Wednesday, April 25, 2012

Road Header Rendezvous Challenge

A road header travels east from Mission Boulevard at rate of 45 feet per day. A second road header travels west from I-680 at a rate of 35 feet per day. When will the two road headers meet?

At some point, we’ve all scratched our heads and tried to figure out a math problem like that. Here at the SFPUC we won’t ask you to solve word problems. Instead, we invite you to be part of our Road Header Rendezvous Challenge.


In June, miners excavating the new tunnel from the Irvington Portal in Fremont will meet miners tunneling west from the Vargas Shaft. When it happens this hole-through will mark the completion of the Irvington-Vargas tunnel segment.

The chart above has 101 squares each corresponding to a date and timeframe in June when the rendezvous could happen. Your challenge is to figure out the day and time combination. Guess correctly and you could win a prize pack featuring gift certificates to local business and other goodies.

How to Enter
Choose your top three squares and e-mail your choices to fzamora@sfwater.org. Include the date and time you think the hole-through will take place. Squares will be assigned first come, first serve. Only one square is allowed per person.

For example, someone could submit the following:

  1. June 19 between 6:01 AM and 12:00 PM
  2. June 5 between 6:01 PM and 12:00 AM 
  3. June 28 between 12:01 AM and 6:00 AM 

If the first choice is available then the square is assigned to that person. If the square is unavailable then the next available choice is assigned.

Submissions will be accepted until May 31. Please include your name, address, phone number and e-mail so we can contact you if you're successful!

Information to Help You Choose
The tunnel segment between Irvington Portal and Vargas Shaft is 4,500 feet long. As of April 24, miners have tunneled 1,657 feet east from Irvington and 1,810 feet west from Vargas. Ground conditions dictate excavation. In ideal ground conditions, crews have tunneled up to 98 feet in a day. When ground conditions are poor they excavate less than 20 feet. In the last month miners averaged 38 feet per day. Miners do not tunnel on Sundays.



We’ll update the tunnel’s progress every week at www.sfwater.org/nit. Good luck!

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