Sustainable Design

By Steven Foss
Feb. 6, 2015

Our environment – natural and built – is a complex network of components, creating unique and dynamic landscapes. Sustainable design focuses on maintaining and improving environments through a collaborative approach, considering how they fit within the greater ecosystem, and employing devices that are environmentally conscious and friendly. Sustainable design strategies typically include reducing carbon footprints; improving energy efficiency; and enhancing or protecting natural habitats while still providing economic, environmental, and social benefits.

Environmental benefits of sustainable design

The major goal of sustainable design is to preserve and improve our environment while reducing our carbon footprint and minimizing the use of natural resources. When sustainable design solutions are incorporated through project development, communities and the environment benefit through one or more of the following scenarios:

Protecting/conserving the ecosystem
Improved air and water quality
Reduced volumes of waste
Conserving natural resources

Social benefits of sustainable design

Implementation of sustainable design not only provides environmental benefits to our communities, but also improves our quality of life, health, and well-being. Improving the environment and integrating sustainable practices can have the following results on individuals and communities:

Improved active and passive spaces for social interaction and circulation
Improved emotional function
Reduced stress
Improved work effectiveness
Stronger sense of belonging and connection to the environment

Economic benefits of sustainable design

Incorporating sustainable design, through integrated design processes and innovative use of sustainable materials and equipment, can also generate economic benefits such as:

Reduced infrastructure needs
Lower annual costs for energy, water, and maintenance/repair
Reduced “heat island” effect
Improved ability to attract new employees/residents
Reduced time and cost for project permitting
Improved use of former sites (such as brownfields)
Reduced construction costs through reuse of construction materials
Increased property values

Summary

Sustainable design transforms conventional thinking about our landscape, infrastructure and buildings. It presents significant opportunities to improve our quality of life through environmental, social and economic benefits.

The following is a list of materials and tactics that can be incorporated into sustainable design practices:

Preserving existing tree cover and biodiversity
Vegetated swales/rain gardens
Dry and wet ponds
Green roofs
Underground storage and permeable pavement
Enhanced tree plantings (Silva Cells)
Infiltration devices
Alternative energy (wind, solar, biomass, geothermal, hydroelectric)
Conversion of mowed/maintained turf to low-maintenance native grasses
Stormwater capture and reuse for irrigation
Use of recycled construction materials

Forgotten cracks and sealing the joint

Sealing the joint

Over the years, both crack sealing and crack filling have proven to be very cost-effective tools in the preventive maintenance tool box. One area that has been overlooked when sealing streets and highways, however, has been the joints between two types of pavement – such as between an asphalt street and concrete curb or concrete pavement and the asphalt shoulder.

When a joint between two different pavements is left unsealed, water is unable to “jump the joint” and can end up saturating the underlying base materials and causing load-related failures. In areas where de-icing chemicals are used for snow removal operations, the flow of the residual brine can also cause the areas of infiltration to thaw earlier – increasing the likelihood of load-related damage during spring thaw.

Figure 1 – Asking Water to Jump Across a Joint

Where’s the proof that sealing these joints makes a difference in performance?

MnDOT recently did a study and published the Edge-Joint Sealing as a Preventive Maintenance Practice report, which showed that sealing the joint between concrete main line pavement and asphalt shoulders resulted in an 80% reduction in water infiltration. The assumption was that by keeping the base and sub-base drier, there would be better performance.

There are at least three methods of sealing the joints:

Rout and seal if the configuration of the joint will allow a router to be centered over it.

Clean and fill the joint if the concrete curbs have a pan that is too narrow to allow routing.

Apply a joint adhesive to the face of the concrete and pave the hot mix asphalt against it. Joint adhesive was developed specifically for application to cold paving joints to reduce water infiltration. It has a higher viscosity than a normal hot pour sealant, which allows a thicker layer to be applied to the face of the structure.

Figure 2 – Clean and Seal Joint

A best practices guide, called Recommended Performance Guidelines for Crack Treatment, can be found on the ISSA website.

Figure 3 – Two-year-old Joint Adhesive

When sealing cracks in pavement, don’t forget about the joints along the curb line or between the shoulder and pavements.

