Visualizing Pavement Distress–The Complete Story of Pavement Inspection

Pavement management incorporates data collected utilizing various methods to gain a complete view of how the pavement is performing through its life-cycle.  One of the most common practices in pavement inspection is imaging utilizing high-resolution cameras mounted on vehicles outfitted with precision GPS and inertial navigation.  This imaging, when combined with laser profiling, constitutes a typical pavement inspection setup utilized by many DOTs as well as Local government agencies.

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Pavement Inspections tend to follow a process that in many cases is proprietary and “black box” in nature.  This makes it hard for the purchasing agency to see how their roads were inspected and how the resulting pavement condition scores were generated.  Our team of Engineers and GIS professionals have worked hard to develop a process to remove the “black box” related pavement inspection and to make it easy and simple to trace inspection results back to their originating distresses from the field.

First, our entire process is geospatial in nature from the get-go.  Our van’s location is tracked in six-dimensions in real-time and this information is used to calculate the exact location of pavement cracks in the resulting images.  Next, the pavement images are geospatially referenced in 3-d and 1mm-pixel resolution, making it easy to extract low-severity cracks in a true 3-d environment.  This process then allows us to create GIS vectors (points, lines and polygons) of each distress for each pavement image and deliver them to our clients as part of the pavement inspection deliverables.

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This is a crucial piece to the pavement inspection “story” because it shows the purchasing agency exactly what distresses were identified and measured when creating the pavement condition scores for a section of road.  Being able to see these distresses on a map helps to complete the story by providing the ability for a rigorous QA/QC process utilizing some simple GIS tools.

Each Section of road can be colored by the condition score and its range of values.  This tells one component of its story.  The underlying distress information tells the rest of the story related to “How” a section of road was scored and assigned its inspection score.  By having this information at their fingertips, pavement inspection personnel have a GIS-centric and user-friendly tool that allows them to QA/QC pavement inspection data efficiently.

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Asset management strategies–which is right for me?

We get a lot of questions about developing the right strategy as it relates to assets that are managed by different agencies.  These questions are typically focused on “How” to manage assets, which typically comes after the agency decides “Why” to manage assets.

Here are some typical questions:

  1. When is the best time to manage my asset in its life-cycle?
  2. When do I rehabilitate my asset?
  3. What do I do to the asset?
  4. When do I replace my asset?
  5. Can I just let it runs its course and when it fails, replace it?
  6. Should I invest time and money in an asset early in its life-cycle or wait until it is in poor condition to fix it?

We always recommend starting this process by understanding a few things about the asset.

1.  Financial Considerations – How much does an asset cost to install and Maintain?  Is it capitalized or not?   In most cases, the cost of an asset has a large impact on how it is managed.  This is not the only consideration, but we can use it as a starting point.

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2.  Risk Considerations – What are the consequences to the agency if this asset fails?  Will someone get hurt?  Will it cause an accident?  These are closely tied to other financial considerations such as tort liability.

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3.  Life-Cycle Considerations – How does the asset typically deteriorate?  Is it straight-line deterioration or more of a polynomial-type of a curve?  This information helps determine what to do to an asset and when to do it (less cost when starting earlier in the process).  Programmatic treatments or inspection-driven treatments are common approaches to managing assets with this approach.

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Once an agency has a solid understanding of the Financial, Risk and Life-Cycle considerations related to an asset, they can begin to develop a management strategy specifically for the asset type to be managed.  Since every asset can be managed differently, we will focus on a couple of assets and their management strategy.

Pavement

  1. Financial – Capitalized asset – high cost to install and maintain.
  2. Risk – Critical to the movement of people and commerce – high consequence of failure.
  3. Life-Cycle – Long-term asset with long-term life expectancy – Can be managed using a life-cycle or Inspection-based approach.

Pavements have a long history of research and empirical data models that have been developed for Airports, Parking lots and Roads and a variety of software exists to support the maintenance of this asset.  Therefore, it is pretty easy to choose an approach to manage pavement based on an agency’s goals and priorities.  Typically this program is inspection-driven (every 3-5 years) and focuses on finding the best mix of Preservation and Rehabilitation activities designed to achieve their target Level-of-Service.

