Analyzing the Alignments of Roads by Giving Weightages to Various Factors - a Case Study

There is an increasing demand of Infrastructure roads due to increase in road traffic and related issues in safety. Roads are the dominant mode of transportation in India. Roads carry almost 85 percent of the country’s passenger traffic and more than 62 percent of its freight traffic Due to improvement in transportation network, reduction in transportation costs, such as reduction in travel time, decrease in vehicle operations cost, increased safety and reduction in the level of air and noise pollution. In addition to reduction is transportation cost, it also increases comfort to passenger and enhancing land value. Widening of road is mostly the case followed for the increasing demand. However, nowadays, for catering the needs of increasing traffic demand, Greenfield alignment is also as an option. Hence, there are advantages and disadvantages in both the alignments. This study involves for comparing and analyzing a NH 160A highway section between Ghoti to Trimbakeshwar for a length of 14.3 km. This paper compares the pros and cons of both alignments, costing of both the alignments, Geometry of both alignments; problems/issues like encroachment, forest area, Utilities in both alignments. In this study, the optimal alignment has been arrived by bringing all the issues to a common platform with a grading system. Further, different scenarios considered based on the requirement of a Client by doing Sensitivity analysis for various cases.


Introduction
Before starting of any project, road alignment needs to be determined this are an optimal alignment and a basic requirement for implementation of a Highway project. There are two approaches in planning stage. Either widening of existing roads are done or a new alignment is planned which is a Greenfield alignment. Hence, it is necessary to consider both the alternatives in designing stage based on the benefit it will render to the highway user as well as the agency constructing it. The benefits can be in term of savings in travel-time and construction cost, safety improvements, and reduction in environmental impact. The aim of this research is to develop a grading system to compare all the factors on a common platform and hence design the optimized highway alignment between two given points. Hence, this study needs to be authentic, accurate and thorough as investment option depends on this basis.

AR T IC LE IN F O A BS T RA C T
There is an increasing demand of Infrastructure roads due to increase in road traffic and related issues in safety. Roads are the dominant mode of transportation in India. Roads carry almost 85 percent of the country's passenger traffic and more than 62 percent of its freight traffic Due to improvement in transportation network, reduction in transportation costs, such as reduction in travel time, decrease in vehicle operations cost, increased safety and reduction in the level of air and noise pollution. In addition to reduction is transportation cost, it also increases comfort to passenger and enhancing land value. Widening of road is mostly the case followed for the increasing demand. However, nowadays, for catering the needs of increasing traffic demand, Greenfield alignment is also as an option. Hence, there are advantages and disadvantages in both the alignments. This study involves for comparing and analyzing a NH 160A highway section between Ghoti to Trimbakeshwar for a length of 14.3 km. This paper compares the pros and cons of both alignments, costing of both the alignments, Geometry of both alignments; problems/issues like encroachment, forest area, Utilities in both alignments. In this study, the optimal alignment has been arrived by bringing all the issues to a common platform with a grading system. Further, different scenarios considered based on the requirement of a Client by doing Sensitivity analysis for various cases.

Advantages and Disadvantages
Factors considered for advantages and dis-advantages are as follows: 1) Alignment-Green field alignment will follow the curves matching with IRC standards. 2) Land acquisition-People staying in built up areas object to give the land and hence delay in land acquisitions in Brownfield project. 3) Built-up areas-Interference from local public and land acquisition delays in the project 4) Encroachments-Public anger and Law and order situation while removing the encroachments delays the widening projects. 5) Utility shifting-Many utilities adjacent to existing roads add to cost of shifting the same and delays the project of widening. 6) Speed of Construction-Above factors reduces the speed of widening project. 7) Safety during Construction-Existing moving traffic in Brownfield alignment project is prime importance. Restrictions from traffic Police for getting permissions to work in phased manner. 8) Accidents-Non-standard curves in present existing alignment might result in extra injuries due to accidents in Brownfield. 9) Environment-Old trees adjacent to existing roads needs cutting in case of brownfield alignments. Tree cutting permission consumes a lot of time. Substandard curves in current alignment make heavy trucks to transport in lower gears, which end up in smoke pollutants and noise pollutants. 10) Toll fees-If Brownfield road is toll road; people do not have the choice to take another road. 11) Forest areas-The alignment of road in Forest areas is by-passed in Greenfield alignments as it takes lot of time for work permission from Forest Department. 12) Construction cost-Greenfield alignment length might be generally lesser in length; it could have trouble in terrains and subsequently may be costly. 13) Land acquisition cost-Land cost near existing roads will be more costly then land away from Built up area. 14) Construction issues-Differential settlements issues will be there in Brownfield project. 15) Geometric design-Green field alignments can meet speed requirements as per design throughout the project length as vertical and horizontal alignment is as per the specifications. 16) Time value-Traffic jams due to sub-standard curves can be a concern for achieving time value in Brownfield alignments.

