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National Highway 66 (India)
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National Highway 66
Map
Map of the National Highway in red
Route information
Part of AH20
Length1,640 km (1,020 mi)
Major junctions
North end NH 48 in Panvel, MH
Major intersections
South end NH 44 in Kanyakumari, TN
Location
CountryIndia
States
Highway system
← NH 65→ NH 166

National Highway 66, commonly referred to as NH 66 (erstwhile NH-17 and a part of NH-47),[1] is a mostly 4 lane 1640 km (1020 miles) long busy National Highway that runs roughly north–south along the western coast of India, parallel to the Western Ghats. It connects Panvel, a city east of Mumbai (Bombay) to Cape Comorin (Kanyakumari) via Mangaluru, passing through the states of Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu.

The highway is[when?] undergoing a major overhaul in Karnataka, where the state government has accepted the NHAI's request of international standard, 60-metre-wide national highway with grade separators.[2] The complete stretch from the Goa border (near Karawara) to the Kerala border (near Talapady) is being widened to four lanes, with space to accommodate future expansion to six lanes.[3] There were protests from the people, who will lose lands, for a narrower stretch. But the Karnataka government has not heeded to the protests.

Land acquisition and tendering process for six lane national highway has been finished in Kerala. New bypass works have already been kick-started. Owing to higher density of population and high land value, national highway will be 45 meter width, 6 lane, in Kerala. Goa also will have a similar alignment. Karnataka and Maharashtra sections will have 60-meter width. The Maharashtra section will be converted into a flexible pavement (asphalt) road with four lanes.[4][5][6]

The Ministry of Road Transport & Highways, Government of India has proposed a greenfield (i.e., new and parallel) access controlled expressway corridor connecting the port cities of Mangaluru-Karawara-Panaji as part of the Indian National Expressway Network.[7] This expressway will be parallel to NH-66 and will be mainly located in coastal Karnataka. It is expected to be a 6/8 lane access-controlled 3D right-of-way designed expressway.

Route description

[edit]

It starts at Panvel, at the junction of National Highway 48 (old NH4), and ends at Kanyakumari. NH-66 mainly traverses through the west coast of India, sometimes touching the shores of the Arabian Sea. The NH-66 touches the Arabian Sea at Maravanthe in Karnataka, Thalassery, and Alappuzha in Kerala. It passes through the Indian states of Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu. The National Highway 66 (previously numbered NH-17) connects cities, towns, and major villages of different states as follows:

Maharashtra

Panvel, Pen, Mangaon, Mahad, Poladpur, Khed, Chiplun, Sangameshwar, Ratnagiri, Lanja, Rajapur, Kanakvali, Kudal, Sawantwadi.

Goa

Panaji, Margao.

Karnataka

Karawara, Ankola, Kumta, Honnavara, Manki, Murudeshwara, Bhatkala, Shirooru, Bainduru, Uppunda, Kirimanjeshwara, Navunda, Maravanthe, Hemmadi, Talluru, Kundapura, Koteshwara, Kota, Saligrama, Brahmavara, Udupi, Kapu, Padubidri, Mulki, Surathkal, Mangaluru, Thokottu, Ullal, Kotekar, Talapady.

Kerala

Uppala, Kasaragod, Kanhangad, Payyannur Pariyaram, Taliparamba, Dharmashala, Kannur, Dharmadam, Thalassery, Mahe, Vatakara, Payyoli, Koyilandi, Kozhikode, Ramanattukara, Tenhipalam, Kottakkal, Puthanathani, Valanchery, Kuttippuram, Thavanur, Ponnani, Chavakkad, Vadanappally, Kodungallur, Moothakunnam, North Paravur, Koonammavu, Varapuzha, Cheranallur, Edappally, Kochi, Aroor, Cherthala, Alappuzha, Ambalapuzha, Haripad, Kayamkulam, Karunagappally, Chavara, Neendakara, Kollam, Mevaram, Kottiyam, Chathannoor, Kallambalam, Attingal, Kazhakkoottam, Thiruvananthapuram, Balaramapuram, Neyyattinkara, Parassala.

Tamil Nadu

Marthandam, Nagercoil and Kanyakumari.

Major intersections

[edit]
State District Location km mi Destinations Notes
Maharashtra Raigad Panvel 0 0 NH 48 to New Delhi Northern end of the highway.
Vadhkal 36 22 NH 166A to Alibag
Ratnagiri Chiplun 216 134 NH 166E to Bijapur
Hatkhamba 289 180 NH 166 to Ratnagiri, Solapur
Goa North Goa Panaji 513 319 NH 748 to Belgaum
South Goa Cortalim 529 329 NH 366 to Vasco da Gama Route to Goa Dabolim Airport
Verna 567 352 NH 566 to Vasco da Gama Route to Goa Dabolim Airport
Karnataka Uttara Kannada Ankola 667 414 NH 52 to Sangrur Terminus of NH 52
Kumta 692 430 NH 766E to Haveri Route to Devimane Ghat, Sirsi. Terminus of NH766E
Honnavar 713 443 NH 69 to Chittoor Terminus of NH 69
Udupi Udupi 841 523 NH 169A to Thirthahalli
Dakshina Kannada Mangalore 900 560 NH 73 to Tumakuru

NH 169 to Shivamogga

Terminus of NH 73
Kerala Kannur Thalassery 1,076 669 SH 30 to Mysore Route to Mysore via NH 275 passing through Coorg
Kozhikode Malaparamba 1,122 697 NH 766 to Kollegal
Ramanattukara 1,156 718 NH 966 to Palakkad
Ernakulam Cheranallur 1,340 830 NH 966A to ICTT Kochi
Edapally 1,346 836 NH 544 to Salem
Kundannoor 1,356 843 NH 85 to Thondi
NH 966B to Cochin Port 		Terminus of NH 85

