What is a traveler? Here is the temporary traveler used for the
construction - and some guys "constructing". The traveler rides on the lower
lip of the edge girders and provides a platform for cleaning, inspecting
and repairing the underside of the bridge spans.
Specialized Engineered Products (SEP Group) at work:
Here is the traveler -
126 feet long, spanning from one side of the
platform to the other side.
It is a product of SEP which build elevators and travelers that perform
with a bit of magic - as
in going around curves and going uphill and downhill without sliding.
The traveler is a sort of horizontal elevator
that moves along the inner edges of the edge girders. It is used
for cleaning, inspections and maintenance.
This traveler moves at a maximum rate of
60 feet/min but
the usual rate is 15 feet/min. But perhaps the more interesting part
of the traveler is how it maintains its perpendicular alignment with the
edge girders. For example, if the left side travels a bit faster than
the rights side, then the overall traveler is skewed. Think about it
- how would you design the controls to maintain a minimal skew?
The north end of the traveler. The drive assembly rides on the lip
of the lower "I" of the outside edge girders.
The middle of the traveler
The south end of the traveler
According to Murray, "our" Cooper River Bridge traveler is the longest
single unit traveler in the world. It was shipped in three pieces and then
spliced together. It is powered by 480 volt AC motors
and controlled by a computer system.
Murray smiles and declares that he
has the most powerful remote control in the world and can travel the
full distance of the main and back spans with his remote control.
Here is Murray, and the southern end of the traveler with a motor and
gear/wheel drive on the left and on the right (gray boxes).
Here you can see the top of the traveler (black region) and the underside
of the bridge
Here is a view of the drive motor and the lower lip of the
north edge of the bridge
And here is wheel assembly as it rests on the inside and outside
edge girder lips.
Note that the roller uses about
4 inches of the bottom of the edge girder as a track. In the background
you can see the bearning that buffers the movement of the bridge deck
relative to the inner pylon face.
Here is the traveler control box and a view of the computer that is
mostly is chilling out inside
The remote control - how to "call" the traveler when it is stationed
at the east pylon and you are waiting on the west pylon.
There are four elevators, one for each inner face of each pylon.
The elevators are interesting because not only do they travel up
and down following the incline guide rails, but at the level of the
pylon crossbeam, the incline reverses.
The channel that wraps around the cab has a pin supporting the cab and
permits the elevator cab to maintain vertical alignment similar to a
Here, the elevator is at the lower level (basically a 3 stop elevator:
pylon crossbeam / traveler level, the main deck and the top.
Here is the view of the bottom of the pylon shaft - looking up from
the base of the pylon. The box is the elevator shaft passing through
the pylon cross member.
A view of the elevator coming up
Here the elevator as it approaches the main deck level.
There is a lower level near the base of the pylons - looking east
and west from almost the base of the east pylon