Signs

  1. Financial – Capitalized asset – low to high cost to install and maintain.
  2. Risk – Critical to the safety of people and commerce – low to high consequences of failure.
  3. Life-Cycle – Medium to long-term life-expectancy – Can be managed using a life-cycle or Inspection-based approach.

Signs have less empirical data collected for them and can have varied Financial, Risk and Life-cycle information compiled and available throughout the industry.  Strategies for management are typically focused on Life-Cycle and Risk and there are many methodologies that are accepted by FHWA.  These are outlined in their Manual on Uniform Traffic Control Devices (MUTCD) and are widely utilized throughout the US.

Light Poles

  1. Financial – Capitalized asset – medium cost to install and maintain.
  2. Risk – Semi-Critical to the safety of people and commerce – low to high consequences of failure.
  3. Life-Cycle – Medium to long-term life-expectancy – Can be managed using a life-cycle or Inspection-based approach.

Light poles are typically managed by inspection of their base attachments (every 10 years or so) but many agencies typically run these assets to failure (luminaire failure or pole failure).  This is another mixed bag of management because some light poles provide a critical safety function (DOT) and others just light the way for safety (walkways) and are not as critical to the daily operations of an agency.

These are just a few examples of strategy development – we would love to see comments related to the infrastructure that you manage and we will reply with some of the Industry’s Best-Management-Practices (BMPs) that are successfully used throughout the US.

Roadway Characteristics Inventory for DOTs Using Mobile LiDAR Technology

Roadway Characteristics Inventory for DOTs Using Mobile LiDAR Technology

DOTs across the Country are mandated by the Federal Government to keep track of their roadway assets and to report against these assets to receive Federal funding for their maintenance and repair. Many DOTs conduct Roadway Characteristics Inventories (RCI) on an annual basis to update and maintain their data relative to these assets. Traditionally, this has been completed using a boots-on-the-ground approach which has been very effective at building these inventories. Many DOTs are experimenting with other technologies, namely mobile LiDAR, to conduct these inventories and to achieve many other benefits from the 3D data captured in the process.

The next graphic illustrates the typical technology solution utilized for these projects. It is composed of the Riegl VMX-450 LiDAR unit, coupled with High-definition Right-of-Way (ROW) imagery. This system can collect at rates up to 1.1 KHz (1,100,000 pts/sec) at a precision of 5mm. It collects points in a circular (360-degree) pattern along the right-of-way from 2 scanner heads facing forward and to the rear of the vehicle in a crossing pattern. The laser captures 3D points at a density of 0.3 foot at speeds up to 70mph. This scanner can be adjusted to scan at a rate that is applicable for the project specifications to limit the amount of data collected and to ensure that the resulting point cloud data is manageable.

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Right-of-Way imagery is also co-collected along with this LiDAR point cloud data. These images are used to identify appropriate attribution for each feature type being extracted from the point cloud. In this example, the DOT has digitized Shoulder, Driveway Culvert Ends, and Drainage Features (Culverts, Ditches and Bottom of Swale). Additional Features such as Signs, Signals, Striping, and Markings will also be extracted and then reported to the Feds on an annual basis. The mobile LiDAR data provides a 3D surface from which to compile the data and then the ROW imagery can be used for contextual purposes to support attribution. This methodology provides an effective process that can be used to create 3D vector layers and accurate attribution used to build a robust Enterprise GIS.

Both the ROW imagery and the mobile LiDAR can be used to collect and extract the RCI data efficiently for the DOTs and provides the DOT with a robust data set that can be leveraged into the future. The ROW imagery is typically used to map features at a mapping-grade level while the LiDAR can vary a bit in accuracy. Since the relative accuracy inherent in the LiDAR is very precise, it is used to conduct dimensional measurements related to clearances, sign panel sizes, lane widths, and other measurements that require a higher precision.

The DOT utilizes the derivative products from this RCI exercise to report to the Feds in a way that is pretty basic, but effective to achieve their level of funding. For example, the data capture is very technical in nature and focuses on high precision and accuracy. Then, the RCI data is extracted from this source data, maintaining a level of precision that is dictated by the source data. Then, the DOT takes this precise data and aggregates it up to a higher level and reports the total number of Signs or the lineal feet of guardrail. Even though the reporting of this data is pretty basic in nature, the origins of the data can still have precision and accuracy and can be used for other purposes related to Engineering Design or Asset Management.

