Pavement Managers will tell you that the most important aspect of a road is the base, from which everything else can be built. In our newest series, ESA Essentials, our goal is to provide a strong base of knowledge for users of the IMS Easy Street Analysis application. In this series we will cover all of the essential elements to the ESA pavement analysis software, preparing new and experienced pavement managers, alike, with a strong foundation that provides both clarity and confidence to future pavement management decisions.
This article is a companion piece to the video which can be found in the link below:
New to Easy Street Analysis
If you are reading this guide than you are probably already aware of the purpose behind the IMS Easy Street Analysis pavement management software, but you may not be aware of the extent of its management capabilities. In this series we will cover all the basics to get your team started.
While the results of a pavement management survey can certainly be documented into a final report that illustrates the findings, IMS believes it is imperative that City staff have access to the pavement condition and analysis results without having to become software experts themselves. That is why Easy Street Analysis exists as a fully functional pavement management program that is housed in user-friendly, interactive spreadsheet.
In this first article we will cover some of the tabs users will want to understand the very first time they open ESA.
Keeping Tabs on ESA
The first tab you are likely to see when opening ESA is known as the “Tab of Tabs”. It is simply and index of the various tabs available in the program, with details on each one. Keep this in mind as an index if you happen to be looking for specific information or functionality.
The Summary Tab – As Mark Kramer puts it in the companion video to this article “This is where you will find answers to all the questions your managers office, directors or council members will ask.” It includes facts about the network, such as mileage and PCI of each functional class as well as total network backlog percentage and total mileage. This is a great starting place to pull some basic information about your networks condition.
Definitions – The pavement management industry is full of acronyms that you will find throughout ESA as well as in a pavement management report. This tab is a quick refresher just in case you forgot what, say, "FWM" stands for. (Full Width Mill)
Comps – This tab includes some quick budgeting estimates that can be helpful planning tools both before the analysis is completed, and to check the results of the completed analysis. These are often referred to as “bar napkin math” estimates, but don’t let that fool you. They are often very accurate in determining a budget range that the city should strive to meet. There are 3, one based on total network value, one based on average condition, and one based on various rehab rates for your city and the surrounding area.
$Plot – This is your asset value estimate tab. Here you will see the breakdowns of reconstruction costs for your entire network, as well as its estimated total value. We like to refer to the pavement network as the most valuable visible asset in a city. This tab will demonstrate why that is the case by breaking down construction costs.
Equity Removal – The chart on this tab breaks down the costs associated with underfunding at various budget levels. The idea is that an underfunded pavement network will accrue additional costs to the city that will need to eventually be repaid. This table is a helpful visual aid to show the cost of underfunding.
Network Analysis – This is where all of the calculations are done. We will go way more in depth on this tab in a later article, but for now just know that this tab is where you will add planned work and run annual budgets through the analysis.
Parameters – This is where the parameters are set for the analysis. Again, we will focus on this tab much more later, but this is where you will set naming conventions for functional classes / set GFP ranges / identify rehab prioritizations and more.
Rehab Activities – This tab shows a summary of all rehabilitation types as well as rates by functional class. These are usually broken down in cost per square yard.
Inventory – This tab is a collection of every street segment and a breakdown of the survey condition and recommended rehab to restore the segment to full service. Each segment is organized by GISID and includes from and to streets. The condition breakdown also describes each surveyed distress on a 1-10 severity scale.
Rehab by Segment/Year – These two tabs show an export of whatever budget run was most recently done in the network analysis tab. It will show you recommended rehabs and estimated costs per segment and per year.
Helpful Visual Aids
The next selection of tabs will display a series of graphs that are visual representations of the information contained in the inventory and rehab by segment/year tabs:
Annual PCI – This graph shows the resulting PCI at various budget levels
GFP/PCI post rehab – These graphs show the post rehab condition of the network depending on the budget information loaded into the network analysis tab.
Survey PCI and Current PCI – While the survey PCI tab will show the condition breakdown at the time of the survey, the current PCI tab will show the PCI that is aged appropriately to the date that is set in the network analysis tab.
So there we have an overview of some of the tabs that ESA users will become familiar with. That should be enough to digest for now. Next week we will begin our deep dive into the specifics of how to get an ESA analysis up and running for your city, including scheduling planned work manually in the Network analysis tab.
