Chapter 5. Description of Alignment Alternatives

5.1 RECONNAISSANCE REPORT OF THE EXISTING CORRIDOR The existing project road is replete with short and sharp curves, series of S curves and some broken back curves. A maximum of 8 to 10% super elevation has been observed at the hair-pin bends where the existing bituminous surface is in fair condition, whereas for the gravel sections hardly any camber has been observed. There are also a number of sharp curves having inadequate sight distances. The speed of travel on the project corridor ranges from 10 to 25 kmph at most of the sections. Preliminary reconnaissance survey reveals that the project road that passes through villages and settlement areas which are generally located at the hill tops / ridges; therefore steep vertical up and down gradients areas are typical characteristics of the vertical geometry. The travel speeds are restricted generally due to the sharp curves, very steep grades and poor pavement condition.

The following is the list of identified villages along the exist road with details of observed GPS coordinates and an approximate chainage from the start point of the project road:

Table 5-1: Location of Villages Sl no Km Easting Northing Village Name 1 0 459458 2632140 Start of New Alignment at NH 44A Junction near Langte village 2 20 456497 2618391 End of New Alignment near Chungtlang village 3 27 458662 2614580 W Lungdar village 4 36 459399 2609126 Hreichuk village 5 43 456740 2605578 Kanghmun village 6 55 457979 2596647 Bawlte village 7 59 458917 2594640 Darlung village 8 61 459079 2593594 South Sabual village 9 78 462589 2584145 South Khawlek village 10 85 463501 2578918 New Khawlek village 11 92 464850 2573585 Buarpui village A strip chart showing the existing road with the village / settlement locations is projected as follows:

Figure 5-1 5-1

The existing corridor was traversed by the consultants from Km 20 to Km 95 (since from Km 0 to Km 20 there is no existing corridor) and the existing road profile and the existing gradients were mapped by the Consultants. The existing profile of the road is as follows:

Figure 5-2 As inferred from the profile diagram that the proposed new alignment connects the existing road near Chungtlang village at Km 20 at an elevation of 897m after which the exiting road climbs steeply to village of W Lungdar which is located at the highest point where the elevation reaches 1262m. Again there is a marked fall in the existing alignment till the Hreichuk village located at Km 36 and having an elevation of 880m after which the existing road again climbs up to connect Kanghmun village at Km 43 at an elevation of 970m. Again there is a marked fall observed from Km 60 to Km 64 near Darlung and South Sabual village where the elevation drops from 955m to 709m within a distance of 4.5 kilometers. The remaining parts of the corridor shows the similar nature which is marked by sudden rise and fall in gradients.

A summary of the relative elevations along the project corridor as recorded by the hand held GPS observed by the Consultant’s during site reconnaissance survey is given in Appendix 5.1 of Volume 2.

The Consultant also mapped the gradients of existing corridor and the observation is as follows:

Figure 5-3 The existing grade is mapped with respect to a limit line of 5% ruling grade. It is inferred that from Km 20 to Km 30 there is a predominant tendency of steep grades exceeding the ruling value for 5-2

Feasibility Study Report Mizoram State Roads Project –II Project Preparation Consultancy Services for Mizoram State Roads II Project (MSRP II) PPC Package I Phase-I: Junction NH-44A- Chungtlang-Darlung-Buarpui mountainous terrain at most of the mapped sections. Also from Km 55 to Km 68 there is considerable length which shows steep grades. Similarly the same is observed from Km 72 to Km 77 and from Km 86 to the end of the corridor. There are few locations like at Km 36, Km 42 and Km 48, where steep grades are observed but at short stretches.

5.2 FINALIZATION OF THE REALIGNMENT OPTIONS This section primarily focus on the selection of preferred route of the project corridor as mandated in the ToR and the purpose of the Route Selection Alternatives is to present Client (MPWD) and the other stake holders with possible alternate routes for a project road, together with an evaluation of each in technical, environmental and social terms.

