It is common sense that the better you take care of something the longer it will last. The same is true with pedestrian bridges, but rarely do parks, municipalities, golf courses or private owners have their pedestrian bridges inspected. This drastically shortens the life of many pedestrian bridges and they end up needing to be replaced. In most cases, these pedestrian bridges would have lasted much longer if a routine inspection had been performed, which usually amounts to simple and inexpensive repairs.
What specifically is inspected on a pedestrian bridge?
Inspection of pedestrian bridges involves inspecting the four key elements of a pedestrian bridge:
Foundations
Most pedestrian bridges are developed from concrete and connect the ground to the structural supports. There are several common issues that foundations can face over time, including the following:
- Concrete Cracking: Concrete can start to crack from the settlement or thermal strain over time. When these cracks are small they are easy and inexpensive to fix.
- Settlement: Over time concrete foundations can settle into the ground causing the bridge elevation to lower. When this settlement is minor the foundation can typically be jacked up before structural damage is done to the bridge or approaches to the bridge.
- Washout: Washout is when the erosion from water flow removes the dirt around the bridge foundation. This can cause the bridge foundation to start to lean or settle. When this is caught early it’s easily stopped by the addition of larger diameter rocks that are not moved by the waterflow.
Structural Supports
The structural supports are the materials that span the load between the foundations. For most pedestrian bridges these are made of wood or steel members. There are several common issues that structural supports can face over time.
- Corrosion: Corrosion can take many forms depending on whether the beams are wood or steel. For painted or galvanized steel supports, a simple touch up to damaged paint/galvanization can greatly extend the life of the bridge. Wood beams coated with stain or other protective treatment can greatly increase the life of the bridge.
- Structural Damage: Structural damage to the primary structural supports is a major concern for pedestrian bridges and should be thoroughly inspected at each inspection interval. In a lot of cases these structural concerns start as minor physical damage to the supports and they can be repaired easily if it is caught before this damage expands over time.
Deck System
The deck system is the material that users walk on; usually the material is fabricated from wood, fiberglass or concrete. There are several common issues that deck systems can face over time, including the following:
- Concrete: Surface cracks and spalling are common issues faced by concrete surfaces. These can be prevented by sealing the concrete every few years and fixing cracks when they first start to form.
- Wood Decks: With treated lumber decking the boards can begin to rot and/or warp over time. Replacing these deck boards as they get to their usable life keeps the bridge in a safe condition for the users and eliminates trip hazards.
- Fiberglass Decks: The advantage of fiberglass decks is their incredibly long lifespan, but they typically have a non-skid coating on them that can accelerate UV damage if they aren’t maintained.
Railing Systems
The railing systems that are typically used on pedestrian bridges are wood, steel and aluminum. There are several common issues that railing systems can face over time depending on the materials of construction, including the following:
- Wood Railing: With treated lumber railing the boards can begin to rot and/or warp over time. Replacing these boards as they get to their usable life keeps the bridge in good safe condition for the users.
- Steel Railings: Painted steel railings are susceptible to corrosion from chipped or damaged paint. The paint should be inspected and repaired to prevent this corrosion from penetrating into the structural capability of the railing system. If this is caught early on it is very easy to prevent.
- Aluminum Railings: Aluminum railings are great at long term corrosion resistance but are highly susceptible to damage from impacts or falling trees. Since most aluminum railings are modular, small sections can be replaced when these issues are found through inspection.
What does pedestrian bridge inspection cost?
Pedestrian bridge inspection for parks, municipalities, golf courses and private owners are typically about $750 or less per bridge for most pedestrian bridges that are less than 60ft long. As the bridge gets larger and more complex the cost can increase.
Who should inspect my pedestrian bridge?
A licensed professional engineer that is familiar with pedestrian bridges should inspect your pedestrian bridge and provide a simple report that highlights the bridge deficiencies and the recommended repairs that should be completed. This initial inspection should also create the basis for the future inspection schedule. For bridges that are in great shape there is typically no need to inspect the bridges more than once every five years. As the bridge conditions get worse the inspection frequency should increase.
At Axcess, LLC, we want you to be aware of all the options for design, inspection, and installation of pedestrian bridges so you can make the best decision based on your needs. Please get in touch to talk about your bridge!