Pavement management is not just about prolonging the lifespan of a road, but also optimizing the effectiveness of a budget. Every municipality has a unique pavement network. There are varying types of construction, pavement types, and functional classes. Many municipalities maintain a network of paved pedestrian pathways or bike paths in addition to their roads. Finding out what you have and what you need is only the first part of the process.
Less than 1% of agencies around the US have an annual budget that is large enough to rehabilitate their entire pavement network to excellent condition within a short 5-10 year window. This means that tough decisions need to be made about which pavement segments require urgent repairs, and which ones can be deferred until a later time. Pavement rehabilitations require significant investments by the city, and so the decision to defer some roads or rehabilitate others is not a trivial one. City managers want to make sure they are making determinations based on data driven factors and sound pavement management principals.
When Data Driven Decisions Save You Millions
The average municipality has nearly 200 centerline miles of pavement surface; divide that up by varying functional classes, pavement types, traffic and distress patterns and you may quickly arrive at thousands of unique pavement surfaces in a single town. All must be considered for potential rehabilitation. That magnitude of factors that require consideration simply cannot be adequately addressed without the aid of pavement management software.
When pavement management software is in use, the entire pavement network with distress and severity can be applied to a model of the city’s budget. This can ultimately provide the city with a proverbial road map of needed repairs based on the unique budget and street network conditions. This data driven process can be easily defended as the best practice, and can often help a municipality secure additional federal or state funding when it is desperately needed.
It is difficult to know what the future holds, but maintaining a 5-10 year plan that is based on best pavement management practices and defensible data can go a long way toward saving your city valuable tax-dollars and improving the level of service in your community.
Want to learn more about setting up a pavement management program in your city? Check out "Designing and Implementing a Pavement Management System" - An IMS Whitepaper
When a municipality seeks to ascertain the overall condition of their pavement network, there are often three primary factors that they consider: Surface Distress Index (SDI, or sometimes referred to as Pavement Condition Index), Roughness Index (RI) and Structural Index (SI). These factors can be combined in order to calculate an Overall Condition Index, or OCI.
While Surface Distress Index is vital and measures the length and severity of surface distresses, Structural Index and Roughness Index are considered enhanced attributes that can improve the reliability of a pavement condition assessment. Structural Index measures the strength of a pavement’s base, but Roughness is focused on something that all travelers will notice; just how bumpy is the street?
In engineering terms, roughness is measured with the International Roughness Index, or IRI. IRI is focused on measuring the change in elevation over a (relatively short) distance, expressed in millimeters/meter. You could also ask, is my road smooth?
When is Roughness Used?
Measuring roughness, often referred to as longitudinal profile, gives municipalities a better understanding of the condition of a particular road, but there are a few places where roughness may not provide the results you are looking for. Roughness that is calculated at extremely low speeds, or over manholes, speed bumps, railroad tracks and the like should be filtered out of a final OCI score. Failure to account for such roadway conditions will result in an inaccurate roughness score that adversely affects an otherwise pristine or newly paved street.
In a semi-automated pavement survey, roughness is measured via a series of gyroscopic sensors. These sensors detect minute changes in elevation over short distances, usually in millimeters per meter. Following a series of calculations that are performed within the pavement management system, a 0 -100 score is recorded. In common terms, a newer street would generally have a Roughness index above 85, while one due for an overlay would be in the range of 40-70. Failed streets typically have roughness values below 40. Some surface distresses such as raveling or rutting can have a large impact on the roughness readings, causing certain surface distresses to have a major impact on the Overall Condition Score once roughness has been included in the calculations.
When roughness is eventually implemented into the final OCI score, it generally accounts for 25-33% of the Overall Condition Score.
To Each Their Own
Though roughness can be a valuable factor in determining the overall condition of a roadway, not all agencies will choose to consider roughness in their final pavement condition score. Some pavement network conditions, such as brick crosswalks, cattle guards, railroad tracks and the like may discourage a municipality from trying to factor in roughness due to the complexities associated with filtering out pavement factors which ultimately crater the final roughness scoring. Additionally some popular pavement management programs, which have been in use by municipalities for years, are not able to factor in IRI readings into a final pavement condition score, leaving a lot of recorded data unused in these cases.
Ultimately roughness can be a very valuable factor to understanding the condition of a pavement network; however, agencies must take care when including roughness and ensure that it is not being used improperly. A meticulous quality control process should be implemented to confirm that roughness factors are not being considered inappropriately and roads are not being punished for their intended design.