Southern Naval Command headquarters - INS Vendruruthy

Kollam Chavara 1,473 915 NH 183A to Vandiperiyar Terminus of NH 183A
Kadavoor 1,503 934 NH 183 to Theni/Dindigul
Kallumthazham 1,530 950 NH 744 to Tirumangalam
Tamil Nadu Kanyakumari Nagercoil 1,624 1,009 NH 944 to Kavalkinaru
Kanyakumari 1,640 1,020 NH 44 Southern end of the highway.
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

Road condition

[edit]

The NHAI has received the approval to upgrade the complete stretch of highway, from start to end, to a four-lane highway, which will be 60 m (200 ft) and grade separated. Out of four states through which the highway goes, Karnataka and Maharashtra have received approval from the centre for the 60 m (200 ft) wide highway. Kerala and Goa have requested a narrower width of 45 m (148 ft), and there are protests against the highway being widened in these states.[8][9] The four-laning of NH-66 (Mumbai-Kanyakumari) has been completed until Thalapadi in the Karnataka-Kerala border and only its stretch in Kerala is pending.[10] In the beginning of 2017, Kerala government has announced the six laning of NH 66 in the state as a major agenda and said to be completed in three years. But the high value of land will make it hard for compensation, and the ruling party's influence is controversial in relation to similar acquisitions like GAIL pipeline.[11][12] Now the process is going fast in spite of protests from various highway action forum groups,[13] especially because it connects Kerala's capital Thiruvananthapuram to Kochi and of tourism importance.[14] NH 66 has one of the highest vehicle densities in the state compared to sections of the highway in other states, so its development is vital for the overall development of the state, also the HAM model to be followed in widening will be instrumental in collecting the funds for the development. NHAI has been infamous for their heavy and long tenure of toll collection in the state.[15] Till now 961 km (597 mi) stretch out of 1,608 km (999 mi) long National Highway 66 (NH 66) have been made into four-lane highway. Karnataka and Maharashtra are widening to six-lane & 529 km (329 mi) stretch out of 1,608 km (999 mi) long National Highway 66 (NH 66) have been made into six-lane highway. Tunnels will be constructed in the stretches where the road goes through the forest or ghat section. As the forest department does not allow land acquisition for road widening purposes, tunnels which can accommodate four-lane expressways are proposed for such stretches of the road in NH-66.[16] One such proposal is the Maharashtra government's proposal of 1.4 kilometre tunnel at the Karnala bird sanctuary.

Kollam Bypass near Kadavoor

Currently, the road is comparatively narrow and without dividers for the most part. The lack of dividers has led to an increased incidence of head-on collisions between vehicles. At some places, signboards indicating left or right turns, speed-breakers, etc. are either damaged or missing. In addition to its narrow span, there are no guard railings along the sides of the highway. The sides of the road are at times at a lower level than the road.[17] Due to heavy human settlement around the highway and narrow span, the average speed on this highway is far lesser than what can be attained on comparatively better highways such as NH3, NH4 or NH8. One can find carcasses of animals on the road, indicating the risk of inattentive animals coming into the road. Two-wheel vehicles must take a special note of this. The road surface is uneven at certain stretches, not just in rainy seasons, but even at other times.

National Highway 66

At certain places in Karnataka, the surface is so badly damaged that the iron rods underneath are exposed. Presently, the work on widening this highway has been undertaken at certain stretches. Due to narrow span and lack of dividers, there are no separate lanes for oncoming traffic, driving and passing (over-taking). As a result, over-taking is quite rampant. At times, motorists attempt over-taking even on curves where the oncoming traffic cannot be seen. Other motorists are advised to be on the lookout for such oncoming vehicles.

On 19 March 2013 a bus carrying over 50 persons fell off a bridge close to a river in the Khed area of Ratnagiri district. 37 people were killed in the incident.

The highway in the state of Karnataka is being upgraded to a 60-metre-wide grade separated highway, in which vehicles can travel at a speed of 100 km per hour. It is a major overhaul, in which certain bridges are being constructed as six-lane bridges for the smooth movement of traffic. The widening work is going on in the complete stretch from the Goa border to the Kerala border. The stretch between Suratkal (NITK) to Kankanady cross (Mahavir Circle) has been already converted to four lanes.[18] The four-lane stretch between Surathkal and Kundapura has been completed.[19]

The Maximum permissible speed for this road is 100 km/h on 6-lane national highways in kerala.

Connectivity

[edit]

Prior to the building of National Highway 66 (NH 66), then known as National Highway 17 (NH17), in the 1960s and 1970s, ships and steamers running between Mumbai and Mangaluru calling at different ports were the only means of transport along the west coast of India adjoining the Arabian Sea. These ship services were abandoned later. The NH 66 connects the interior parts of the coastal regions with the rest of the country. The NH 66 connects the major sea ports of West India;JNPT at Nhava Sheva, Vizhinjam International Seaport at Trivandrum, Mormugao (MPT), New Mangalore (NMPA), International Container Transshipment Terminal at Kochi, Kollam Port, Ratnagiri Port and Beypore Port.

Hence this National Highway 66 allows for the movement of goods by trucks (lorries) from the hinterland to the major sea ports of India. Trade and commerce in the region have increased due to the expansion of markets for agricultural products and seafood produced in the region connected by this highway. The formation of NH 66 has led to the development of tourism in the region connected by this highway. Goa state is a classic example of this development. Many industries have been set up along National Highway 66, taking advantage of connectivity and proximity to ports on the Arabian Sea. The highway was the only source of connection between areas in the coastal districts, until the Konkan Railway was opened in 1998, between Mumbai and Mangaluru.

One can still find old number NH-17 written on boards of shops and other establishments along NH-66 highway even in the year 2017.