Reference:

Minnesota Department of Transportation. Edge-Joint Sealing as a Preventive Maintenance Practice. August 2003. (MN/RC 2003-26).

Using NDVI to Generate Impervious Surfaces for Large Areas

By Bryan Pittman
Feb. 6, 2015

Calculating the area or percentage of impervious surfaces for a given spatial extent helps determine curve numbers, runoff rates, and pollutant loadings. Overlaying an impervious surface layer with drainage areas for a city can determine impervious percentage per drainage catchment. The issue is getting an impervious surface for a large enough area, for example a city or a Watershed Management Organization (WMO). Digitizing of an aerial can create impervious surfaces for small areas but is too time consuming on a large scale.

Fortunately, with the current availability of high-resolution Color-Infrared (CIR) aerial photography, there is a workaround that is far less time consuming. Since the reflectance of vegetation peaks in the near infrared, vegetation yields high returns on CIR photography. This can be used to generate a Normalized Difference Vegetation Index (NDVI). The NDVI is a ratio from the returns of near infrared and visible light, telling us how “alive” something is. A high NDVI ratio signifies healthy, growing, green vegetation, where a low NDVI ratio signifies something not living, say pavement or rooftops.

The typical NDVI value ranges from -1.0 to +1.0 (GIS software calculates a value from 0 to 200). In that range, there will be a cut-off point that separates vegetation from non-vegetation. The value is typically just above 0.0, but varies based on the CIR aerial photography being used. Classifying the NDVI surface into two groups from that cut-off point gives a result that shows the area of vegetation and non-vegetation. Since there is a very high correlation between areas of non-vegetation and impervious surfaces, this result shows what is impervious and what is pervious.

This method yields results that are about 90 percent accurate. First, the assumption is made that vegetation equals pervious surfaces, which is not always the case. A large area of open dirt is a good example. It is still pervious but shows up as impervious because it is not vegetation. Another issue is shadows cast by trees, houses, and other structures. Since shadows are blocking out the light return (both visible and near infrared), any shadow is interpreted as non-living and thus impervious, even though it may be a pervious surface.

Even with these minor disadvantages, the time saved is enormous. Instead of taking weeks to digitize all the impervious area within a city, this analysis can be completed in under an hour. It is necessary to perform quality control on the data and clean up any of the issues described above by reclassifying something as pervious to impervious or vice versa.

The Alphabet Soup of Minnesota Environmental Review: EAWs, AUARs and EISs

by Andi Moffatt
Feb. 6, 2015

Acronyms

AUAR: Alternative Urban Areawide Review
EAW: Environmental Assessment Worksheet
EIS: Environmental Impact Statement
EQB: Environmental Quality Board
MEPA: Minnesota Environmental Policy Act
NEPA: National Environmental Policy Act
RGU: Responsible Government Unit

Introduction

The Minnesota Environmental Policy Act (MEPA) and Minnesota Rules 4410 require some projects to undergo environmental review prior to obtaining permits or approvals. The purpose of this review process is to avoid and minimize damage to environmental resources (Minnesota Rules 4410.0300). The Environmental Quality Board (EQB) promulgates rules and provides guidance to the state’s environmental review program. This article provides information about the Minnesota environmental review process, discusses some triggers for environmental review, and discusses general timelines for the process.

Background

The MEPA was enacted in 1973. It was modeled after the federal National Environmental Policy Act (NEPA), but written to specifically address other projects the state, public, and agencies deemed to need environmental review.

Three documents are the basis for Minnesota’s environmental review program:

Environmental Assessment Worksheet (EAW)
Environmental Impact Statement (EIS)
Alternative Urban Areawide Review (AUAR)

All three documents generally analyze similar topics for a given project, including stormwater management; wetland, habitat and fisheries; water and wastewater; traffic; air; noise; cultural resources; pollutant sources; and impact to infrastructure and the environment. The main difference between the documents is the extent and level of analysis needed.

The EAW is the heart of the state’s environmental review program. The purpose of the EAW is to determine if an EIS is needed. The EAW is intended to be a basic document, while an EIS goes into much more detailed analysis and investigation and is required if a project meets a mandatory EIS threshold or if the EAW cannot adequately gauge the possible environmental impacts of a project.

