My DOT post of 14 Sep 2005 favoring Central Time for Indiana

Title: Time Zone Boundaries in the State of Indiana
Docket: OST-2005-22114-130

To: Joanne Petrie
via "http://dms.dot.gov/submit/"
Office of the General Counsel (C-50)
400 7TH ST SW
WASHINGTON DC 20590-0001


PETITION FAVORING CENTRAL TIME (supplement)
===========================================
I have noticed that quite a few proponents of Eastern time express a concern that it would not be worthwhile observing Daylight Saving Time if Indiana is in the Central zone.

This is certainly a valid concern that deserves evaluation against solid facts. I find that it is helpful to compare how much additional evening daylight we would have on Central Daylight Time with other places in the country that are about midway between the middle and eastern edge of a standard time zone, like Indiana.

Indianapolis is a handy city to use for reference, since it is almost exactly the geographic center of Indiana, as well as the state capitol. According the the U.S. Naval Observatory website, the longitude of Indianapolis is 86.13 degrees. This puts us 3.87 degrees east of the nearest standard time zone meridian, which is at 90 degrees (Central time). The other standard time zone meridian lines for the continental U.S. are at 75 (Eastern), 105 (Mountain), and 120 (Pacific).

Being 3.87 degrees east of the nearest meridian means that the sun sets in Indy about 15 minutes earlier than at the center of the nearest standard time zone. Other major U.S. cities which are also located 10 to 20 minutes east of their nearest standard time zone meridian include Spokane WA (10 minutes east), Nashville TN (13 minutes east), Boston (16 minutes east), and Las Vegas (19 minutes east).

The following table illustrates the additional number of minutes of daylight each of these comparably-situated cities enjoys after noon than before, for four representative dates in 2006. The sunrise and sunset times used to make this calculation are from the U.S. Naval Observatory website (with one hour added for Daylight Time April through October).

http://aa.usno.navy.mil/data/docs/RS_OneYear.html

The first date (January) is mid-winter, about midway through the standard time period. The following three dates are representative of the beginning (April), middle (July), and end (October) of the daylight saving time period. On January 15, although the evening and morning daylight is about equal, the parentheses indicate that there are a few more minutes of sun in the morning than in the evening that time of year (when not observing Daylight time).

MORE MINUTES OF SUN AFTER NOON THAN BEFORE

1/15 4/15 7/15 10/15
===== ===== ===== =====
Spokane WA (2) 100 110 70
Nashville TN (7) 95 105 65
Indianapolis (12) 90 101 60
Boston (12) 90 100 60
Las Vegas (19) 82 93 53

As the table shows, the facts give little basis for concern that Indiana will not still receive the benefit of significant additional evening sunshine while observing Central Daylight Saving Time (just as we effectively have for the past few decades on EST). Daylight Saving Time gives a substantial shift of daylight from morning to evening throughout the daylight saving period.

The amount of extra evening daylight is in the same general range enjoyed by other areas of the U.S. which are also located midway across the eastern half of a standard time zone like Indiana.

In fact, the table shows that the benefit to Indiana from Daylight Saving on Central time is nearly identical to that of Boston on Eastern time (which lies almost exactly one full standard time zone -- 15 degrees -- to our east). I don't see anything in the news about Boston's wanting to be in the next time zone to its east (Atlantic Time) because it doesn't think it's getting enough benefit from Daylight Time.

Sincerely, Bill Starr
Bartholomew County resident
14 Sep 2005

My DOT post of 14 Sep 2005 favoring Central Time for Indiana