Dear Dr. Gridlock:

I noted the letter about the crowded four-car trains on Metro's Blue Line, and Metro's response that the Blue Line is the "least crowded" [Dr. Gridlock, June 30]. Metro has been saying that for years, and it's just plain wrong.

Metro apparently counts the number of people using the various subway lines only at the last stop on each line.

It is true that by the time a Blue Line train gets to Springfield, there are relatively few passengers left on board, compared with, say, the number who ride the Orange Line all the way to Vienna. But what about the intermediate stops?

The Blue Line disgorges most of its Virginia passengers at the Pentagon, Pentagon City and Crystal City stations, and in Alexandria. Those passengers don't get counted using Metro's last-station counting method.

Anyone who actually rides the Blue Line knows that between downtown Washington (say, McPherson Square) and the Pentagon, it's absolutely packed; in fact, it's impossible for anyone except maybe a linebacker even to board a four-car Blue Line train at Farragut West. But of course, the people who count passengers and allocate cars for Metro never actually ride the trains!

Lynda Meyers

Arlington

Metro does count customers from the most crowded points on the line, according to Lisa Farbstein, Metro spokeswoman. The Blue Line count is taken at its most crowded station, which is Rosslyn.

The staff tallies the numbers according to passengers per car. By that count, here are the most heavily traveled lines, from most crowded to least:

* Green Line (103 passengers per car);

* Orange Line (96);

* Yellow Line (96);

* Red Line (91);

* Blue Line (86).

The Blue Line now has four-car trains. This fall Metro is to begin receiving the first of 184 new cars that will be dispersed through next year.

The first priority, Farbstein told Dr. Gridlock, is to upgrade four-car trains to six-car trains. Then some trains will be expanded to eight-car trains. By the end of the new deployment, about a third of the fleet will consist of eight-car trains.

Trucks Aren't Truckin'

Dear Dr. Gridlock:

I drive from Gainesville to Warrenton daily on Route 29. The speed limit on this stretch of road is 55 mph most of the way, and the travel time usually is less than 20 minutes.

Lately, however, I've noticed an increase in the number of construction vehicles and dump trucks on the highway. Many mornings the trucks can be found occupying both lanes, traveling around 40 mph, with no intention of turning onto a side street or changing lanes.

Are trucks allowed to travel below the posted speed limit on Route 29 in the left lane?

If they're all traveling at the same slower speed, they should do so in the right lane so commuters can pass them on the left.

Jason Smolinski

Gainesville

Unless signs are posted prohibiting trucks from the left lane, as on the Capital Beltway, I believe they can use that lane. However, there is a Virginia law that if an overtaking vehicle signals an intent to pass, the slower vehicle must pull to the right and let the overtaking vehicle pass.

Of course, if you're honking at truck drivers, that might get you crunched between two dump trucks.

The construction vehicles are another sign that your supervisors are irresponsibly approving more development that will attract more drivers who will need more road capacity that isn't there.

Transportation researcher Diane Mattingly contributed to this column.

You can write to Dr. Gridlock at 1150 15th St. NW, Washington, D.C. 20071. He prefers e-mails, at drgridlock@washpost.com, or faxes, at 703-352-3908. Include your full name, town, county and day and evening telephone numbers. Dr. Gridlock cannot take phone calls.