An AUAR can be thought of as a hybrid between an EAW and an EIS. While an EAW and EIS are used for specific projects (e.g., a big-box retailer proposing to develop within a city), an AUAR is used to analyze different development scenarios where a specific development is not known. Cities can use AUARs to analyze general development of a section of their city, understand possible impacts of the development, and identify specific mitigation measures. An AUAR can also be used for certain specific development plans that may trigger an EIS as an alternative to the EAW; however, there are additional review steps in these unique cases. Additionally, some types of development, such as heavy industrial development, cannot use the AUAR process.

The table below generally summarizes when to use each document.

EAW	EIS	AUAR
Project with a specific development plan Required by Minnesota Rules 4410 If petition for review is granted RGU discretion	Project with a specific development plan Required by Minnesota Rules 4410 EAW determines it is necessary Projects with significant impact	Projects with undefined development plan Large tract of land anticipated to develop Can be used in some cases if EAW or EIS is required (check rules beforehand)

Environmental review triggers

There are many different triggers for a mandatory EAW or EIS, which depend on factors such as the location of a project, the type of project, and the city where the project is located. Common EAWs or AUARs include reviews for new residential development, construction of light industrial or commercial areas, new sanitary sewers of a specific capacity, some road projects, and projects that have large impacts to wetlands or water bodies. A full listing of the environmental review triggers can be found here.

The public can also petition to have an EAW completed for a project. In this process, a petition must be submitted to the EQB with at least 100 signatures. The EQB reviews the petition for completeness and submits it to the RGU for technical review and a final determination.

Timeline

Timelines will always depend on the specifics of an individual project or review. A general rule of thumb, however, for the time it takes to develop these documents is as follows:

EAW: 3-5 months
EIS: 1-3 years
AUAR: 1 year

Who completes the document?

The rules specify the RGU for each type of project. It is often the land use authority (a city or county) but could also be the Minnesota Pollution Control Agency or another agency. The project proposer is required to supply certain information to the RGU to complete the document. The RGU is responsible for making sure it is accurate and complete. We have seen this process work in one of two ways: sometimes, the RGU prepares the document with information provided from the project proposer; in other instances, the project proposer prepares the document and then the RGU reviews and finalizes it. Both ways are acceptable.

Review process

Once a document is complete, it is submitted for a 30-day public comment period and is sent to the required review agencies. After the comment period, responses will be prepared.

For an EAW, a Findings and Conclusions document is prepared for the RGU decision-making authority, such as a City Council, which is tasked with reviewing the document and preparing a Record of Decision on the Need for an EIS.

For an EIS or AUAR, a final document is prepared that includes revisions based on the comments received prior to going to the RGU decision-making authority.

What does this mean for you?

Check the required triggers for an environmental review early in the project proposal process. A project’s timeline may be impacted by required reviews. Additionally, there is a prohibition on governmental approvals and construction until the environmental review process is completed.

Complete information can be found at the Minnesota Environmental Quality Board website.

Tracking Santa: An ArcGIS Online case

By John Mackiewicz
February 6, 2015

ArcGIS Online connects maps, apps, data and people so you can make smarter, faster decisions. It gives everyone – both inside and outside organizations – the ability to discover, use, make and share maps from any device at any time. At its core, ArcGIS Online is a hosted cloud software as a service (SaaS) platform. Everything you need to create your own web maps and apps is available on ArcGIS Online. You can create maps from Microsoft Excel or upload your data from ArcMap to share your map and collect data in the field on your tablet or phone.

ArcGIS Online supports many users collecting data in the field at one time. This presents a problem for large workforces, as you may need to track where your collectors go when working in the field. Using Esri’s Collector for ArcGIS app, you can have it periodically report the location of data collectors back to a tracking layer on ArcGIS Online by publishing a tracking layer on ArcGIS Online and adding it to an Web Map with tracking enabled. When this Web Map is accessed within the collector app, the collector app sends its GPS location back to the tracking layer hosted on ArcGIS Online at a predefined interval.

At WSB, we view ArcGIS Online as a technology that:

Can quickly be deployed for multiple uses
Is flexible enough to handle diverse workflows without requiring any programming
Has untapped potential for public outreach

Below is one of our favorite examples of how we used ArcGIS Online to help a client deliver immediate value to both the organization and the public.

