Re: Florida's Turnpike designs generic ORT gantry
- From: "Mike Tantillo" <mjtantillo@xxxxxxxxx>
- Date: 2 Feb 2006 10:27:49 -0800
Larry Gross wrote:
exerpts:
Florida Turnpike Enterprise (FTE) has a standard open road tolling
(ORT) gantry design to provide more efficient maintenance of overhead
equipment and also to present a visual theme to tollroad users.
The first of the new gantries will be erected on the final southern
segment of the FL429 Western Expressway tollroad under construction
southwest of the Disney theme parks near Orlando. That is due to open 7
Dec 2006.
Another 25 of the generic ORT gantries are planned for other locations
on the FTE tollroad system.
Key requirement for the gantry was to allow all work on overhead toll
equipment to be done from above, so that a lane will never have to be
closed to traffic for a bucket truck.
Structure
The gantry has a span of 24m (80ft) allowing it to bridge over up to
four travel lanes plus full shoulders each side.
The structure relies on a parallel pair of 26 inch (0.66m) diameter
steel tubes 8 foot (2.4m) apart. The walkway in between acts as a
lateral bracing member. It has a lower level of removable grating with
0.3m (12in) to house cables and RF gear such as readers.
Rectangular sections rise from each large tube at a 12 degree angle
outward to support screening panels that form a striking fascia for
motorists. The fascia is topped by a pair of 8 inch (0.2m) tubes,
slightly arched for style.
Lighting is designed to lighlight the arched top line with just a drift
of light for the remainder of the structure. The SunPass logo is the
only signage planned to give it a clean appearance.
Screening panels
The screening panels that give mass and color to the structure are just
4mm thick (0.16 inch) - of an aluminum composite material, It consists
of a pair of aluminum sheets bonded onto a thermoplastic core - a
system widely used in commercial buildings for cladding, soffits, gas
station canopies, and fascia bands.
The cleverness of the design lies in way the screening panels can be
opened inwards like doors and the equipment arms rotated upward into
the walkway so that cameras, antennas and other gear can be installed,
replaced, serviced, or adjusted up there inside the walkway.
The swingdown gantry arms are designed to support RF antennas for
reading transponders, video gear including cameras and their
illuminators.
The arms have to adjustable in angle and elevation. They must be
positioned at 5.5m (18ft) to 5.6m (18.5ft) above the pavement, but the
distance between the bottom of the gantry and the pavement - a minimum
of 6.1m (20ft) - will vary depending on the side slope or
super-evelation of the roadway surface below.
Antennas and video gear
The FTE design requires an antenna and three cameras to cover each
lane. One of the cameras is for frontal pictures of tractor trailers.
All the vehicle detection and tracking is planned to be done with
pavement loops.
Jeakle says nothing in the requirements provides space for any
overhead detection, tracking or profiling equipment - laser or video.
Artists used to draw ORT gantries as elegantly light structures, but
they would sway in high wind. To get sharp pictures the video equipment
needs a rock solid platform.
Inside at least one of the two columns is a man ladder plus space for
mounting up to 40 cables needed to provide power and make connections
with the video and RF gear.
The designers looked at an internal circular stairway but it would have
made the column very fat and ungainly in appearance. A circular stair
would be over 2m (6.5ft) diameter and even then there would be problems
accommodating cables.
The current design has an inconspicuous equipment hoist on the outside
that runs in a pair of slots. RF modules, antennas, lights, cameras,
tools, and cable will go up the outside hoist.
Next project is a generic ramp gantry
The logical follow-on project is a ramp gantry design that matches the
look and functionality of the mainlanes one. Jeakle says there is
nothing on that yet.
They look like they aleady have a ramp gantry design of sorts. The
Sun-Pass Only exit from the Turnpike south to SR 528 west has a gantry
over it that looks similar to the mainline OTR gantry, but with a
slightly different design. I liked the way it looked when I saw it.
http://www.tollroadsnews.com/cgi-bin/a.cgi/MW.syJOoEdqcEIJ61nsxIA
.
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