In conclusion, mobile LiDAR and Right-of-Way imagery are a safe and accurate way to collect and report against RCI variables for DOTs. This methodology promotes a safe working environment for both the DOT worker and the traveling public. It is also a cost-effective way to collect large amounts of 3D point cloud data which can be utilized for other purposes within the same Agency.

Work Bundling for Utilities

Many utilities collect their infrastructure inspection data using a variety of techniques, sources and systems of record.  Having many different repositories of digital information makes it difficult to make informed decisions about where to spend operations and maintenance (O & M) and capital project dollars.  Having a “crystal ball” that aggregates all of this data into one single user interface could help these utilities make more informed decisions for their infrastructure as a whole, instead of using one inspection type to make these decisions.

For example, utilities typically collect information related to their structures and spans using one or a combination of these inspection techniques:

  1. Patrols
  2. Corona
  3. Infrared Inspections
  4. Climbing Inspections
  5. Walking Inspections
  6. Vegetation Points-of-Interest (LiDAR and Visual) Inspections
  7. NERC encroachments (LiDAR) Inspections
  8. Comprehensive Visual Inspection (CVI)

All of these inspections generate a large amount of data independent of one another and can be very useful if combined based on a unique structure or span number.  Once combined, this information can then be used to determine the best way to bundle work activities to achieve the greatest return-on-investment (ROI).

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Work bundling is a concept that has been well understood in the utility industry but not commonly practiced due to the disparate ways in which inspection data is collected and accessed from within a single agency.  Many work management systems only focus on the recording of work order information related to the labor, equipment and materials used to perform a project, but do not contain strategic planning tools.  These tools allow an agency to conduct “what-if” scenarios by applying different budget amounts against a planned work matrix.

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Once the optimal work matrix is determined, a workplan for that utility can then be planned and programmed, executed and tracked as a project or a series of projects for that planning horizon.  All costs related to that work matrix can be applied to each asset and tracked against an overall workplan budget.  These actual costs are then compared to the estimated costs to refine the planning matrix unit costs that are feeding the budget forecasting model.

As an agency completes the work for that particular period, it can then record the work activities against a particular asset which determines its next activity that is due in its life-cycle.  As this feedback loop is established, more cyclical work can be planned and programmed for future fiscal years and budget plans.

This concept has been applied at many utilities through the US using an asset management software called VUEWorks.  This software is GIS-centric at its core and allows users to connect their GIS data to their asset management system through the use of Esri GIS software.  The utility creates a map service which is consumed by VUEWorks and provides a mapping framework from which users can view inspection data from various sources.

For example, a helicopter inspection company collects CVI data by flying next to the transmission structures and collects high-resolution imagery of any defects located on that structure or its associated span.  Another vendor collects walking inspection information which includes subterranean excavations around a structure and its supports.  These inspections yield different defects which may require different types of activities to correct them.  This is where the concept of work bundling can be used.

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Since each inspection yielded different defects, the structure or span will need to be worked on at some point.  It is important that all departments responsible for line maintenance understand all of the defects present on a particular structure or span so that they can conduct all work activities at the same time.  In essence, VUEWorks provides this exact information, all in one place.  The utility has the ability to link all of this data together based on a structure or span ID and can then view all inspection data from one single user interface.

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This concept is important because if a utility needs to de-energize a line for maintenance or capital improvements, it will want to ensure that all issues are resolved during one outage.  Multiple outages cost money and this concept of work bundling is helping utilities achieve high ROIs for these projects by combining projects into one single project, instead of multiple projects.

In conclusion, the concept of work bundling saves utilities time and money through the aggregation of data into a single user repository.  This information can easily and effectively be used to make informed decisions and avoid multiple outage situations.  By combining multiple inspection data sets together, utilities can more proactively manage their assets cost-effectively while extending the useful life of their infrastructure investment.

