Worst traf­fic, and worst anx­i­ety

The Washington Post Sunday - - METRO - Dr. Grid­lock dr­grid­lock@wash­post.com.

Dr. Grid­lock looks at a new gauge of ter­ri­ble traf­fic that mea­sures a driver’s an­tic­i­pa­tion of the com­mute and finds that D.C. is most aw­ful here, too.

ROBERT THOM­SON Re­searchers at the Texas Trans­porta­tion In­sti­tute, who keep re­mind­ing us that the cap­i­tal re­gion has the worst traf­fic in the na­tion, have come up with a new way to mea­sure the pain. They call it the Plan­ning Time In­dex and rank us most aw­ful by this stan­dard, too.

Plan­ning time is the buf­fer that drivers think they must build in to as­sure an on­sched­ule ar­rival for pri­or­ity events. The in­sti­tute sets a high stan­dard: How many ex­tra min­utes you would add to guar­an­tee an on-time ar­rival 19 out of 20 days.

I fre­quently see th­ese per­sonal cal­cu­la­tions show up in “Dear Dr. Grid­lock” let­ters, and I re­mem­ber them be­cause they’re dif­fi­cult to an­swer. An An­napo­lis res­i­dent tells me she has a flight from Dulles at 7 o’clock on a week­night, so what time should she leave home?

I’m very con­ser­va­tive in an­swer­ing such let­ters, to the point where the trav­eler would reach the air­port in time to or­der a full meal and a cus­tom­made suit.

The trans­porta­tion in­sti­tute’s in­dex is an over­all mea­sure of the un­re­li­a­bil­ity of trips in con­gested ar­eas.

The PTI for the D.C. area is 5.72, mean­ing a very pru­dent trav­eler would al­low al­most two hours for a high­way trip that would take 20 min­utes in light traf­fic. Want to travel faster and cal­cu­late less? Con­sider mov­ing to Pen­sacola, Fla., where the PTI is 1.31.

Traf­fic plan­ners and engi­neers of­ten re­fer to the anx­i­ety-re­duc­ing add-on as “buf­fer time.” Deal­ing with it is be­com­ing more im­por­tant to trav­el­ers.

On a small scale, you can see this when you ask Google Maps for di­rec­tions. The re­sults show you the miles for the trip and the amount of time it would take in or­di­nary traf­fic. A sep­a­rate list­ing shows you the amount of time the trip will take in cur­rent traf­fic con­di­tions.

When I talk to civic groups, I like to tell them the amount of time Google Maps said it should take me to reach the meet­ing in or­di­nary traf­fic. It al­ways gets a laugh. Then I tell them about the other list­ing for cur­rent con­di­tions and start talk­ing about “buf­fer time.”

Ev­ery­body gets it. In fact, I find it’s the un­re­li­a­bil­ity of trips that bother trav­el­ers more then the length of trips. Still, many don’t use the tools avail­able to plan trips.

Few trav­el­ers tell me they rou­tinely check on­line or by TV and ra­dio to get traf­fic re­ports be­fore leav­ing home.

On a grander scale, the re­duc­tion of plan­ning time is the key sell­ing point for the high-oc­cu­pancy toll lanes now on the Cap­i­tal Belt­way and coming to In­ter­state 95 in Vir­ginia in 2014.

In the­ory: You choose the toll lanes over the reg­u­lar lanes when you need to be some­place on time and are will­ing to pay for a re­li­able trip. The toll rises when needed to main­tain a steady flow of traf­fic. The speed limit on the toll lanes and the reg­u­lar lanes is the same, 55 mph. What you pay ex­tra for is the steady pace of travel.

Drivers re­main some­what sus­pi­cious of this con­cept, but they’re very in­ter­ested.

I think th­ese sorts of time-is­money cal­cu­la­tions are go­ing to be­come a big­ger part of com­mut­ing, whether they are mea­sured by a na­tion­wide in­dex or by the price of us­ing the Belt­way HOT lanes at rush hour.

What’s your take on the Plan­ning Time In­dex? You prob­a­bly use a less ex­treme mea­sure for your own com­mute, but I’ ll bet you do some sort of cal­cu­la­tion in­volv­ing the value of be­ing on time and the an­noy­ance of be­ing early or late. What high­ways are the least re­li­able?

And wouldn’t you also like to see an in­dex that mea­sured the re­li­a­bil­ity of tran­sit travel? The sell­ing points for rail travel once in­cluded the like­li­hood that you would reach your des­ti­na­tion on time. There were sched­ules.

Many com­muters write to tell me they no longer feel they can plan a Metro­rail trip with that as­sur­ance. And they aren’t talk­ing about rel­a­tively rare events like the Green Line shut­down on Jan. 30. They mean all-too-com­mon oc­cur­rences such as trains go­ing out of ser­vice, or switch prob­lems, or trains too crowded to board. Dr. Grid­lock also ap­pears Thurs­day in Lo­cal Liv­ing. Com­ments and ques­tions are wel­come and may be used in a col­umn, along with the writer’s name and home com­mu­nity. Write Dr. Grid­lock at The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or e-mail


Trav­el­ing around Washington can take min­utes, or hours, de­pend­ing on time of day and traf­fic con­di­tions. A new in­dex says com­muters here have to build in the great­est amount of flex­i­bil­ity in their travel plans to get to des­ti­na­tions on time, com­pared with any other metro area.

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