Collapses

[edit]

On 19 May 2025 at 2:30 pm IST, a section of National Highway 66 caved in near Kooriyad, Malappuram district, Kerala, at around 2:30 pm on May 2025.[20] The collapse, including a retaining wall, fell onto the service road built over the filled paddy field, causing the nearby paddy field to split and form a small hill. The collapse occurred on a road under construction by the KNRCL company[21] in the Ramanattukara-Valanchery reach of the new 6-lane National Highway. Four cars on the service road were damaged in the collapse. Seven passengers travelling in the car were injured.[22] Three cars were involved in the accident, and seven were injured. The collapse significantly delayed construction on NH66.[23] No casualties occurred.[24]

The Ministry of Road Transport and Highways has issued an order to reconstruct the road and investigate the accident. The central government has debarred the KNRC company that was carrying out the construction.[25] Member of Parliament (Malappuram) E. T. Mohammed Basheer discussed the accident details with Union Road Transport Minister Nitin Gadkari,[26] and Nitin issued an order for investigation and banned the KNRC company that was carrying out the construction work.[27][22] Kerala Chief Minister and Kerala Public Works Department have also ordered an investigation into the accident.[28]

Union Road Transport Minister Nitin Gadkari agreed to carry out a full investigation into the collapse. Member of Parliament E. T. Mohammed Basheer met Union Minister Nitin Gadkari immediately after the incident and said that the Union Minister had assured that appropriate action would be taken against the National Highways Authority of India (NHAI) officials if they were found responsible for the lapses. He also said that Gadkari had said that steps would be taken to enforce the bank guarantee given by the contractor and blacklist the construction company.[26] Congress President Sunny Joseph asked the Pinarayi Vijayan government to determine the responsibilities for the deteriorating National Highway 66.[29]

Protests took place in Kooriyad, and Indian Youth Congress workers held a protest march to the KNRCL office. On 20 May, the Muslim Youth League held a protest march at Kuriyad.[30][31]

Another similar incident occurred at Mylakkadu in Kollam, Kerala, on December 5, 2026.[32]

Major cities and places on the highway

[edit]

Maharashtra state

[edit]
District Places or Cities
Mumbai Suburban Panvel
Raigad Pen, Nagothane, Kolad, Indapur, Raigad, Mangaon, Mahad, Poladpur
Ratnagiri Khed, Chiplun, Savarde, Sangameshwar, Lanja, Rajapur
Sindhudurg Kankavli, Kudal, Sawantwadi, Sindhudurg, Banda

Goa state

[edit]
NH-66 in Goa
Pernem Mapusa Panjim
Margao Cuncolim Canacona

Karnataka state

[edit]

Uttara Kannada District

[edit]
Karwar Ankola Kumta
Honnavar Murudeshwar Bhatkal

Udupi district

[edit]
Baindooru Uppunda Maravanthe Kundapura Kota
Saligrama Brahmavara Udupi Kapu Padubidre

Dakshina Kannada

[edit]
Mulki Suratkal Mangaluru Ullal

Kerala state

[edit]
District Places or Cities
Kasaragod Manjeshwar, Uppala, Kasaragod, Bekal, Kanhangad, Nileshwar, Cheruvathur, Payyanur
Kannur Taliparamba, Kalliasseri, Kannur, Muzhappilangad, Dharmadom Thalassery, Kodiyeri
Kozhikode Vatakara, Iringal, Payyoli, Moodadi, Koyilandy, Kappad, Vengalam, Elathur, Kozhikode, Pantheeramkavu, Ramanattukara
Malappuram Tirurangadi, Kottakal, Puthanathani, Valanchery, Kuttippuram, Ponnani
Thrissur Edakkazhiyur, Guruvayur, Chavakkad, Chettuva, Vadanappally, Thalikulam, Triprayar, Valapad, Kodungallur,
Ernakulam North Paravur, Koonammavu, Cheranallur, Kochi, Edappally, Palarivattom Vyttila, Maradu
Alappuzha Aroor, Thuravoor, Cherthala, Alappuzha, Punnapra, Vandanam, Ambalapuzha, Karuvatta, Haripad, Kayamkulam
Kollam Oachira, Karunagappalli, Chavara, Neendakara, Kollam, Thrikkadavoor, Mevaram, Kottiyam, Chathannoor, Parippally
Thiruvananthapuram Alamcode, Attingal, Kazhakkoottam, Kochuveli, Thiruvananthapuram, Vizhinjam, Parassala
  • Bold indicates cities

Puducherry (union territory)

[edit]
Mahé

Tamil Nadu state

[edit]
Marthandam Thuckalay
Nagercoil Kanyakumari

Toll Plazas

[edit]

Under construction Toll Plazas in Kerala

[edit]
District[33] Location
Kasaragod district Pulloor Periya
Kannur district Kalliassery
Kozhikode district Mampuzha
Malappuram district Vettichira
Thrissur district Nattika
Alappuzha district Kommadi
Kollam district Ochira
Kollam district Kalluvathukkal
Thiruvananthapuram district Thiruvallam

Major city/town bypass roads on the highway

[edit]
Bypass District State
Thiruvananthapuram Bypass Thiruvananthapuram Keralam
Attingal Bypass Thiruvananthapuram Keralam
Kollam Bypass[34] Kollam Keralam
Alappuzha Bypass Alappuzha Keralam
Kochi Bypass Ernakulam Keralam
Kodungallur Bypass Thrissur Keralam
Vadanappally Bypass Thrissur Keralam
Ponnani Bypass Malappuram Keralam
Valanchery Bypass Malappuram Keralam
Puthanathani Bypass[35] Malappuram Keralam
Kottakkal Bypass Malappuram Keralam
Kozhikode Bypass Kozhikode Keralam
Koyilandy Bypass Kozhikode Keralam
Vadakara Bypass Kozhikode Keralam
Thalassery-Mahe Bypass Kannur Keralam
Taliparamba Bypass Kannur Keralam
Payyannur Bypass Kannur Keralam
Sawantwadi Bypass Sindhudurg Maharashtra
Margao Western Bypass South Goa Goa

Lifestyle along NH 66

[edit]

NH 66 passes through hills, forests, rivers, rivulets, and streams, generally flowing westwards towards the Arabian Sea. Most of the region has typical scenes like coconut trees dotted all along with paddy fields and arecanut gardens. The road is uneven, and bumps, curves, steep rises and narrow paths in between hillocks are found all over this highway. As this region experiences heavy rainfall, potholes are abundant.

