First, the tops of the edge girders are aligned, the top splice plate
is then pinned to the edge girder and then bolted in place. Here is a little
Here is Lewis (bottom) Jack (top) and someone else (?) encouraging the
north end to behave itself. Left (before) and Right (after)
Being an iron worker is something else. Jack's acrobatic skills are
So you are probably thinking - how do you adjust the vertical and horizontal
alignment? I watched today and was quite surprise. For horizontal alignment,
hydraulic jacks are used to nudge the deck forward. Vertical alignment is
an exercise in free body diagrams. Fork lifts are used - either with or
without counterweights. They are moved closer to the gap or further away
from the gap - depending on whether you need down or up adjustments. Tomorrow
I'll have some photos of the jack and the fork lifts.
Here is the mobile counterweight on the west deck: Initial position
After moving back toward the west pylon
Here is the mobile counterweight on the east deck: Initial position (left)
and after moving back toward the east pylon (right)
Horizontal alignment is encouraged with these jacks -
that press against a rather large concrete block and frame tied to the deck.
Here is shown the jack before applying hydraulic pressure (left) and after
Wilbur Poole applies turns on the hydraulic pressure
which moves the inner cylinder about 2 inches (right)
To make the jacks do their thing, Wilbur has to switch the pump on,
increasing the pressure in the lines and forcing the jack cylinder out.
To put some size scale - the right photo shows the jack relative to
Wilbur's gloved hand while the right photo shows the team. Peo Halvarsson
(left of kneeling Wilbur) is doing his usual bit of encouragement
The hydraulic jacks do their job and here is the result (about 5:00pm).
Note bolts now fill the top splice
place and drift pins are holding the vertical splice place in position and
the first bolts have been inserted.
A last look at the closed gap
March 10, 2005 Two days later, bolting the north and south
splice plates is complete
This work is licensed under a Creative Commons License.
C. Frank Starmer