5.2.1 Finalization of the start point of the Project Corridor On analysing the various connectivity options from NH 44A junction to the project corridor, the consultants found out the major two alternatives. The alternatives are as follows:

1. Option 1 – NH 44A Junction - Rawpuichhip – Chungtlang: The route starts on NH 44A and traverses nearly 26.8 Km along the existing NH upto the junction to ODR at the village of Rawpuichhip. From the junction the route option traverses along the ODR for a length of 20.4 Km and passes through the villages of Tuahzawl, Rulpuihlim and finally connects the project corridor at the Chungtlang village.

2. Option 2 – NH 44A Junction – Lengte – Chungtlang: The route was to start at the Junction point with NH 44A and follow PMGSY road to the village of Lengte. After traversing a length of 5 Km along the existing road, towards Lengte village, the Consultants assessed that a shortest route can be proposed which will be new alignment in between the take off point before the Lengte village and end of the Chungtlang village connecting the project corridor. The length of the proposed new alignment will be 20 Km.

A key map showing all the alternatives are shown below:

Start Point of Option-2: Consultant came to know by the PWD NH wing that there is a proposal of the realignment of the existing NH 44A and an upgradation (to NH standards) of the existing PMGSY road to Lengte which will serve as a shortest connectivity to the existing and re-aligned NH 44A with Aizawl bypassing Lengpui. The Consultant discussed this fact with the Client and other stake holders and finalised the starting point of the project corridor at a junction to the proposed upgraded PMGSY road.

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A – Junction on NH 44A. B – Existing PMGSY road to Lengte village. (Distance between A to B is 5 Km) C – Joining to project corridor after Chungtlang village. (Distance between B and C is 20 Km and D and C is 20.4 Km) D – Junction of NH 44A and ODR at Rawpuichhip village (Distance between A and D is 26.8 Km)

Figure 5-4: Options for the connection between NH 44A and Chungtlang 5-4

The Consultant reviewed the various options for the best possible alignment that will connect the NH 44A to the Project Corridor at Chungtlang village. The review was preliminarily based on the geometric features of the existing roads and the possible extent to which it can be upgraded to the desired standards.

For the first option, it was observed that the portion of NH 44A (26.8 Km in length) is in fair condition with some of the portions of the section of road is under upgradation by the NH wing. The remaining portion of the NH can be rehabilitated by improvement of sharp curves (about 106 nos of curves having radius less than 30m and some of the hairpin bends) and 35% of the total length having gradients more than 5 to 6%. The remaining length which traverses along the ODR for a length of 20.4 Km will involve major realignments for its upgradation to the desired standards. There are about 268 nos of sharp curves including the hairpin bends having radius less than 30m and 62% of the corridor have gradients more than 5%.

On further investigation of the second option, the Analysis of engineering, social and environmental criteria has been carried out for Option-1 and Option-2 and those are summarized Table 5-8 below:

Table 5-2: Quantitative Comparison of Option-1 and Option-2 Particulars Option-1 Option-2

26.8+20.4=47.2 20 1. Length (km) 26.8 on NH and 20.4 on ODR New Alignment

(i) existing road (km) 47.2 -

(ii) new alignment - 20

2. Land Use (Length in m) - -

(i) Agricultural/Jhum 18600 7080

(ii) Open Forests/ 16940 10470 Vegetation/Bamboo Forests

(iii) Moderately Dense Forests 3000 2300

(iv) Stream/Water Body 160 150

(v) Residential/Commercial 8500 Nil

3. Structures affected 150

4. Affected social amenities - (estimated)

(i) Urinals 7 Nil

(ii) Water points 5 Nil

4. Land to be acquired (ha) 87.2 48 ha

5. Land slide proneness Medium Low to medium

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6. Gradient  5% for 35% length of NH and  5% for 62% length in ODR 7. No of sharp curves 106 in NH section & 268 in ODR

(i) Radius less than 30 m 106 21

(ii) No of hairpin bends 5 Nil

8. CD structures

(i) Culverts 42 35

(ii) Minor Bridges 4 3

(iii) Major Bridges Nil Nil

9 Design Speed (kmph) 20 50

10 Estimated Cost 6,33,80,10,614 2,74,04,80,573

Table 5-3: Qualitative Analysis of Option-1 and Option-2 SL. NO. DESCRIPTION OPTION – I OPTION -II 1 Land availability ◊ Θ

2 Land use suitability ◊ Θ

3 Residential / commercial buildings affected ◊

4 Ponds/ water bodies Affected Θ

5 Religious Structures Affected ◊

6 Gradient suitability ◊

7 Land slide proneness ◊ Θ

8 Achievable speed of travel ◊

9 Expected Travel time ◊

10 Emission savings ◊

Legend:

◊ Less Desirable Θ Desirable Most Desirable

It can be noted form the above tables that Option-II on is suitable based on the quantitative and qualitative parameters, hence recommended for the project.

