No two bridge projects are ever alike. Even a small bridge can present unforeseen obstacles that can create added costs. But by answering a few questions at the beginning of a bridge project, you can help ensure the project gets off to the best possible start, ultimately preventing delays, boosting public satisfaction, and increasing the lifespan of the bridge.
- Do We Really Need Soil Information?
The answer is “yes” if you want the most economical design and a design that is most compatible with the actual soil conditions at the site. Many people may think they are saving money by skipping a geotechnical investigation, but it forces the structural engineers to guess about the load capacity of the soils and other soil properties that are central to the design. Without a geotechnical investigation, the structural engineer is forced to be conservative in the design, likely driving up the cost of the bridge. The added costs due to a conservative design are likely to be more than the cost of the geotechnical investigation.
- Does Traffic Need to Be Maintained Throughout the Project?
Before beginning a project, municipal or county officials will need to decide how important it is to maintain traffic during construction. While maintaining traffic is often more costly and can lengthen construction time, depending on the route, a detour may cause undue inconvenience to the public.
- Will the Roadway and Stream Alignment Cause Any Special Design Considerations?
The alignment of the roadway will likely play a big part in what type of bridge is best suited to the site. For instance, if a medium-span bridge is needed and it is on a horizontal curve, a cast-in-place concrete slab will likely be the best deck type because of the ability to form the edges of the deck. Stream alignment relative to the bridge foundations should be closely evaluated because it can have a major effect on scour potential. Poor stream alignment causes scour to occur more easily, adding maintenance costs and likely reducing the lifespan of the bridge.
- Is the Project in A FEMA Special Flood Hazard Zone?
If a bridge is in a flood zone, there are special design considerations. For instance, a bridge that crosses a stream in a flood zone has to be high enough and long enough to avoid causing an increase in the flood elevation. This often results in a bridge that is larger than what would otherwise be required for non-flood zone stream crossings. Coordination with the local floodplain administrator is also required when the site is in a flood zone.
- Where Are the Utilities?
Design should not begin without accurately identifying the precise location of utilities and including that information in the survey of existing conditions. Accidentally hitting a utility during construction is extremely dangerous and will cause costly delays. The design of the bridge should be such that as few utilities as possible will have to be moved to accommodate the construction.
- Will Environmental Permits Be Needed? What About an Environmental Assessment?
The design of the bridge can drive whether an individual permit (a long, drawn-out process) is needed, or if the design can qualify under a nationwide permit. But other issues, such as if there are wetlands in the area, will also affect the permitting process. Nearly every bridge project should begin with an environmental review to identify those potential issues.
Ultimately the right project manager can help you make choices that are both cost-effective and will have a positive long-term impact on your community.
At the Kleingers Group, our team of structural engineers and bridge inspectors are focused on innovative ideas to build and restore bridges, cost-effectively and quickly. Our licensed structural engineers work closely with our transportation engineers to ensure coordination is seamless and meets your project’s needs.
Contact Mike Brunner at email@example.com to learn more about how Kleingers can help with your next bridge project.