Peace Bridge: Traffic Sign Gantries
Fort Erie, ON Canada | 2019
Many major sign supports with large guide signs remain in place for at least 50 years. ODOT has had good experience with HDG structures that were installed in the middle of the 1960's and remain in good condition. As a result, HDG structures are used for many Traffic Structure support types to ensure that a minimum lifespan of 50 years is satisfied with little or no maintenance required.
Improved line of sight in a congested corridor with many options and restrictions for drivers!
There are many considerations when it comes to the design and choice of sign bridge structures. Longer spans and larger loads typically require truss style sign bridges. At this Sunnyside location, the span length installed is within the maximum span length allowed for a "monotube" style structure. Monotube sign bridges are often installed in congested corridors where there are a lot of other signs such as seen at this location. Monotube structures are also used to help reduce the amount of structure that will be in the way of the travelling public's view.
In settings such as this, feedback has consistently indicated that monotube structures are more aesthetically appealing than latticed truss structures. In addition, smaller signs and signals can be more difficult to see on a latticed horizontal member than on a single monotube member. Monotube structures have less manufacturing in regards to cutting members, fitting the members together, welding and inspection. The cost of monotube structures can be higher than a comparable truss sign bridge, but other factors usually justify the additional cost on a project specific basis. Part of this justification is lower maintenance than paint would require and longer life span due to the extended corrosion protection offered by HDG. Monotube sign structures require a smaller footprint than the older style truss type structure. Erection is quicker and creates less disturbance to traffic patterns as well.
The large diameter and radiused bend in the support column required this structure to be sourced from the mid-west. This same radiused large diameter pipe meant that the supporting column had to be progressively dipped for complete coverage. As opposed to the old style truss structure, transportation and material handling of these heavy radiused columns is a challenge from production to final erection at the job site. Structures such as this that are in highly visible locations would be less aesthetically pleasing if many repairs needed to be made to the structure prior to erection. Quality of the initial coating was of upmost importance.
Portland, OR United States
Coating Durability, Corrosion Performance, Ease of Specifying, Life-Cycle Cost, Prior HDG Experience
Radiused 30" shafts and 30" arms
Hogan Fab, Inc.
Clackamas Dept of Transportation and Development
Zinkpower USA - Portland
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