Transmission and Distribution Utility Infrastructure Capital Planning; A LiDAR and GIS-Centric, Data Fusion and Risk-Based Prioritization Approach

Introduction

Now that the NERC alert bubble has burst, the transmission and distribution sectors of the power industry has a wealth of information that can be leveraged to enhance their business operations. Most power companies are using LiDAR, Imagery and GPS data to collect detailed information about their infrastructure and this information can be leveraged to develop a GIS-centric Asset Management database. So, what can an agency do to leverage this information, especially when it comes from multiple vendors, sensors and vintages?

First, it is important to find the common denominator between all of the data the agency is working with. Utility data typically uses a Structure ID or Span ID that can be used to tie all of this information together from a database perspective. The location of the Structure or Span can also be used to tie information together geographically from a mapping perspective as well as temporally for those agencies collecting information annually or as part of a particular inspection time series.

Next, the agency can visualize all of this information spatially utilizing a GIS so that spatial patterns can be observed. Typical spreadsheet-based deliverables are missing the spatial relationships that can be used to develop better maintenance and operation plans by observing how assets interact with one another. This spatial perspective adds another valuable dimension to help agencies prioritize where to spend their limited resources.

Finally, a Risk-Based prioritization model can then be developed to help the agency decide where to spend their limited funding resources. The assets that pose the highest risk score based on the Probabilities of Failure and the Consequences of those failures can be prioritized, thus limiting the risk to the agency based on these types of failures.

LiDAR Data Collection, Utility Asset Extraction, and Inspection Data Aggregation

LiDAR data can be captured from fixed-wing aircraft or helicopter platforms, depending on the required resolution of the data. Most agencies are interested in capturing information about features that are located within the right-of-way of a powerline or its associated structures. These features are classified in the point cloud and then modeled using encroachment measurement criteria to identify potential hazards to the powerline infrastructure.

The LiDAR point cloud can be used to model the existing as-built structures, tops of towers, conductors, as well as the bare-earth ground model of the area. This information is then loaded into PLS-CADD software and modeled at a maximum load (sag) and maximum blowout conditions. Any LiDAR features that intersect with these “safe zone envelopes” are flagged as encroachments and will be highlighted in the PLS-CADD reports. These reports are exhaustive in terms of the amount of good information contained within them, but can be overwhelming to an agency when trying to figure out “where” to start focusing their time and resources on corrective actions.

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Once all of this analysis has been performed, these encroachment features can be geospatially located and mapped for further analysis. For example, vegetation encroachments can be identified as either “grow-in” or “fall-in” potentials and these points are classified as such.

Vegetation Encroachment Management

GIS mapping provides the user the spatial context necessary to make informed Operations and Maintenance decisions.  As an example, the location of vegetation encroachments is known and with a little manipulation, the volume and area of the vegetation can be determined very easily.  This gives an agency the ability to control the costs associated with their vegetation management program.  Since the agency knows so much about their encroachments, they can very accurately determine the volume of vegetation that needs to be removed.

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The agency also knows other geospatial characteristics of the vegetation units and can then apply specific cost factors to the removal process.  In addition, GIS also provides a great way to provide contractors with maps and exhibits that will help them generate more accurate bids based on relevant information.  A typical vegetation removal contract is assigned to a forestry company who heads to the field and clears vegetation based on their perception of what needs to be removed.  Now, agencies can tell the forestry companies exactly how much (estimated) vegetation needs to be removed and WHERE it is.

Risk-Based Asset Prioritization of Work Activities

Once your agency has identified where the encroachment issues are, how do you design a plan of action that gives your agency the biggest bang for your buck? In other words, there may be a section of powerline that contains many different encroachment types – Vegetation, Building, Ground Clearance, etc. Another section of line may only have Vegetation encroachments. The agency is most likely handling the corrective actions for these issues out of multiple departments and for good reason. Each type of encroachment brings its own set of design standards or engineering challenges to the table and all of these needs to be considered when designing a corrective action program for the facility.

One criterion that can be applied to this information is the concept of Risk.  Risk takes into consideration the consequences of failure of a particular asset and then provides a Criticality Index for specific Asset Classes and Asset Types.  The more critical the Asset – the higher the priority it gets when determining an agency’s primary work focus.  In other words, this concept helps to identify the most critical components of your infrastructure and helps you to prioritize its maintenance over less critical assets.  By prioritizing using Risk, an agency can take measures to minimize the Risk that exists in its Asset portfolio by fixing these pieces and parts first.