For many municipalities around the US the most distressed roadways are likely in need of a full reconstruction. That’s an expensive task. But before you find yourself looking down a multi-million dollar pavement budget hole, take note of a few possible alternatives to reconstructing all of your agency’s failed streets.
Selecting the proper rehabilitation technique for each segment of road and identifying the optimal year to perform this treatment is what pavement management is all about. Factoring in local circumstances such as weather, soil and traffic conditions enables municipalities to determine when a road’s deterioration curve is at its steepest. An experienced pavement management expert will develop a strategy to capture roads before this point, thereby minimizing deferral costs and maximizing limited available funds.
When it comes to pavement management, failed streets that require a full reconstruction have a major difference over all other streets. They will require a full reconstruction no matter how long rehabilitation work is delayed. That means that their cost of deferral is effectively zero (discounting inflation). Compare this to your average local street with a PCI in the low 60s or mid-50s range – this street will gradually increase in repair costs the longer work is delayed. For this reason, municipalities commonly refer to failed streets as “backlog” and frequently allow them to remain in their condition until greater funding is secured.
Let’s take a look at some general rehabilitation rates that will help make this deferral concept clear:
Draw your attention to the colored boxes in the image above. The box that includes “Thin Overlay” (Green) is recommended at a minimum PCI of 60 (marked by the red arrow). The cost associated with this particular rehab activity is approximately $18.00 per square yard.
Directly below the green box is a yellow box; this box identifies “Moderate Overlay” rehabilitation range. The minimum PCI for a moderate overlay is 10 PCI points below the PCI recommended for the thin overlay. Notice the cost difference between the two groups amounts to $3.00 per square yard. This is the cost of deferring a thin overlay candidate for about 5-10 years.
Beneath the yellow box is an orange box which represents “Thick Overlay”. In this grouping the cost per PCI point has jumped from $21 to $32. This $11 per square yard difference represents the cost of deferral associated with going from a moderate to a thick overlay.
Finally, notice the surface and base reconstruction candidates in the bottom red box. The red arrow points to a minimum PCI range of 25 for a surface reconstruction. This rehab activity is recommended only 15 PCI points lower than the thick overlay, and yet, the cost of deferral has inflated to nearly $26.00 at a total of $58 per square yard. This area is the steepest part of a roads deterioration curve and if deferred any longer will ultimately result in a full base reconstruction totaling a whopping $70.50 per square yard.
The rehabilitation activity needed for a road becomes progressively more expensive the longer repairs are deferred; however once it reaches a PCI under 40, surface or full base reconstruction becomes the only viable method to restoring a road to full-service. At this stage, cost effective overlays are no longer a workable rehabilitation option. Further deterioration of a base-reconstruction candidate will not change its rehabilitation prescription; therefore the cost of deferral will not increase beyond this point.
Financially Savvy Deferrals
As shown in the above example, an optimal pavement rehabilitation plan is built around a strategy that minimizes the cost of deferral. Let’s consult the colored chart one more time and see if we can determine the most cost effective way to prioritize our planned work.
If we were to prioritize work solely based on cost of deferral it would look something like this:
However, budget constraints, level of service goals, and even the political environment in a municipality often impact these priorities. For example: when considering budget constraints, one of the more frequent questions that we field on our analysis relates to "fall through year" rehabs. These are streets identified as a need in an analysis year that funding won't cover. Most clients assume that they are prioritized in the next year, but many times they are not. The reason is that, often, these streets drop into the next rehab category. They now have more time in the new rehab category before becoming a "critical" roadway that is within 2-3 points of dropping into the next rehabilitation band. It's all about time left in the current rehabilitation category and which road segments are in their “need year”.
If a particular segment of road is designated for a surface treatment, but the street’s deterioration curve forecasts that it will still be in the rehab category of surface treatment for another 4 years, it should not be prioritized over the moderate overlay candidate that is set to fall into the thick overlay category in the next year. This “Need Year” methodology prioritizes rehabs on a case by case basis, and only selects a road for treatment when it is on the verge of dropping into the next, more expensive, rehab category. This allows municipalities to perform maintenance work on only the segments of road that are an immediate risk of a cost of deferral increase.