Although the languages spoken vary along the highway, the food of the people along the NH 66 has some common ingredients like coconut, chili, pepper, coconut oil, and fish. The region has a higher literacy rate than other regions of India.[36] The building of National Highway 66 has led to rapid development of the towns and cities along the highway.

Parallel access controlled expressway

[edit]

This highway is expected to lose importance in coastal Karnataka as the Ministry of Road Transport & Highways, Government of India has proposed a greenfield (i.e., new and parallel) access controlled expressway corridor connecting the port cities of Mangaluru, Karwar, and Panaji.[7][37] This highway-expressway combination can be compared to the Mumbai-Pune Highway-Expressway combination.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

National Highway 66 (India)

View on Grokipedia
from Grokipedia
National Highway 66 (NH 66) is a coastal national highway in spanning approximately 1,640 kilometres from in to in , traversing the states of , , , and along the shoreline parallel to the . Previously designated as National Highway 17, NH 66 was renumbered as part of India's national highway rationalization efforts and now primarily consists of four to six lanes, facilitating high-volume traffic including freight to key ports such as , , Mangalore, and . The highway plays a critical role in regional economic connectivity, supporting trade, tourism, and logistics by linking industrial hubs, fishing communities, and tourist destinations, though its development has involved extensive widening projects under the (NHAI). Significant upgrades, including six-laning in and sections, aim to enhance capacity and reduce congestion, with innovations like the use of steel slag for sustainable road construction implemented on portions between and . However, the highway has faced challenges, including embankment collapses in attributed to substandard engineering and soil instability, as well as environmental and livelihood disruptions from expansions in coastal . These issues underscore ongoing needs for improved construction standards and oversight in vulnerable terrains.

History

Origins as Coastal Highway

The route comprising National Highway 66 was initially developed as India's primary coastal highway under the designation of National Highway 17 (NH17) in the pre-2010 numbering system, extending approximately 1,045 km from near southward to Edapally near , parallel to the and . This alignment connected key coastal settlements, ports, and economic hubs across , , , and northern , facilitating maritime trade, passenger movement, and regional integration since the post-independence era. The southern segment from Edapally to , spanning about 530 km through and , operated as part of NH47, completing the continuous coastal linkage to India's southern tip. Established under the framework of the National Highways Act of 1956, which empowered the to declare and maintain inter-state highways of national importance, NH17's coastal orientation prioritized access to fishing communities, beach economies, and hinterland agriculture while avoiding the rugged terrain of the Ghats. Early construction emphasized basic two-lane carriageways with periodic upgrades for bridges over rivers like the , Zuari, and Mandovi, reflecting incremental investments during the and to support Nehru-era goals of national connectivity. By the , the highway had become a bustling for and Malabar region transport, though prone to seasonal disruptions from monsoons and landslides due to its proximity to the sea and hills. This coastal highway's foundational role underscored its strategic value for defense and commerce, linking naval bases at and with export-oriented industries, yet it remained largely underdeveloped compared to inland radials until pre-2010 phases of the National Highway Development Project initiated selective widening and resurfacing. Official records indicate that by 2000, over 80% of NH17's length was two-laned with unmetalled shoulders, handling daily traffic volumes exceeding 10,000 vehicles in urban stretches like Mumbai-Goa.

Renumbering and Pre-2010 Developments

Prior to the renumbering, the alignment of what became National Highway 66 operated primarily as National Highway 17 (NH 17) from in southward through , , and to Edapally near , covering approximately 1,045 km, with the southern extension from Edapally to handled as part of National Highway 47 (NH 47). This bifurcation reflected the pre-2010 numbering's lack of continuity for the full coastal corridor, limiting unified development planning despite its role in linking major ports like JNPT, , and . Under the (NHDP), initiated in 2000, select stretches of NH 17 received upgrades, including widening to four lanes in phases; for instance, projects in and advanced intermittently, but much of the route remained two-lane with frequent bottlenecks, as evidenced by ongoing works near Mangalore reported as nearing completion by late 2010. In , widening proposals for NH 17 sections dated back to the 1980s, yet faced chronic delays from land acquisition issues and local protests, with agitation intensifying by 2010 over environmental and displacement concerns. The renumbering stemmed from a February 2010 government directive to rationalize highway designations for greater scientific consistency, officially notified by the Ministry of Road Transport and Highways on April 28, 2010, assigning even numbers to north-south routes that increase progressively southward from the national borders. This reform consolidated NH 17, portions of NH 47 from Edapally to , and minor links like NH 204 into a single continuous NH 66 spanning 1,640 km, enhancing administrative coherence for future expansions under programs like NHDP. Implementation lagged, with signages and official updates persisting into 2011 and beyond due to coordination challenges across states.