Tracking Santa

For more than 25 years, firefighters in the City of St. Anthony, Minnesota, have helped Santa by collecting gifts for those in need. Santa rides in fire trucks throughout the city collecting gift donations from residents. In 2014, the city wanted to allow residents to track Santa’s location along his route.

The City of St. Anthony decided to utilize ArcGIS Online to track Santa, thanks to all the app’s capabilities.

Here’s how we did it:

A tracking layer was published on ArcGIS Online.
The tracking layer was added to a Web Map configured with the city’s custom Esri base maps with tracking enabled.
The city deployed an iPad with the Esri Collector for ArcGIS app to ride along with Santa with the Web Map open on the fire truck.
A custom web app was built using our DataLink platform to show Santa’s most recent location.

As the fire truck drove along its route, the collector app was configured to report the truck’s location every 30 seconds back to ArcGIS Online. Residents used DataLink to view Santa’s current location in relation to their house so they knew when Santa was arriving.

Tracking Santa’s location is certainly a unique use of ArcGIS Online, but it shows how extensible the ArcGIS Online platform is. With just a few clicks, you can begin to track real-time locations of users who are using the collector app.

Planned unit developments: Easing zoning ordinances in exchange for creative development

By Addison Lewis
October 21, 2016

What is a Planning Unit Development (PUD)?

A Planned Unit Development (PUD) is a zoning designation used to ease the strict application of a zoning ordinance in exchange for creativity in development. A PUD is often used to provide deviations from standards such as setbacks, height, density, uses, and other regulations. A PUD is used when planning for larger areas (one acre or more), planning for multiple contiguous sites, or accommodating multiple buildings on one site. The area should be under unified ownership at the time of a land use application for a PUD. In exchange for deviations from the zoning requirements, benefits such as additional greenspace, pedestrian or transit amenities, enhanced energy efficiency or stormwater management, affordable housing, mixed use, or enhanced architectural features are usually provided by the developer to achieve a higher quality development that might not otherwise occur.

When to use a PUD

A PUD is used to implement development goals identified in a community’s comprehensive plan. PUD process is not just an alternative to variances – it should be considered for unique development projects where the public benefit or development goal is clearly understood, and when the project would not otherwise be permitted through strict application of the zoning ordinance.

What to consider when developing a PUD

When developing a PUD ordinance, be sure to identify amenities or conditions that will help achieve the goals and objectives of the community’s comprehensive plan. A PUD ordinance should only be used if these amenities or conditions are offered by the developer. You may want to specifically list in the ordinance which specific zoning standards were deviated from.

A PUD designation is a similar process to rezoning. Think of each PUD as a customized zoning district that specifically identifies the location of buildings, uses, architectural design, etc. A PUD is a great tool for encouraging creativity and providing flexibility from the zoning ordinance, but once it is adopted any future change could require an amendment, depending on whether it is a major or minor change. A minor change can be approved administratively, while a major change would need to follow the same process as a rezoning. The community’s ordinance should identify which changes are considered minor or major.

Wildlife Passage Bench

By Roxy Franta
February 1, 2016

A passage bench, or “critter crossing,” is a gravel walking path incorporated into the riprap along a bridge abutment to allow wildlife to pass under bridges uninterrupted. Many species of wildlife travel along the natural shoreline of streams, but modern infrastructure often breaks the continuity of the shoreline. Traditional riprap is not passable by many animals, forcing them to leave the shoreline and cross at busy bridge approaches. Wildlife on roadways presents safety hazards to both the animal and drivers, but including a passage bench into bridge design is an easy solution to this common problem in Minnesota.

(photo credit: Minnesota Department of Natural Resources)

Why include a passage bench?

