## 4 Results and Discussion
For example, while CIPPRT hashigher direct costs ($98.8/m), its shorter duration and moderate environmental impact may justify its selection under certain weightings.  
[PERSON] [61] identified eight social cost categories, including travel delays, vehicle operating costs, and lost business revenue. Travel delay costs constituted most of the social costs (\(\sim\)55%). Open-cut construction was $367.25/LF, compared to micro-tunneling at $26.95/LF.  
[PERSON] et al. [79] evaluated CIPPRT, pipe bursting, and OCCM based on cost, pipe diameter, and service reconnection needs. Pipe-bursting costs were over 60% lower than OCCM and the approach was more effective for projects requiring increased service capacity.  
[PERSON] [1] analyzed the CO2 emissions generated by OCCM and pipe-bursting methods. A case study in Bowling Green, Ohio, revealed that pipe-bursting reduced total CO2 emissions by 72.6%, compared to OCCM.  
[PERSON] [80] analyzed costs for OCCM, concluding that agency costs are approximately $856,216 per lane-mile, while trenchless methods significantly reduce costs through minimized surface disruption. Another study compares fuzzy and simulation-based life-cycle cost models for sewer rehabilitation to address uncertainties in costs, service life, and other parameters [64]. It identifies cost-effective strategies for different rehabilitation methods: open-trench/sleeve repairs ($1000-$6600/unit), slip-lining for renovations ($190,000-$385,000/km), and pipe bursting for replacements ($548,000-$5770,000/km). The study found that fuzzy models are more conservative, yielding higher cost estimates, while simulation-based models provide practical probabilistic results which are typically 2-19% lower. [PERSON] et al. [81] emphasized the economic and environmental benefits of trenchless methods. Pipe bursting showed higher emissions per 100 m (0.96-5.10 tons CO2), compared to CIPPRT (2.66-3.11 tons CO2). Reference [82] used three carbon calculators to assess the carbon footprint of trenchless methods. CIPPRT emerged as the more carbon-efficient option. [PERSON] et al. [83] used ReCiPe 2008 H/H to evaluate traditional and pipe-bursting systems, concluding that pipe-bursting generally had lower environmental impacts due to reduced greenhouse gas emissions. [PERSON] et al. [84] analyzed the carbon footprint for a 150-mile Integrated Pipeline (IPL) Project. Prestressed concrete cylinder pipes had a 15-20% lower carbon footprint, compared to steel pipes. [PERSON] [85] investigated OCCM and trenchless tunneling methods for constructing a 250-mile Underground Freight Transportation system in Texas. Tunneling was found to be suitable for urban areas due to its minimal surface disruption, while open-cut methods were cost-effective in rural areas. [PERSON] et al. [86] compared the carbon footprint of open-cut and trenchless methods. Open-cut methods produced 5379 tons of CO2 for each 25 miles compared to 887 tons for trenchless methods. [PERSON] [87] compared open-cut, horizontal directional drilling (HDD), and auger boring methods. Open-cut was the least expensive, at CAD 200 per meter, but incurred higher social and environmental costs. These findings suggest that decision-makers should consider the three main impact factors--direct cost, social cost, and environmental impact--when selecting pipeline materials and installation methods [48]. OCCM requires extensive construction equipment for trench excavation and additional backfill materials, resulting in higher energy consumption during installation. In contrast, CIPPRT is the most environmentally friendly option, requiring minimal equipment and smaller excavation areas. The ASCE [88] has emphasized that optimizing pipe manufacturing processes, improving construction methods, and reducing waste can significantly reduce environmental and social costs. The ASCE report advocates the use of Envision as a standardized tool to promote sustainable pipeline projects.