Project Features
Project features for both the alignments are as shown in Table I.

Traffic details for both alignments
The existing traffic detail from traffic survey was used for deciding the lane configuration of the project road [2] as shown in Table II. A. Cross-Section considered for both alignments:   2) Cost Computation for Greenfield alignment as per Figure 3 as shown in Table IV

Comparison considering environmental and social factors
In Greenfield alignment, tree cutting involved is very less as compared to Brownfield alignment. Further, the Brownfield alignment is passing through a forest stretch for a length of about 1.35 km length.

Sensitivity calculations
To compare the Green field and Brownfield alignment, a grading system is adopted in this paper to bring it to common platform all the factors like Geometry, Costing and other issues/hurdles like Built up areas, Forest areas etc.

1) Geometry of Road
In this, sub-factors considered are like number of curves and lengths, speed achieved, time of travel for the proposed stretch and length of road in both cases i.e. Brownfield and Greenfield alignments.

Curves
In Brownfield alignment, the numbers of locations of curves are 19 with a cumulative length of 1673m. Whereas, in Greenfield alignment the number of curve locations are eight with a cumulative length of 1176m. In the ideal case, the curves shall be zero. The ideal case of zero curves is absent in both the alignments. The percentage achieved in brownfield alignment is =100-(1673/14300*100) i.e. 88.3%. The percentage achieved in Greenfield alignment is =100-(1176/11934*100) i.e. 90.15%. Hence grading of 8.8 and 9 are for Brownfield alignment and Greenfield alignment respectively.

3) Other issues
The sub-factors under this are Built-up area, Speed of Construction and Forest area. In this case as per the practical experience, the construction will delay by one year due to forest clearances for 1.36 km length and Built-up area of 0.2 Km length. On pro-rata basis, the delay due to forest area and built -up area will be 315 days and 45 days. However, in ideal case, the time required for completing

Sensitivity analysis
The grading system adopted for arriving at the optimal alignment as observed in the above Calculations. There can be different weightages given to above factors. We have to do sensitivity analysis by giving different weightages to different factors. Some Clients may give more weightage to Costing and some may give to Geometry. Here we will do analysis by giving no weightage, by giving 25:50:25 weightages to Geometry, Costing and other factors in alignment. Similarly, the analysis in the form 5:90:5 and 0:100:0 done as follows. Both the alignments are checked to verify which alignment is optimal.

Conclusion
We observed that the average speed achieved in Greenfield alignment is 84 kmph in comparison to 64 kmph in Brownfield alignment, which leads to saving of time of 5 minutes for considered length of 14.3 km. We observed that the total cost of Greenfield alignment including construction cost, escalation due to delays, land cost, Utility Shifting cost is Rs 147.47 Cr in comparison with Brownfield alignment cost of Rs 149.64 cr. Greenfield has less pollution due to smooth horizontal curves as per specifications and less tree cutting is involved. Brownfield alignment passes through 1.35km Forest area affecting to some extent the natural environment. Hence, Greenfield alignment has less impact on Environment compared to Brownfield alignment. Brownfield alignment passes through 0.2 km Built up area and Greenfield alignment does not pass through Built-up area. Hence, in case of Greenfield alignment there is nil effect on rehabilitation and saving in project time as compared to Brownfield alignment. From the above study, we observed that Greenfield alignment has more advantages considering geometry, time cost, environment and Social criteria. From the Sensitivity analysis, the weightage of 25 percent-50percent-25percent on Geometry, Costing, and hurdles gives a mark 6.38 to Brownfield alignment and 9.32 to Greenfield alignment. Further, considering variation in weightages to all factors, Greenfield alignment gets higher grading in all cases. From the above, it is concluded that, Greenfield alignment has more advantages as compared to Brownfield alignment. Hence, optimal alignment for the construction of two-lane section of Ghoti to Trimbakeshwar is Greenfield alignment and is proposed for the development of the project road.