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Risk models can be very complicated or very simple. It is dictated based on the information you wish to maintain moving forward and can use multiple automated inputs to help ease the data management strain moving forward. For example, an agency is using their LiDAR information to calculate the risk to a facility based on the number of LiDAR points that have been identified as encroachments as well as their height above ground; the higher the point, to more risky it is to the facility. In other words, the higher the vegetation feature, the more risk it poses to the facility. Since LiDAR data is composed of 3D points, the densities of these points can be applied to the facility’s risk score and then used to help prioritize the facilities that need the most work immediately.

Developing a Project Matrix and Estimating Costs Using Budget Forecasting

Once the facilities have been prioritized using the Risk concepts described above, the agency can then start planning for the actual work activities that will need to happen as part of their annual capital improvement planning activities. This can be achieved by using the Risk scores to determine which facility needs to be worked on and how much it will cost to improve that facility.

First, the facility components can be modeled from the LiDAR point cloud. As a simple example, we can imagine a distribution facility composed of a wood pole, conductors, cross-arm, guy wires and associated hardware. Each one of these facility components has a cost component associated with it based on the materials used and the characteristics of how it was constructed. The cost of materials can then be applied to each component and an overall facility cost can then be determined for the asset.

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Once the facility templates are constructed, the agency can then start developing projects to improve or replace these facilities based on the results of the inspection information. This activity will allow the agency to determine the cost of a project in relation to their annual maintenance and operations budgets and then determine what they can improve for that fiscal years’ time frame.

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All of this information can then be used to determine future years’ capital improvement plans based on funding availability and projected costs over time. This helps the agency to plan for future fiscal expenditures using a repeatable and defensible model that can be applied to different Asset Classes and Asset Types. In other words, multiple, disparate data sources can be fused to support the risk-based prioritization of work activities.

Utilizing Mobile LiDAR to Support Pavement Resurfacing

Many Departments of Transportation are looking for ways to save money while increasing safety on the roads. In order to do this, they are seeking out innovative ways to do this while utilizing new technology. Mobile LiDAR is being used to determine roadway geometry information for long stretches of roadways that are candidates for resurfacing. The typical DOT procurement process involves the selection of a resurfacing vendor through a competitive bid solicitation and then the selection of the most qualified and “cost-effective” bidder. As budgets have become leaner, the competition for these projects has increased and thus, drives the innovation curve to find the most cost-effective solution for the DOT.

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To achieve this goal, pavement vendors have sometimes turned to the use of LiDAR information to develop their bid packages for the DOT. Historically, vendors would use the as-built information that was available from the DOT which might be inaccurate, old or obsolete. This obviously leads to issues with the information that the pavement vendor uses to develop their bid packages. They are most interested in determining the correct amount of cut/fill needed to resurface the road while using the least amount of new material. One of the most important pieces of this puzzle relates to the cross-slop of the road which facilitates roadway drainage and ultimately makes a road safer for the traveling public.

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Mobile LiDAR provides a high-precision, digital terrain model of the roadway surface that can be used to generate very accurate cross-slope measurements at specific intervals. For example, the road surface is continuous for the entire length of the project. Cross-Slopes can be generated for each travel lane as well as for the shoulders. The extracted cross-slope is then compared to the design specification and colored based on whether it is in compliance or out of compliance.

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Once the areas have been identified that are out of compliance, it is easy for the pavement vendor to target those for the re-design effort. Instead of applying an average value across the entire section of road, specific areas can be identified and re-designed so that the pavement vendor can save the DOT money on materials. The ultimate benefit for both the pavement vendor and the DOT lies in the fact that everyone benefits – Pavement vendors can design roads more accurately and limit their risk of material over-runs while the DOT can select the most cost-effective vendor and have more budget available to pave their ever-increasing network mileage of roads.

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Since mobile LiDAR data is very cumbersome to manage (2Gb/mile) it is important to deliver the data in a format that is usable by the client. Sometimes raw LAS files work and sometimes the client can only deal with vector files that will be used in GIS, Autocad or Microstation, to name a few. We have found that KMZ files are useful as a delivery mechanism because they can be easily loaded and viewed by the client in very short order. Any derivative of these delivery mechanisms will work – it just depends on the expertise of the client and their computing environment.