Post-2010 Expansion Initiatives

Following the 2010 renumbering that consolidated NH66 from segments of former NH17, NH47, and NH204 into a continuous coastal corridor spanning approximately 1,622 km, the (NHAI) launched systematic widening projects to upgrade the highway to four lanes, with select high-density stretches targeted for six lanes to accommodate growing traffic volumes exceeding 50,000 vehicles per day in urban sections. These initiatives, primarily executed via (EPC) contracts, aimed to standardize right-of-way widths to 60 meters where feasible, incorporating service roads, minor bridges, and vehicular underpasses to minimize disruptions in densely populated coastal areas. By 2015, NHAI had awarded multiple packages covering over 1,000 km, prioritizing bottleneck resolutions through realignments and elevated corridors in states like and . A key component involved the four-laning of the 189.6 km stretch from the Goa-Karnataka border (km 93.700) to (km 283.300) in , contracted in phases starting around 2016 to enhance connectivity between Mangalore port and northern regions, including provisions for future expansion and utility relocations such as water pipelines. In , residual works for four-laning from the border (km 43.0) to (km 96.174) addressed incomplete segments, incorporating additional structures like bridges over local waterways completed by the early 2020s. These upgrades were funded through central allocations under the (NHDP) extensions, with physical progress reaching over 70% in non-Kerala sections by 2023, enabling design speeds of 80-100 km/h compared to prior two-lane limits of 40-60 km/h. The Pariyojana, approved in 2017 with Phase I targeting 34,800 km nationwide, integrated significant NH66 portions for accelerated development, particularly 119 km of port connectivity projects in linking coastal trade hubs, awarded as 11 packages emphasizing six-laning to support freight movement. In , where expansion faced protracted land acquisition for 3,567 hectares across the state, the 644 km from Thalappady () to Mukkola () was subdivided into 22 packages for six-laning with 45-meter widths including service roads, with contracts mobilized post-2021 and segments like Talapady to Chengala (146.3 km) opened in October 2025 after delays from environmental clearances and local protests. A Rs 990 crore package in southern , incorporating four flyovers, 36 culverts, and six minor bridges, gained momentum by 2025, targeting completion by 2026 despite statewide progress lagging at 41% versus national averages due to high land costs and density. These efforts extended to bypass constructions and junction improvements, such as elevated corridors in and to bypass congested towns, funded partly through hybrid annuity models blending central grants with toll revenues, reflecting a shift toward sustainable financing amid rising costs averaging Rs 15-20 per km for coastal terrain challenges like soil instability and flooding. By 2025, over 60% of NH66's length had achieved four-lane status outside , contributing to a national highway network expansion from 91,287 km in 2014 to 146,145 km, though Kerala-specific delays highlighted tensions between rapid goals and local ecological concerns.

Route and Geography

Total Length and Alignment

National Highway 66 extends for a total length of 1,640.66 kilometres, forming a vital coastal corridor in . The highway begins at its junction with National Highway 48 near in and ends at its junction with National Highway 44 near in . Its alignment traces a predominantly north-south path along India's western seaboard, hugging the coastline through , , and before skirting the shores of and . This route links numerous coastal urban centers, including and in Goa, , Honavar, , and Mangaluru in , as well as , , , Edappalli, , and in . The state-wise distribution of the highway's length is detailed below:
StateLength (km)
475.20
137.55
294.14
677.77
56.00

State-Wise Breakdown

National Highway 66 begins in at its junction with NH-48 near and extends southward through the state for approximately 475 km to the Goa border, traversing coastal and regions while passing through key locations such as , Rajapur, and . In this stretch, the highway connects urban centers like and Sindhudurg districts, facilitating access to ports and beaches along the coast. The highway then enters , covering about 138 km across the state's narrow coastal terrain from the Maharashtra border near Patradevi to the Karnataka border near Mapusa-Verna. It links major cities including (the capital) and , serving as a vital for tourism-dependent areas like North and South districts, with alignments often hugging the coastline and intersecting with state roads to beach destinations. In , NH 66 spans roughly 294 km from the Goa border near Majali to the border at , passing through , , and districts. Notable towns along this segment include (a and port), , , and Mangalore (a major commercial hub with an and seaport), where the highway supports freight movement and connects to inland NHs like NH-75. Kerala hosts the longest section of NH 66 at approximately 678 km, running from the Karnataka border near Kasaragod to the Tamil Nadu border near Paravur, through the state's densely populated coastal belt. The route traverses districts including , , , , , , , and , linking urban centers like , , , (with its port and airport), and the capital , while navigating challenging terrain with frequent bridges over backwaters and canals. The highway concludes in Tamil Nadu with a short 56 km segment from the Kerala border to its terminus at the junction with NH-44 near , primarily through . This final stretch connects the southern tip's tourist sites, including the and , emphasizing the highway's role in linking peninsular India's extremities.
StateLength (km)Key Locations
Maharashtra475Panvel, Mahad, Rajapur, Kudal
Goa138Panaji, Margao
Karnataka294Karwar, Honnavar, Udupi, Mangalore
Kerala678Kasaragod, Kannur, Kochi, Thiruvananthapuram
Tamil Nadu56Kanyakumari
Data as of March 31, 2019; total length approximately 1,641 km.

Infrastructure Features

Key Intersections and Junctions

National Highway 66 intersects several major , enabling efficient connectivity between coastal regions and inland networks across its 1,640 km span. These junctions serve as critical nodes for traffic distribution, port access, and regional linkages, with many undergoing upgrades to handle increasing volumes from trade and . The northern terminus occurs at in , where NH 66 meets NH 48, providing direct access from and northern industrial hubs to the coastal corridor. This junction supports high freight movement toward ports like JNPT at Nhava Sheva. Further south in , NH 66 connects with NH 166 at Hatkhamba near , facilitating links to inland routes toward and enhancing agricultural and mineral transport from the region. In , a prominent junction is at with NH 748, branching toward and northern , which aids in distributing traffic to hinterland economic zones and reduces bottlenecks in the state's tourism-heavy north.
Junction LocationIntersecting HighwayStateSignificance
NH 544Major interchange near linking to central and eastern ; features ongoing construction of 650-meter flyovers and 50-meter underpasses as of March 2025 to mitigate congestion from port and urban traffic.
NH 44Southern terminus integrating the coastal route with India's longest north-south highway, supporting end-to-end connectivity for southern tourism and fisheries.
Additional junctions, such as those near and in , incorporate bypasses to streamline flow, with six-laning projects completed or underway by April 2025 to bypass urban congestion.