Consultant explored the various alternatives to finalize option-2 (the proposed new alignment from the start point to the connecting point at existing road at outskirt of Chungtlang village. Those are given in brief in subsequent paragraph.

The key plan showing the proposal for the realignment of the National Highway and the upgradation of the existing PMGSY and the proposed starting point of the project corridor road is shown in Figure 5-5.

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Figure 5-5: Key plan for the starting point On further analysis of the two options, and after various stages of discussions with Client and PWD NH-Division, Aizawl, it was found that the option-2 is the best possible option for the following advantages:

 The length of the alignment is the least which will induce the minimum future pollution load and will affect minimum wear and tear of vehicles thereby reducing the vehicular operating costs.

 The entire alignment was kept within a permissible grade of 5% to 6% with the starting point at an elevation of 320m and terminating at 868m. The curves also kept so as to attain a minimum speed of 50~40 kmph.

 There will be a minimum social impact as the corridor don’t intercept any villages.

 The construction cost will also will be minimum due to the shorter length.

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5.2.2 New alignment from starting point to Chungtlang village From the starting point of the corridor i. e. from Km 0 to Km 20 there is no existing road so the Consultant has proposed a completely new alignment which starts before the Lengte village and terminates at outskirt of Chungtlang village.

The Consultant studied two more options (option 3 and option 4) from the topographic sheets of Survey of India and simultaneously verified the same from the satellite imageries available in public domain. After a series of discussions with client and other stake holders like the village VCPS etc. the Consultant analyzed following alternatives to finalize option-2:

Figure 5-6: Option-2, Option-3 and Option-4 on Satellite Image

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To select best suitable alternatives, Consultant has collected information for Option-2, Option-3 and Option-4. The merits and demerits of the all three options are presented below in Table 5-10:

Table 5-4: Merits and Demerits of Options for new alignment Option 2 Option 3 Option 4 Length 19.7 Km 23.2 Km 20.3 Km Geometric features Smooth curves with Smooth curves with 3 nos. of hairpin bends are gradient around 5 to 6% gradient more than 8% at required with gradients few locations but remaining beyond 6% for most of the locations, the gradient is profile. within 6% Geological features Secondary information and Secondary information and Secondary information and preliminary ground preliminary ground preliminary ground reconnaissance reveals the reconnaissance reveals the reconnaissance reveals the alignment is on stable hills alignment is on unstable alignment is on stable hills and rock slopes. rock plates which needs and rock slopes. costly geotechnical restorations. Cross drainage structures Preliminary study reveals 3 Preliminary study reveals 4 Preliminary study reveals 3 minor bridges and 35 cross minor bridges and 25 cross minor bridges and 48 cross drainage structures drainage structures drainage structures Based on the above analysis, the alignment ‘Option 2’ is recommended as a best suitable one which is shown in Figure 5-7 below:

Figure 5-7: Recommended New alignment from 0 Km to 20 Km After the desk study, a walk through ground reconnaissance is made by the Consultant’s team through the proposed new alignment (option-2) to assess the tentative location of the cross drainage structures and hydrological issues, nature of soil and material and biodiversity along the corridor. The finding of the desk study resembled with the ground condition.

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5.2.3 Re-alignment for West Lungdar The Consultant investigated the existing road from outskit of Chungtlang village,where the proposed new alignment terminates and travelling through the next village called West Lungdar. Mapping the profile and gradients shows that desirable gradient is not achievable if existing road is improved. The magnitude of the grades plotted against the chainage is presented in Figure 5-8 below:

Figure 5-8: Grades for the existing road Km 20 to km 28 has been divided into 16 units (each unti 500 m length). Analysis of the Figure 5- 8 shows that 11 units out of 16 exceed desirable gradient 5%, i. e major portion of the existing road is characterized by steep gradients and hence the Consultant proposed a re-alignment from Km 20 to Km 29.

