LCCA is an analytical technique that uses economic principles to evaluate long-term alternative investment options for highway construction. This process has been an integral part of agencies’ decision-making process for selecting different pavement types, rehabilitation strategies and pavement design life for many years [
8]. It was ushered into the transportation domain in the 1960s through the works of engineering economist Winfrey and the American Association of State Highway and Transportation Officials (AASHTO) “Red Book” [
9,
10]. In the 1980’s the federal government endorsed the use of LCCA as a means for economic evaluation [
11] and presented LCCA state-of-practices in transportation agencies [
12]. The 1992 Intermodal Surface Transportation Equity Act suggested LCCA be considered in highway construction and the National Highway System Designation Act of 1995 mandated its use on projects larger than
$25 million in value [
8].
Although the mandated use of LCCA was rescinded by the USA 1998 Transportation Equity Act for the 21st Century (TEA-21) [
8], using LCCA as a decision support tool is still advocated by the FHWA. This is depicted through the FHWA publications such as the LCCA in Pavement Design Participant’s Notebook [
13], Interim Technical Bulletin [
14], Life-Cycle Analysis Primer [
8], NCHRP Report 703 on Pavement-Type Selection [
15], NCHRP Report 483 on Bridge LCCA [
16] and NCHRP Synthesis 494 on highway LCCA practices [
3]. These documents have successfully promoted the use of LCCA and provide guidance to agencies as described below.
2.1. US Federal LCCA Process for Highway Construction
The FHWA LCCA suggested practices have been disseminated to state agencies through publications previously listed. The first step in the LCCA process is the decision to perform an LCCA. TEA-21 requires value engineering be performed for all projects over
$25 million and recommend that LCCA be a part of the value engineering reviews, though it is not currently mandated [
8]. Once the decision is made to pursue LCCA, it must be conducted as early as possible, FHWA suggests during the project design stage [
14].
The inputs for a pavement design LCCA are very robust and typically include but are not limited to, the following: discount rate; annual growth rate of traffic; free flow capacity; value of time for passenger cars, single unit trucks and combination trucks; agency construction and maintenance costs; user work-zone costs, work-zone capacity and work-zone duration; maintenance frequency; activity service life; and uncertainty/risk data as applicable [
3]. Once a project is selected for LCCA, FHWA’s suggested process has eight steps: (1) establish alternative pavement design strategies; (2) determine performance periods and activity timing; (3) estimate agency costs; (4) estimate RUCs; (5) develop expenditure diagrams; (6) compute net present value; (7) analyze results; and (8) reevaluate strategies [
14].
2.2. Life-Cycle Cost Analysis Existing Literature
Efforts have been made to document LCCA state-of-practice for highway construction across the US (i.e., Peterson [
12], Zimmerman et al. [
17], Ozbay et al. [
2], Rangaraju et al. [
18], Babashamsi et al. [
19], Flannery et al. [
3]) though implementation still varies significantly from state to state. To aid agencies in their LCCA implementation, existing literature has also been dedicated to optimizing the process models. Early research in pavement LCCA was dedicated to proposing models that analyzed pavement life-cycle costs [
9] and optimized life-cycle disutility, the ratio of costs and performance [
20]. Research has continued to build upon the foundational LCCA models, adding uncertainty-based approaches to handle the input variabilities and project risks [
21,
22,
23,
24] and incorporating variables such as energy consumption and greenhouse gas emissions in the analysis Zhang et al. [
25]. Despite literature’s attempt to aid agencies, in an investigation of the differences between state-of-practice and state-of-art, Ozbay et al. [
2] found several gaps between the theoretical and actual LCCA applications including the treatment of uncertainty, timing of future rehabilitation activities and the inclusion of RUCs.
The issue of the inclusion of RUCs into the LCCA process is echoed throughout literature. Calculation of RUCs is the area that agencies are most significantly lacking in their LCCAs (Peterson [
12], Walls and Smith [
14], Papagiannakis and Delwar [
4], Ozbay et al. [
2], Yu et al. [
6], Morgado and Neves [
25], Babashami et al. [
19], Flannery et al. [
3]. Existing literature also depicts between 50% to 70% of agencies are not incorporating RUCs in their LCCA analysis [
2,
3]. There is some contention that RUCs hinder the LCCA process [
25] but literature generally agrees that RUC are required for an accurate LCCA. The NCHRP Synthesis 494 goes as far as to say that “one of the great advances in public-sector infrastructure management and decision making has been the more widespread assessment and inclusion of RUCs …” [
3].
Morgado and Neves’s [
25] contention of RUC comes from the finding that on highly trafficked roads, RUCs can often be the determining factor in choosing a project, negating the true purpose of the LCCA. To combat this, both Morgado and Neves [
25] and Heravi and Esmaeeli [
26] introduced multi-criteria decision tools into pavement LCCA that weighs, among other attributes, RUCs. Alternatively, Papagiannakis and Delwar [
4], Zheng et al. [
5], Yu et al. [
6] and Lee et al. [
7] developed models that incorporated RUC models into highway agency decision-analyses, especially converting RUC to agency costs equivalent with some discount-factors. Papagiannakis and Delwar [
4] presented one of the early computer software programs, outputting the net annualized savings in RUCs from reducing pavement roughness. Zheng et al. [
5] incorporated two RUC tools, MicroBENCOST and HDM-4, RUC tools, into the current Canadian asset management system and compared their ability to output RUC-benefit analyses. Yu et al. [
6] also presented incorporating work-zone RUCs into China LCCA cost models, relying on agency computations versus software for costs and impacts. Lee et al. [
7] presented the use of RealCost and CA4PRS as LCCA tools, validated through the California Interstate 710 Project in Long-Beach (Phase 1), the 1st long-life ACP reconstruction in California.
All these are important additions to the current body of LCCA highway pavement design literature though none properly discuss RUCs integration into the current agency LCCA process. Both Morgado and Neves [
25] and Heravi and Esmaeeli [
26] attempt to mitigate road user impacts through multi-decision analyses yet do nothing to increase the RUCs accuracies. Papagiannakis and Delwar [
4] present a maintenance/rehabilitation decision tool but do not incorporate it into the existing highway LCCA. Zheng et al. [
5] review two RUC estimation processes but incorporate them into a benefit-cost analysis not the LCCA process with NPV (net present value) calculation and merely focus more on the comparison of the two models than their use as a LCCA tool. Yu et al. [
6] work is meant for Chinese implementation and not state-of-the art in the US. Lee et al. [
7] present the use of RealCost and CA4PRS to perform a LCCA but fail to present how it is incorporated into the existing highway construction LCCA process.
The integrated model presented is a contribution to the LCCA body of literature in mitigating RUC inaccuracies through state-of-the-art programs, backed by the FHWA and already in use for many agencies. Unlike previous LCCA literature, this model was also validated through implementation into a working project from the scoping phase. This paper builds off Lee et al. [
7] existing research, by integrating the existing suggested FHWA LCCA process.