The street segments that each municipality selects for rehabilitation can be seen as an entirely unique and case by case process. Each municipality faces its own set of budget constraints, level of service goals, and other local factors that must be considered in this process. It is for that reason that there is no generic “one size fits all” solution. There are, however, some basic considerations that every municipality should think about when it comes to the cost of deferral and rehab selection. By organizing maintenance work along these principles, municipalities can take tremendous steps toward optimizing pavement management funds, and providing the best service possible to taxpayers and residents of their community.
For more tips on managing your pavement budget, check out "Managing a Pavement Budget" HERE.
You probably never imagined how many lives could be saved by simple pavement renewal efforts. In October, 2014 the Federal Highways Administration and U.S Department of Transportation released the results of a 10-year study on fatal car crashing in the United States. A gut wrenching 371,104 fatal crashes occurred in the U.S from 2000-2009. (FHWA, 2014) The report identifies 12.6% of these fatal accidents occurred on wet pavement. The FHWA then asserts a shocking recognition; 70% of these fatal accidents could have been prevented or minimized by simply improving pavement surface friction. That’s 32,730 lives that could have been saved by inexpensive and easily identifiable pavement rehabilitation efforts.
The most commonly deferred roads are those that display only surface distresses, such as raveling (loose pavement material on the surface) or bleeding (excess asphalt binder on the pavement surface). Although these distresses do not reflect an imminent failure of the pavement base, they do reduce tire traction and increase the possibility of a vehicle skidding.
Thankfully there are some easily implemented solutions that can alleviate these concerns and make your roads a safer place to drive.
What never moves and has no feet, but frequently wears shoes, sandals and boots? Sidewalks are one of the most utilized city assets, and yet, simultaneously they remain one of the most neglected. In our 30 years of surveying infrastructure assets in cities across North America, we can say with confidence that the majority of municipalities are struggling with sidewalk compliance and repair backlogs that remain largely underfunded.
Sidewalks can increase public safety, encourage healthy outdoor activity, and even promote economic well-being in low-income communities. On the other hand, when improperly managed, sidewalks can be a tremendous financial drain on a city’s budget. Pedestrians seldom hesitate to file personal injury lawsuits against cities that fail to maintain their sidewalks. There is also the issue of ADA compliance looming over every sidewalk construction project. In addition to managing a backlog of repair projects, settling lawsuits can undermine a municipality’s budget. With this in mind, here are 5 useful tips that will ensure you maintain a happy and healthy pedestrian community:
Some distressed roads need to be fixed right away, some don’t. If you are in charge of a municipality’s pavement management decisions then you have probably been faced with the difficult decision about how to optimize the spending of a limited budget. To navigate those situations with expertise you must be aware of the deferment cost.
In pavement management, road segments are assigned a score depending on their overall quality; this is known as a PCI, or Pavement Condition Index. Depending on the PCI score of a street, pavement management software will recommend a suggested rehab treatment and factor in the average cost. There are a variety of rehab categories to be aware of, all varying in cost depending on the functional classification of the roads in question.
Over 12,000 ASTM (American Society for Testing and Materials) standards are used around the globe, standardizing work in engineering, manufacturing and many other fields. The standards created by ASTM cover everything from construction standards and sustainable design to chemical research and environmental safety. ASTM standard use is ubiquitous across a wide variety of industries, but where do these standards come from?
Preservation of existing roads and street systems has become a major activity for all levels of government. Because municipalities must consistently optimize the spending of their budgets, funds that have been designated for pavement need to be used as effectively as possible. The best method to obtain the maximum value of available funds is through the use of a pavement management system.
A pavement management system is a computerized database that is linked to GIS and contains every individual pavement segment throughout a network. Since it is cost-prohibitive to completely repair every road in a network in one year, a pavement management system should be configured to adequately age particular segments in accordance with their condition analysis (i.e., roads with a weak base deteriorate quicker). A pavement management system is highly recommended to organize ongoing rehabilitation activities because it is common for a network to contain thousands of road segments.
All around the country municipalities are faced with a difficult question.
“How can we provide the best possible service to our community with the limited budget we have?”
When it comes to the pavement network of your city, it should be seen as the most valuable visible asset that the city maintains. Because these assets are constantly under heavy use, municipalities must always be coming up with new strategies and methods for maintaining them. In some cases, street maintenance can be deferred without significantly increasing the future costs associated with needed repairs. In other cases, deferring a street can result in a tremendous increase to the cost of repairs. In pavement management, this concept is referred to as, “equity removal”. Without a sufficient grasp of this important concept, cities risk losing millions of dollars in value from their pavement network.