The idea of a passage bench was developed by the Minnesota Department of Natural Resources (DNR), the U.S. Fish and Wildlife Service (USFWS), and the Minnesota Department of Transportation (MnDOT) in 2005. Continued observations prove this feature to be successful, providing benefits such as:

Movement of animals under the bridge, increasing road safety of bridge approaches
Safe footing for bridge inspectors and fishers
Access for maintenance
Flexibility in design for cross-section of normal channel and flood profile
Riprap design change from aggregate base to geotextile base
No extra cost or time to install
Wildlife conservation by minimizing deaths from collision

Designing a bench

In 2011, the passage bench became part of the MnDOT Standard Plan Set for use on all bridges. Specifications for passage bench design can also be found in the “Best Practices for meeting DNR General Permit 2004-0001, March 2006” guidelines.

The passage bench is a level trail from one side of the bridge to the other. It should be constructed of any size aggregate that is “walkable,” to allow wildlife proper footing as they pass under the bridge. The bench should be placed at or slightly above the adjacent bank elevation to create a continuous path that mimics the natural contours of the streambank and should be tied into the groundline outside the bridge area. A typical game trail width of three feet has proven to be successful for animal movement.

Common mistakes

The passage bench is a relatively simple addition to bridge construction, but there are some common mistakes to avoid during installation.

Having the riprap block the path. It’s important to incorporate the passage bench into both the grading and bridge plans to ensure it is completed and continuous across the entire area. Drainage outfalls and associated riprap along the abutment should be placed below the bench.
Too high or too low. The height of the passage bench often doesn’t match the natural streambank. A good indicator for the bench elevation is to place it at or just above the vegetation line.
Lack of guidance for wildlife. Though not a requirement in Minnesota, the right-of-way (ROW) fence should be used to guide wildlife to the passage bench. ROW fencing is often extended parallel to the roadway until it reaches the stream at the bridge. Instead, the fence should be turned up at the abutment and installed tight against the bridge corner. If it is a divided highway, a median fence should be installed as well.
Too skinny. MnDOT specifications suggest a minimum bench width of three feet. Benches that are too narrow are subject to longitudinal scouring during flood events and are not used as often by wildlife.
Construction phasing. Contractors often wait to install the passage bench until all other work is complete, but this makes it impossible to mechanically install it once the bridge beams are set in place. Installation should occur with riprap installation and should be a planned part of construction phasing.

Success

MnDOT funded a study of the passage bench and collected data on wildlife movement and utilization in 2009. They concluded that a wide variety of species use the passage including black bear, red fox, gray fox, bobcat, whitetail deer, and even humans.

Roadway networks have caused fragmentation in the natural environment, but as a construction planner, design engineer, or contractor, you can help minimize this conflict between wildlife and highway operation with the inclusion of a passage bench.

Resources:

What Makes a Wetland a Wetland?

By Joe Handtmann
June 10, 2015

A wetland is a flooded area of land with a distinct ecosystem based on hydrology, hydric soils, and vegetation adapted for life in water-saturated soils. Wetlands are heavily protected by federal, state, and local policies due to their environmental benefits and the historical filling and dredging that removed more than 50 percent of them across the country. Wetland types vary based on their location. Mangroves are found along the shores of salty waterbodies while peat bogs are found in cool climates, where slow decomposition facilitates the accumulation of peat over long periods of time. Common wetlands in Minnesota include wet meadows, shallow and deep marshes, scrub-shrub wetlands, and bogs.

Requirements and delineation
To be considered a wetland, the site must have the presence of water, soils indicative of frequent and prolonged flooding, and vegetation suited to handle flooding or saturated soils. Determination of wetland boundaries must be done by a certified wetland delineator based on the Army Corps of Engineers Wetland Delineation Manual and appropriate regional supplements. Delineations are subdivided into levels. Level one means onsite inspection is unnecessary; level two means onsite inspection is necessary; and level three, which is a combination of levels one and two.

Hydrology
Identifying hydrology, or presence of water, can be as simple as noticing the sustained presence of water in boreholes or manually measuring surface water, or as difficult as requiring the use of continued monitoring wells and piezometers. Areas with a surface water depth of more than 6.6 feet are considered deepwater aquatic habitats and not wetlands.

Hydric soils
Soils that are saturated for a long period of time display common visual patterns identifiable in a soil profile. Soils developed in anaerobic conditions show unique colors and physical characteristics that are indicative of hydric soils. When water continuously saturates the ground, organic soils are likely to occur. Organic soils are referred to as peats or mucks and require more than 50 percent of the upper 32 inches of soil to be composed of organic material. Hydric mineral soils form under a range of saturated conditions, from permanently saturated to seasonally saturated. Indicators for hydric soils can be found in the Field Indicators of Hydric Soils in the United States guide, published by the USDA.

