual monitoring of police and emergency scanners to calculate traffic flow. Additional sensors -- and perhaps cellphone signals -- will make such traffic systems more inclusive.
On-screen data are continually updated to create the colored ribbons that track traffic speed. The system also features icons indicating the locations of accidents, work crews, and significant weather conditions. By clicking on one, more detailed information is displayed, a feature I found useful. For example, I was able to squeeze past a left-lane accident in Braintree by keeping to the right because the computer screen had notified me of it 15 minutes earlier.
A few days later, though, it was back to my Honda Civic. I was once again relying on radio reports and skillful lane-shifting, feeling a bit blue and driving red.
Mark Pothier can be reached at mpothier@globe.com. 