Toll Plazas and Revenue Model

National Highway 66 features multiple toll plazas operated primarily under the Build-Operate-Transfer (BOT) toll model by the (NHAI) and private concessionaires, where operators collect user fees to recover construction costs, maintain , and share s with NHAI as per concession agreements. This model allocates risk to the , incentivizing efficient operations while NHAI oversees compliance and collects a portion of tolls for national highway development. Key toll plazas are distributed across states, with examples including Hativale Fee Plaza in on the Watul to Janvali section, several in such as Hejamadi and Talapady, and in locations like Kumbalam on the Edapally-Vytilla-Aroor stretch. In , plazas like Morattandi serve the Pondicherry-Tindivanam segment. As of 2025, ’s portion of NH66 has 11 operational or planned plazas spanning Karode to Thalappady, prompting local protests over close spacing, such as two within a 20 km stretch in violating NHAI’s 60 km minimum gap guideline. Toll rates are vehicle-class specific and distance-based where applicable; for instance, on the bypass, light motor vehicles pay ₹70 for a one-way trip or ₹105 return. Collections employ electronic systems nationwide, with piloting a GPS- and camera-based distance-traveled model on NH66 to replace fixed plazas, aiming for precise billing but raising concerns over implementation costs and privacy. Revenues contribute to NHAI’s overall toll income, which reached ₹55,844 in FY 2023-24 across highways, though state-specific shares for NH66 remain aggregated without public breakdown beyond concessionaire reports. No formal revenue-sharing occurs with states under toll rules, despite occasional land acquisition contributions, as in ’s 25% support for NH66 projects.

Bypass Routes and Access Controls

Several bypass routes have been developed along National Highway 66 to divert traffic from congested urban centers, enhancing efficiency for long-haul travel along India's western coast. In , the Thalassery-Mahe Bypass spans 18.6 km, connecting Muzhappilangad in to Azhikkal, operational since completion to facilitate smoother passage through the northern coastal region. The Valanchery Bypass forms a key segment in the six-laning project from Junction to its start, covering approximately 39.6 km in total with the approach, aimed at decongesting routes and boosting inter-state connectivity. Further south, the Bypass extends 26.5 km from Kazhakuttom to Mukkola, under four-laning works to circumvent the capital's urban core. In Goa, bypass initiatives include the Cuncolim Bypass, designed to avoid residential damage while improving flow through Salcete taluka, with alignment approvals emphasizing minimal disruption to local structures as of September 2025. The Bypass covers 7.97 km from km 602.930 to 610.900 near the Goa-Karnataka border, part of ongoing projects to ease southern access. Agassaim Bypass and associated flyovers, such as at Goa Velha-Siridao, integrate elevated structures to separate local and highway traffic. These routes prioritize to minimize at-grade intersections in high-density areas. Access controls on NH 66 primarily involve service roads paralleling upgraded four- to six-lane sections, segregating local vehicles like two-wheelers and autos from main carriageways to prevent mixing with high-speed traffic. In six-lane stretches, controlled entry and exit points at interchanges ensure uninterrupted flow, with new safety rules mandating compliance for all vehicles and prohibiting unauthorized access. Toll plazas, numbering 11 across Kerala sections with additional ones planned, enforce revenue collection and vehicle logging, while camera surveillance on segments like Ramanattukara-Vengalam monitors violations and aids accident probes. These features, implemented under NHAI oversight, address the highway's non-expressway status by restricting direct urban access and promoting disciplined usage amid ongoing expansions.

Operational Status

Road Conditions and Maintenance Challenges

Sections of National Highway 66 experience frequent structural failures, including embankment collapses and cracking, particularly in where multiple incidents occurred in early 2025. An expert panel appointed by the (NHAI) identified flaws in design and implementation, such as inadequate monitoring and quality checks on reinforced earth walls, as primary causes for these failures. Violations of union ministry specifications during , including the use of poor and saturated loamy soil, contributed to collapses in stretches like Km 276.78 and Km 277.160. Monsoon-induced challenges exacerbate road degradation, with heavy rainfall causing flooding, , and landslides that damage pavements and infrastructure. Inadequate drainage systems lead to persistent water accumulation, accelerating formation and surface across coastal and hilly segments. The highway's alignment through low-lying, water-prone areas in and amplifies these risks, as designs often fail to account for local and terrain stability, resulting in repeated repairs post-rainy season. Maintenance efforts face hurdles from weak soil and excessive embankment loads, prompting NHAI recommendations for ground strengthening and site-specific . In the Mumbai-Goa corridor, narrow and fragmented sections contribute to frequent accidents and disruptions, underscoring delays in widening and upkeep. Overall, lapses in proactive maintenance, including pre-monsoon renovations, and reliance on suboptimal materials hinder sustained road integrity, with NHAI inspections highlighting the need for enhanced structural oversight.

Recent Upgrade Progress (2023-2025)

The (NHAI) advanced the widening of NH66 to four or six lanes across multiple states during 2023-2025, focusing on a right-of-way expansion to 45-60 meters to accommodate higher traffic volumes and improve coastal connectivity. In , which spans approximately 643 km of the highway, 17 stretches underwent intensive upgrades, with northern sections progressing faster than southern ones; by October 2025, the Ramanattukara-Valanchery (39.68 km) and Valanchery-Kappirikkad (37.35 km) segments achieved 99.5% completion, while overall work reached about 50% by early 2026 projections despite flood-related disruptions in 2023 and 2025. Union Minister Nitin Gadkari announced in October 2025 that NHAI would complete the full Kerala length by December 2025, enabling inauguration in January 2026, following accelerated directives to contractors issued in April 2024. Four key Kerala stretches, including Thalappady-Chengala (39 km), were targeted for opening by May 31, 2025, as final construction phases concluded. In Tamil Nadu, the Kanniyakumari stretch progressed toward April 2026 completion, incorporating 93 structures such as major bridges and vehicular underpasses. The Mumbai-Goa corridor (466 km across and ) saw upgrades to reduce travel time from 12-13 hours to six hours, with initial targets for June 2025 completion, though land acquisition and environmental hurdles extended some deadlines to March 2026 or 2027. In , construction processes for the 6.5 km Navelim-Cuncolim elevated section initiated in May 2025 to address urban congestion. Karnataka's portions advanced toward a 60-meter grade-separated alignment, aligning with NHAI's broader coastal corridor goals, though specific 2023-2025 milestones emphasized integration with adjacent upgrades. Delays in select projects stemmed from right-of-way issues and terrain challenges, but overall physical progress exceeded 70% in prioritized segments by mid-2025.