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Future discussions will focus on the DOTs and their collection of mobile LiDAR data so that they can provide it to all of the pavement vendors and receive the most cost-effective bid packages. Although there is an up-front cost associated with the LiDAR collection, it is believed that the downstream cost savings for both the DOT and the pavement vendor will more than outweigh the up-front cost of collecting the mobile LiDAR data.

Sign Retroreflectivity Compliance and Asset Management

Over the past few years, there have been many projects designed to determine an agency’s sign retroreflectivity compliance across their road network. Each project has been unique in terms of how the agency collected the data and how they ultimately managed the data into the future. Recent MUTCD regulations require the development of an inventory management program that documents the installation, maintenance and construction characteristics of sign infrastructure. Many agencies are faced with the daunting task of funding a replacement program that will comply with these new regulations into the future. Ultimately, the replacement plan needs to address non-compliance issues that are identified during the inventory/inspection process.

Step 1 – Sign Inventory

The first step in the compliance process begins with an accurate inventory. Signs can be collected utilizing many different techniques and each technique can have its pluses and minuses. Field collection programs can involve inspectors walking the roads, mobile imaging vehicles taking pictures of the roads as well as other collection techniques designed to identify compliance issues along the road. No matter which solution is selected, it needs to satisfy the overall goals and objectives of the project while providing an accurate inventory of the agency’s sign infrastructure.

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Next, an agency needs to be able to match their available funding to the technology solution that achieves their project goals and objectives. It also needs to understand the trade-offs that are the necessary evil in projects like this – available funding typically dictates the quality of the solution that can be provided by the service provider. Furthermore, the quality of the data collected and its usefulness can be impacted by the choice of the solution and available funding.

Remember that the ultimate goal of retroreflectivity compliance is centered on the replacement of signs once they fall below the minimum reflectivity standard as defined by FHWA. Many agencies would rather start replacing signs today instead of spending money to create their inventory and a management plan. This makes sense economically in the short-term, but can introduce problems from a long-term management perspective.

Step 2 – Estimating the Replacement Cost of the Sign Network

The next graphic illustrates the total replacement cost as calculated using the FHWA “Sign Retroreflectivity Guidebook” for an agency with a 4,383 centerline mile road network.

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The cost to replace all signs for this agency approaches $17.5 million dollars. Please note that this does not include the cost of the labor, equipment and other material costs incurred for the actual installation of these signs. The inventory of signs for this agency cost approximately $800k or roughly 5% of the total replacement cost for these signs. Although significant, this investment is crucial to ensure the longevity of the Sign Management program designed to manage these assets throughout their life-cycle.

Step 3 – Choosing a FHWA-Approved Sign Management Methodology

The chart below illustrates the advantages and disadvantages related to a few of the FHWA-recommended methodologies. Most of these methods have been implemented in one way or another at various agencies across the Country.

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The “Measured Retroreflectivity” method is popular at many DOTs and Toll Authorities. I believe this is the case because these agencies typically manage facilities that carry higher volumes of traffic that operate at higher speeds, thus increasing the risk and potential consequences of an accident. Many County and City agencies are utilizing the “Visual Nighttime Inspection, Expected Life, Control Sign, or Blanket Replacement” methods to manage their sign infrastructure. Each mentioned method is used for different reasons (financial vs. headcount) and has a lot to do with legacy management techniques (“We’ve always done it this way”).

There really isn’t a management method that can be considered “The Best” or “The Most Cost-Effective”. It is solely dependent upon an agency’s goals and objectives for the management of their sign infrastructure. I typically recommend conducting an inventory first and then implementing a management plan that uses the concepts of Condition, Risk, and Valuation to help prioritize which signs should be replaced along with the best timing for the replacement. This can prove very valuable since the highest risk signs can be replaced first and the least risky signs can be programmed for replacement as funding becomes available.

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Finally, I also recommend that agencies utilize asset management software to manage the work performed on their sign infrastructure so that all replacements can then be managed according to their useful life and actual condition rating. This information can then be used in concert with one another to help develop a capital improvement plan that details the planned fiscal expenditures for the next 10 years, which is the typical life-cycle of a sign.