Hydrophytic vegetation
Wetland vegetation is classified by its ability to survive in saturated soil conditions. These classifications range from OBL (obligate wetland plants that usually occur in wetlands), to FAC (facultative plants that occur in wetlands and non-wetlands equally), to UPL (obligate upland plants that are rarely found in wetlands). When OBL, FACW, and FAC species make up the vegetative species at a site, then the site is considered to have hydrophytic vegetation.

Classification
Two main systems are used to classify wetlands in Minnesota – the Circular 39 and the Cowardin systems. Both systems are commonly used when writing permit applications or describing or writing about wetlands. A noteworthy exception is the case of the National Wetlands Inventory, for which the U.S. Fish and Wildlife Service exclusively used the Cowardin system.

Circular 39
The Circular 39 system was developed by the U.S. Fish and Wildlife Service in 1956, and divides wetlands into eight different types based on water depth and variety of vegetation.

Type 1: Seasonally Flooded Basin/Floodplain Forest: Soils are flooded during variable seasonal periods. Often found in upland depressions, these wetlands are well-drained during the rest of the year. Vegetation can be quite variable.
Type 2: Wet Meadow, Fresh Wet Meadow, Wet to Wet-Mesic Prairie, Sedge Meadow, and Calcareous Fen: Soils in these wetlands are usually without standing water, but saturated close to the surface. Vegetation includes sedges, grasses, rushes, and broad-leaved plants. These wetlands are notes for their wildlife habitat capabilities.
Type 3: Shallow Marsh: Shallow marshes are covered with more than six inches of water throughout the year. Typical vegetation includes grasses, cattails and bulrushes.
Type 4 – Deep Marsh: Similar to shallow marshes, deep marshes are covered in water from six inches to three feet deep. Cattails, reeds and lilypads are common.
Type 5: Shallow Open Water: Water is present, but less than six feet deep and fringed with emergent vegetation. This type of wetland is often used for fishing, canoeing and hunting.
Type 6: Shrub Swamp; Shrub Carr, Alder Thicket: Soils are heavily saturated and may be covered in up to six inches of water. Dogwoods, willows and alders are all common species.
Type 7: Wooded Swamps; Hardwood Swamp, Coniferous Swamp: Typical trees in wooded swamps include tamaracks, white cedar, arborvitae, black spruce, balsam, red maple, and black ash. The prevalence of trees helps control water flow during flood events. Soils are saturated up to a few inches of the surface and may be covered by up to a foot of water.
Type 8: Bogs; Coniferous Bogs, Open Bogs: Organic soils are prevalent in bogs, with continually waterlogged soils and a spongy covering of mosses. Shrubs, tamaracks, mosses, and black spruce are all common species.

Cowardin
The Cowardin system was developed in 1979 for the U.S. Fish and Wildlife Service to classify wetlands and deepwater habitats. This system was used in the National Wetlands Inventory to identify wetlands. Two major wetland types, coastal and inland, are identified. All Minnesota wetlands are defined as inland (palustrine), which is then subdivided based on vegetation classes and bed material.

Envision: The Age of Sustainable Infrastructure is Here

By Brandon Movall
Aug 1, 2016

With the state of America’s infrastructure declining due to climate change and limited funding, today’s engineers and scientists must adopt creative and sustainable solutions. In 2011, the American Society of Civil Engineers (ASCE), the American Council of Engineering Companies (ACEC), and the American Public Works Association (APWA) came together to revolutionize the way engineers plan, design and build. The result was Envision, a holistic rating system for sustainable infrastructure.

Envision is a rating system to help project teams incorporate higher levels of sustainability at each step of a project, from assessing costs and benefits over the project lifecycle to evaluating environmental benefits and using outcome-based objectives. Envision considers social, environmental, and economic factors of projects (a process called the Triple Bottom Line), rather than only focusing on economic factors. Envision uses a scorecard of 60 credits divided into five categories that reflect all aspects of the Triple Bottom Line:

Quality of Life
Leadership
Resource Allocation
Natural World
Climate and Risk

By tallying the credits achieved throughout the project lifecycle, Envision is able to effectively rate proposed infrastructure options in a way that is easy to communicate to clients, consultants and owners.