Economic Impacts

Enhanced Connectivity and Trade

National Highway 66 (NH66) serves as a critical artery for coastal connectivity, linking major urban centers, industrial hubs, and seaports across , , , , and , spanning approximately 1,640 kilometers from to . Upgrades to four- and six-lane configurations under initiatives like have reduced travel times significantly, such as shortening the Mumbai-to- route from 12-13 hours to about 6 hours, thereby facilitating smoother passenger and freight mobility along the western seaboard. This enhanced linkage integrates hinterland economies with coastal infrastructure, enabling efficient access to key junctions and bypassing congested urban stretches. The highway's alignment directly supports maritime trade by connecting prominent ports including Jawaharlal Nehru Port Trust near Mumbai, New Mangalore Port, Cochin Port, and the emerging Vizhinjam International Seaport, streamlining container evacuation and reducing logistics bottlenecks. Completion of final stretches in Kerala, anticipated by late 2025, is projected to accelerate cargo throughput from Vizhinjam and Kochi by minimizing inland transit delays and enabling faster delivery to northern industrial corridors. These improvements address prior inefficiencies in freight movement, such as high congestion and narrow alignments, fostering reliable truck-based haulage for exports like spices, seafood, and minerals from southern ports. Overall, NH66's enhancements have spurred regional trade volumes and investment inflows, with adjacent districts experiencing accelerated economic activity due to lowered transport costs and improved reliability. Integration with port expansions, particularly Vizhinjam's role as a hub, amplifies India's western trade gateway potential, though realization depends on synchronized completion of access roads and median modifications. This connectivity upgrade contributes to broader logistics transformation in states like , where NH66 acts as a backbone for inter-port and inland freight distribution.

Boost to Tourism and Local Economies

The upgrades to National Highway 66, particularly the widening and four-to-six laning along coastal stretches, have improved access to key tourist destinations such as 's beaches, the region's hill stations and forts, Karnataka's coastal towns like , and Kerala's backwaters and hill resorts, facilitating higher visitor volumes. The Mumbai-Goa segment, expected to be fully operational by March 2026, will reduce travel time from approximately 12 hours to 6 hours, enabling more spontaneous road trips and day excursions that draw domestic tourists from urban centers. This enhanced connectivity is projected to increase revenue in Goa, where the highway has historically supported massive sector growth by linking inland markets to beach economies. Local economies benefit from amplified economic activity, including job creation in , , and ancillary services along the route. Improved encourages small and medium enterprises to establish operations in roadside towns, spurring for hotels, resorts, and eateries catering to . In , the near-completion of the six-lane corridor by January 2026 is anticipated to strengthen regional development through better links to ports like and , indirectly supporting by easing logistics for coastal trade and visitor amenities. Overall, these developments promote sustained income generation for coastal communities dependent on seasonal , though actual gains depend on complementary investments in local amenities.

Social Dimensions

Population Centers and Urban Growth

National Highway 66 connects numerous coastal population centers across five states, serving as a vital artery for urban hubs in , , , , and . In , it links towns such as , Pen, Mahad, Chiplun, and , with populations ranging from tens of thousands to over 200,000 residents based on 2011 census data. segment includes (population approximately 115,000) and (around 100,000). 's stretch passes through , Mangalore (urban agglomeration over 600,000), and (about 180,000). 's portion integrates major cities like (over 550,000), Kochi (metro area exceeding 2 million), (around 500,000), and (over 1 million in the urban area), while terminating near in (population about 20,000). The highway's expansion and maintenance have driven urban growth by enhancing inter-city mobility, commerce, and access to ports, prompting migration and infrastructure investments. Widening projects, particularly in and segments completed or underway between 2020 and 2025, have reduced travel times and supported hubs, correlating with rising values and suburban expansion in adjacent areas. For instance, improved NH66 connectivity has increased property demand along the route, elevating prices in coastal vicinities due to better linkage to economic nodes like ports and IT corridors. In specific locales, such as Mangalore, NH66 upgrades are alleviating congestion and bolstering port-linked development, fostering growth in neighborhoods like and Kuloor through enhanced trade and residential projects. Similarly, around , the highway's six-laning has accelerated real estate transformation, drawing investments tied to regional ports and urban extensions as of 2024-2025. These dynamics reflect broader patterns where highway access catalyzes densification and economic spillover, though growth metrics vary by local governance and terrain constraints.

Cultural and Lifestyle Integration

National Highway 66 traverses a corridor encompassing diverse ethnic and linguistic groups, including Marathi-speaking communities in , Konkani and Tulu speakers in and coastal , and Malayalam and Tamil populations in and , thereby fostering incidental cultural exchanges through heightened mobility and trade. This connectivity has amplified exposure to regional traditions, such as Goan preparations and Kerala's harvest celebrations, via roadside eateries and seasonal markets accessible along the route. In coastal fishing communities, particularly in district of , the highway's expansion from two to four lanes between and Kundapura has disrupted traditional lifestyle patterns by altering land-water interfaces critical to daily occupations. A 2020 community-led study documented impacts on over 100 affected families beyond direct land acquisitions, including blocked pathways to beaches and fishing grounds that underpin communal fishing practices and social structures tied to marine rhythms. These changes have strained intergenerational transmission in artisanal fishing, where livelihoods depend on unhindered sea access, though improved road links have enabled faster transport of catches to inland markets, partially offsetting losses for some households. Tourism development spurred by NH66 has integrated local lifestyles into broader economic circuits, with the Mumbai-Goa segment alone interfacing with 66 tourist destinations, including historical sites and beaches that draw visitors to experience authentic coastal customs like Yakshagana folk theater in . This influx supports artisan crafts and culinary traditions but introduces tensions, as commercialization risks diluting indigenous practices amid urban migration and service-sector shifts among youth. Expansion efforts have also threatened cultural landmarks, such as heritage monuments in townships, prompting local advocacy to preserve sites emblematic of historical coastal narratives.