Two options (excluding existing road, option-1) have been considered for realignment between the said chainage:

 Option-2 on the eastern side of West Lungdar village and  Option-3 on the western side of West Lungdar village. The contour study on the slopes of the hills of West Lungdar village on eastern side and western side reveals that the eastern side of the hill has a gentle slope whereas the western section had a very steep slope. Desk study followed by ground truthing confirms the same. Villagers informed us that rock sheets have inclination downwards on eastern side. It is also confirmed by site investigation. The villagers are doubtful that if realignment is constructed on eastern side of village, entire village is likely to slide downward following inclination of the rock sheets. Geological investigations further inferred that though the eastern side on the hill has a gentler slope but the rock plates are not stable one and are susceptible to slippages and sliding whereas on the western side the rock faces is more stable and compact in nature. It was also deduced that construction on the eastern side will warrant huge quantum of rock stabilization measures. On the other hand, though construction of realignment on the western side may be hazardous but it will be more stable. All the options are superimposed on the satellite image and presented in Figure 5-9 below:

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Figure 5-9: Options for West Lungdar Realignment Analysis of the all the options have been carried out of based on engineering, social and environmental criteria and summarized on Table 5-11 below:

Table 5-5: Merits and Demerits of Options for West Lungdar Realignment Option-1 Option-2 Option-3 Particulars (Existing Road) (Eastern Side) (Western Side)

1. Length (km) 8.6 7.5 5.3

(i) existing road (km) 8.6 -

(ii) new alignment (km) 7.5 5.3

2. Land Use (Length in m) - -

(i) Agricultural/Jhum 3000 3500 1500

(ii) Open Forests/ 3970 4170 2700 Vegetation/Bamboo Forests

(iii) Moderately Dense Forests 1260 -

(iv) Stream/Water Body 30 40 30

(v) Residential/Commercial 1200 - -

3. Structures affected (no) 46 Nil Nil

4. Affected social amenities - - - (estimated)

(i) Urinals 1 - -

(ii) Water tank 1 - -

(iii) Cemetery 2 - -

4. Land to be acquired (ha) 16.1 18.0 12.7

5. Land slide proneness Low Medium Medium to high

6. Gradient > 7% 5% to 6% 5% to 6%

7. No of sharp curves

(i) Radius less than 30 m Very sharp curves Smooth curves Smooth curves

(ii) No of hairpin bends 5 Nil nil

8. CD structures (No)

(i) Culverts 16 19 24

(ii) Minor Bridges 2 1 1

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(iii) Major Bridges Nil Nil Nil

unstable and prone to stable 9. Geological features Stable as on the ridge slippages

10 Design Speed (kmph) 15 35 40

11 Estimated Cost 1,20,75,97,094 1,04,28,19,570 77,33,58,751.10

Based on the above facts, the option for the rehabilitation and upgradation of the existing road has been ruled out. Regarding the suitability of the alignment in the eastern or the western side, the Consultant has carried out detailed geotechnical investigations for option-2 and option-3 and analysis of the samples is in progress. Decision can be finalized only after review of the analysis report. Consultant will select best suitable alternative and incorporate Draft Detailed Project Report.

5.6.1.1 Strip plan of the Final Alignment Based on the extensive studies which includes desk studies of topographic maps and aerial satellite images and other secondary information like land use maps, earthquake intensity maps, land slide maps, forest maps, followed by a walk through ground reconnaissance, and then after a series of discussions with the Client, other stake holders and organizing village consultations the Consultant concluded the alignment for the said corridor. The strip plan of the final alignment is projected as below:

Length of Final Length of Existing length of New Sl. No. From To Description Road project Alignment Bypassed corridor (Km) (Km) (Km) Package 1 Phase 1 Start of New End of New 1 Alignment near Alignment near New alignment 20 20 20 Langte Chungtlang End of New End of W 2 Alignment near New alignment 7.5 8.6 7.5 Lungdar Chungtlang

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