While there are many sustainability rating systems out there, there are a few things that make Envision the best option:

Envision rates all types of civil infrastructure, such as transportation, water, energy, information, and landscape infrastructure.
Envision covers the entire life cycle of a project, from the first meeting of the project team to post-construction maintenance.
Envision is free to use. Anyone can sign up for an Envision account and have access to the guidance manual and scorecard. The only costs involved are if a project is registering for awards through Envision, or if you want to get special training and become an Envision Sustainability Professional (ENV SP). These are optional and are not necessary to use the Envision system on a project.

In addition to individual users, many companies and public agencies across the United States have implemented Envision into their planning, design and construction processes. Benefits to a company or agency include discounted ENV SP certification rates, discounted project award registration rates, exclusive content from the founding organizations, and more. As part of our commitment to bettering ourselves, our clients, and our world, WSB is proud to be recently certified as an Envision qualified company.

To change the world, we must change our practices. Envision is one large step toward planning, designing and building a sustainable future. For more information about Envision in general, visit www.sustainableinfrastructure.org. For more information about Envision at WSB, please contact Katy Thompson, Brandon Movall, Stephanie Hatten, or Ann Wallenmeyer.

References:

“2013 Report Card for America’s Infrastructure.” 2013 Report Card for Americas Infrastructure. ASCE, n.d. Web. 28 July 2016.

“Envision.” Institute For Sustainable Infrastructure. N.p., n.d. Web. 28 July 2016.

Bridges – An Overview

by WSB Municipal Engineering
Dec. 22, 2016

What legal responsibilities do bridge owners have?

Any municipality that owns a bridge in Minnesota must appoint a bridge program administrator. This administrator needs to be a professional engineer with a bridge background, as they are responsible for ensuring their bridges are inspected, load rated, and load posted (if required) according to state and federal law.

What does a bridge safety inspection involve?

A bridge safety inspection is an evaluation of the physical condition of a bridge. The inspection involves a visual and hands-on evaluation of all bridge components. The inspector looks for issues such as corrosion, deterioration, settlement, damage, or scour, and the results are detailed in a report based on each component. Following a bridge safety inspection, the overall condition of the bridge is compiled in an online database. Bridges are required by law to be inspected either annually or biannually, depending on the bridge type and condition. Special inspections such as an underwater inspection may also be necessary for bridges with components that are not visible during low water conditions.

How does a bridge owner know when it is time to replace a bridge?

The answer to this question varies based on the volume and type of traffic over the bridge. Bridges should always be replaced before the safety of the traveling public is at risk. Every bridge is assigned a sufficiency rating score, which varies from 0-100 and factors in the condition of the bridge, traffic volume importance of the route, and load carrying capacity. A bridge’s sufficiency rating is used to determine when it should be replaced and when it qualifies for funding. Bridges are also replaced when they are no longer able to meet traffic needs. Bridge owners can significantly extend the life of bridges by performing routine maintenance such as painting, cleaning, and crack sealing.

What is a bridge load rating?

A bridge load rating is a calculation that determines the safe load carrying capacity of a bridge. Bridge load ratings are based on the original capacity of the bridge while factoring in any deterioration or changes to the bridge’s condition that have occurred over time. A bridge load rating calculation is required when the bridge is first constructed and whenever the condition or configuration of the bridge has changed. The results determine if a bridge should be load posted and if it is safe for special permit vehicles to cross the bridge.

Glossary

Load Rating: A calculation to determine the safe load carrying capacity of a bridge.
Load Posting: Restricting the weight of vehicles that cross a bridge in order to prevent overloading.
Sufficiency Rating Score: A numerical value on a scale of 0-100 that considers a bridge condition, traffic volume importance, and load carrying capacity.

Co-authored by Jay Kennedy and Diane Hankee.

The text of this article contains general information and is not intended as a substitute for specific recommendations. Your professional staff is more familiar with your community and can provide specific recommendations. Guidelines and regulations change and may be different from when this article was published.