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Case Studies

Transportation agencies across the United States are using INVEST to evaluate and improve sustainability within their agency and on their projects.

Case studies focus on the general use of INVEST and its implementation and/or scoring practices. Some focus more on process/application, some focus on a few select criteria, some focus on the overall experience of using INVEST. Case Studies are developed by the agency which submits them, with review and input by FHWA.

Use the map and filters below to find case studies relevant to your projects and/or agency.

DelDOT - Using INVEST to Measure Sustainability for the DelDOT Pavement and Rehabilitation Program

Lead Agency: Delaware Department of Transportation (DelDOT)

INVEST Modules: Operations and Maintenance


 Download the DelDOT Case Study (206 kb)

DelDOT used the INVEST Operations and Maintenance (OM) module to score its Pavement and Rehabilitation Program and other OM activities. Even though DelDOT has actively employed sustainable practices (such as the use of recycled materials) for over 20 years, the agency had never quantified these efforts prior to INVEST. By using INVEST, DelDOT was able to measure the sustainability achievement of its Pavement and Rehabilitation Program and identify areas for improvement across many aspects of project delivery. Some of the INVEST OM criteria addressed DelDOT or statewide initiatives not specifically associated with the Pavement and Rehabilitation Program, which focuses specifically on pavement preservation. In those cases, DelDOT gathered information from the other relevant program areas to complete the evaluation.


To do the scoring, DelDOT brought together several subject matter experts within the agency, including representatives from the following sections: Planning, Traffic Safety, Business Management, Maintenance and Operations, and Engineering Support. With the combined input from the subject matter experts, DelDOT calculated a score of 146 out of 210 possible points, as displayed in the chart below, which equates to the platinum level in INVEST.

Highlights from Specific Criteria:

Sustainability highlights from the OM INVEST evaluation included:

  • OM-7 Pavement Management System and OM-8 Bridge Management System. DelDOT scored very highly on these criteria because the agency has extensive pavement and bridge management systems that track performance and condition across the State. DelDOT uses the data to inform and prioritize maintenance actions. The summary information is also available to the general public via a dashboard on the DelDOT website at
  • OM-4 Recycle and Reuse. DelDOT did not score as highly on this criterion, even though the agency has employed these practices for decades. This is because the agency does not yet have a formal mandate or target for construction material recycling. Despite the lack of a formal target, DelDOT has incorporated recycled materials, including recycled asphalt pavement, recycled asphalt shingles, recycled concrete aggregate, tire-derived aggregate, crumb rubber, cellulose fibers, and plastic from bottles for over 20 years in highway construction. DelDOT also has used industrial byproducts, such as ground granulated blast furnace slag, silica fume, and fly ash in the Portland cement concrete used for projects. In the past decade, DelDOT has also used in-place roadway reclamation and recycling operations for maintaining roadways. The process keeps pavements in place for pulverizing, stabilizing, and reshaping while minimizing the construction footprint of the work. The reclaimed and recycled pavement provides a stable construction platform for the overlay of structural pavement materials. DelDOT will investigate opportunities to formalize the commitment to recycling and reuse through agency targets.
Criterion Points Scored Maximum Points Possible
OM-01 Internal Sustainability Plan 8 15
OM-02 Electrical Energy Efficiency and Use 5 15
OM-03 Vehicle Fuel Efficiency and Use 11 15
OM-04 Recycle and Reuse 6 15
OM-05 Safety Management 13 15
OM-06 Environmental Commitments Tracking System 13 15
OM-07 Pavement Management System 15 15
OM-08 Bridge Management System 15 15
OM-09 Maintenance Management System 7 15
OM-10 Highway Infrastructure Preservation and Maintenance 10 15
OM-11 Traffic Control Infrastructure Maintenance 2 15
OM-12 Road Weather Management Program 15 15
OM-13 Transportation Management and Operations 13 15
OM-14 Work Zone Traffic Control 13 15

Lessons Learned through INVEST Evaluation:

DelDOT identified many areas where it was performing well with respect to sustainability, but the agency also identified some potential future improvements, such as the following:

  • OM-01 Internal Sustainability Plan. While senior leadership within the State is committed to sustainability, there are opportunities to improve tracking and monitoring in some areas. For example, although DelDOT recycles materials, the agency has not yet tried to measure the extent and impact of recycling.
  • OM-02 Electrical Energy Efficiency and Use. DelDOT (and the State overall) has targets for reducing energy consumption and increasing renewable energy use statewide. DelDOT can use the results of this module to advance those goals while balancing the economic impacts.
  • OM-03 Vehicle Fuel Efficiency and Use. The State has set goals to reduce fossil fuel use and DelDOT has used alternative fuels for their fleet. However, DelDOT plans to increase the use of alternative fuels in fleet vehicles where available and economically practical.
  • OM-04 Recycle and Reuse. Based on this criterion, DelDOT has identified an opportunity to establish recycling and/or reuse targets for construction materials and/or industrial byproducts. DelDOT already implements recycling and reuse, but has not yet set targets.
  • OM-11 Traffic Control Infrastructure Maintenance. DelDOT policy requires traffic control plans. However, they are project specific, do not include performance metrics, and do not explicitly reference sustainability. DelDOT plans to review this area and consider improvements based on the INVEST evaluation.

Key Outcomes of Using INVEST:

The INVEST OM scoring module helped DelDOT to identify several opportunities to enhance the agency’s sustainability efforts. Now DelDOT plans to further assess and pursue these improvements. DelDOT also plans to conduct subsequent evaluations of its programs with the INVEST System Planning and Project Development modules. The future outlook is promising based on senior leadership’s commitment to sustainability both within DelDOT and across the State.

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