GL: BURLINGTON NORTHERN SANTA FE RR BRIDGE MM 300.5 ON THE ILLINOIS RIVER

[George Grafer]

WE MADE IT UNDER THE BURLINGTON NORTHERN SANTA FE RR BRIDGE ( MM 300.5 ON THE
ILLINOIS RV.) WITH PLENTY OF ROOM TO SPARE. THANK YOU ALAN.

NOTE THAT SKIPPERS BOB BOOK IS NOT COMPLETELY ACCURATE NOR IS THE LOCKTENDERS
@ THE LOCKPORT LOCK WHEN THEY SAY THE CLEARANCE IS 19'1".

ALAN LLOYD'S BOOK , GREAT CIRCLE NAVIGATION NOTES STATES THAT THE CLEARANCE IS
BASED ON 578' POOL LEVEL & THE U S ARMY CORPS OF ENGINEERS CHARTS OF THE
ILLINOIS (NEWEST EDITION)  STATE THAT THE LOW STEEL OF THE BRIDGE IS 597.1',
THIS IS CORRECT.

TO CALCULATE THE BRIDGE CLEARANCE ON THE DAY WE TRAVELED UNDER IT

O'BRIEN LOCK MM 326.4 ELEVATION 577.6' ( GO TO
http://www2.mvr.usace.army.mil/WaterControl/new/layout.cfm ROCK ISLAND DIST.-
IL RIVER BASIN   Illinois River at O'Brien Lock and Dam )
LOCKPORT LOCK MM 291 ELEVATION 575.46'   Illinois River at Lockport Lock and
Dam (POOL)
SUBTRACT ONE FROM THE OTHER ( 2.14') AND YOU HAVE THE DIFFERENCE IN WATER
LEVELS.
THE RR BRIDGE IS ABOUT I/3 THE DISTANCE UP STREAM FROM THE LOCKPORT LOCK. SO
1/3 OF 2.1' IS .71.
ADD THIS TO THE WATER EL AT LOCKPORT 575.46' +.71' = 576.17'. THIS IS THE
WATER EL. AT THE RR BRIDGE THE DAY WE CALCULATED IT.
WITH THE BRIDGE CLEARANCE AT 597.1' - 576.17 ( THE WATER LEVEL)  = 20.93',
JUST UNDER 21' AIR DRAFT.

WITH OUR AIR DRAFT OF 19'1" WE MADE A TICKLER POLE TO THE HEIGHT 19'4" TALL OF
3/4" PVC & MOUNTED IT IN THE BURGEE HOLDER IN THE FRONT OF THE BOAT TO BE SURE
WE WERE ABLE TO GET UNDER THE BRIDGE. I COULD SEE WE HAD ABOUT 18" CLEARANCE.

YOU WILL HAVE TO MAKE YOUR OWN CALCULATIONS ON THE DAY YOU TRAVEL.

HOPE THIS HELPS ALL WITH THE RR BRIDGE AIR DRAFT.

GEORGE GRAFER
TIME OUT
43 MED YACHT
CURRENTLY @ JOLIET, IL

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