Environmental Considerations

Terrain-Specific Engineering Demands

National Highway 66 traverses diverse terrains along India's western , including coastal plains susceptible to and flooding, lateritic hill slopes in the prone to landslides, and riverine sections requiring robust bridging. In and , the highway's alignment through steep ghat terrains demands specialized slope stabilization measures, such as retaining walls and bio- techniques, to counter monsoon-induced soil instability and frequent landslides, as evidenced by the 2024 Shirur collapse in attributed to vertical hill cutting without adequate water diversion protocols. Coastal segments, particularly in , face engineering challenges from soft, waterlogged lateritic and alluvial soils with low —often below 50 kPa—necessitating ground improvement methods like stone columns or geosynthetic reinforcement to support elevated embankments and prevent under rainfall loads exceeding five times soil tolerance. Multiple 2025 embankment failures in and Kooriyad highlighted inadequate pre-construction soil testing and drainage, where rainwater seepage into unsealed subgrades caused widespread collapses over 200-meter stretches, underscoring the need for site-specific hydrological modeling and permeable barriers. In ghat areas of () and (), lateritic soil slopes require benching, wire netting, and vegetation cover to mitigate shear failures, with stability assessments revealing factor-of-safety values dipping below 1.0 during heavy rains due to poor initial drainage and deforestation-exacerbated runoff. Deep cuttings for widening, as flagged by experts in 2025, amplify risks in these seismically active zones, demanding seismic-resistant designs and real-time monitoring systems to address causal factors like and subsurface saturation rather than superficial repairs.

Biodiversity Effects and Mitigation Efforts

The expansion of National Highway 66 has disrupted coastal and foothill ecosystems along its route, particularly through and alteration of water flows. In district, , widening from to Kundapura blocked multiple rivers, streams, and creeks, resulting in monsoon flooding and into agricultural lands, which degraded surrounding wetlands and riparian habitats. Construction practices, including stone blasting near crusher units and unauthorized soil dumping on wetlands, generated dust and landslips—such as those in Byndoor in June 2017 and Divgi village near —that further destabilized local ecology and exceeded initial (EIA) predictions. In , NH66 widening has inundated wetlands and paddy fields, as seen in Keezhattur hamlet, where bypass developments since 2018 acquired biodiversity-rich lowlands and disrupted , increasing flood risks and loss. Hill excavations for elevated sections have triggered fissures and landslides in the foothills, compromising and contiguous forest patches that support endemic . These interventions, in a , amplify broader pressures like and barrier effects on migratory , though site-specific data remain limited in available assessments. Mitigation measures mandated by the (NHAI) draw from guidelines, incorporating underpasses, fencing, and vegetation corridors to reduce vehicle- collisions and maintain connectivity in sensitive zones. The Ministry of Road Transport and Highways requires National Board for Wildlife approvals for projects near protected areas, ensuring compensatory and restoration where diversion occurs. Despite these, implementation gaps—such as non-compliance with EIA conditions on blasting and dumping—have led to unmitigated ecological overruns, prompting calls for stricter monitoring in coastal expansions. NHAI's broader practices include speed restrictions and signage in high-conflict stretches to curb road mortality, though evaluations of their efficacy on NH66 are sparse.

Safety and Incidents

Accident Patterns and Data

In , , the stretch of NH66 between Hejamady and Shiroor recorded 1,284 accidents in 2023, resulting in 222 fatalities and 1,381 injuries, highlighting it as a severe hotspot amid ongoing widening works and terrain challenges. This equates to approximately two fatalities every three days on in the district, with NH66 bearing the brunt due to high-speed traffic, sharp curves, and inadequate safety barriers. Black spots—locations with three or more fatal accidents in five years or five non-fatal accidents annually—cluster along NH66, driven by geometric deficiencies, poor signage, and mixed vehicle traffic including heavy trucks and two-wheelers. alone identifies 20 such black spots on NH66, where remedial measures like rumble strips and remain unimplemented as of September 2025. In , the 13.141 km Bypass segment features 13 black spots, with GIS analysis revealing hotspots prone to rear-end and collisions due to congestion and substandard alignments. Further south in , 48% of urban black spots under the mobility plan occur on NH66 and its bypass, often involving pedestrians and non-motorized traffic. In Maharashtra's , spatiotemporal mapping shows NH66 as the primary corridor for incidents, with four high-density crash zones linked to rural-urban transitions and seasonal tourism surges. Common patterns across states include overspeeding (contributing to 60-70% of fatalities in similar coastal highways), head-on crashes from improper lane discipline, and weather-induced slips during monsoons, exacerbated by incomplete four-laning and construction debris. Recent post-widening stretches in report spikes, such as three fatalities in two consecutive accidents in September 2025 from illegal heavy vehicle parking and elevated speeds on undivided sections. National data underscores NHs' disproportionate burden, accounting for 35.7% of accidents despite comprising 2% of roads, with NH66 exemplifying vulnerabilities in high-volume coastal routes.

Response to Structural Failures

In response to the embankment collapse on May 19, 2025, at kilometer 276.78 near Kooriyad in , , the (NHAI) attributed the primarily to inadequate subsoil exacerbated by rainwater seepage, which increased lateral pressure on retaining structures. An expert team investigated the incident alongside a similar at kilometer 277.160, submitting a final report on July 3, 2025, that highlighted deficiencies in embankment stability and reinforced walls. NHAI subsequently debarred the involved concessionaire and directed full reconstruction of the damaged stretch at its own expense, estimated at ₹80 crore, while enforcing stricter oversight on soil testing and drainage protocols. The Union Ministry of Road Transport and Highways imposed bans on the construction firm and consultancy responsible for the elevated NH-66 portion that collapsed in May 2025, prohibiting their participation in future projects pending further review. In June 2025, NHAI extended debarment to another concessionaire for slope protection failures, requiring a response within 15 days before determining additional penalties. These measures followed NHAI's submission to the on May 30, 2025, acknowledging that weak, compressible soil conditions across multiple under-construction stretches contributed to repeated failures, necessitating geotechnical reinforcements like deeper piling and improved compaction. An August 7, 2025, inquiry report revealed that collapsed and cracked sections of NH-66 in violated Ministry of Road Transport and Highways specifications, including improper reinforced earth wall that led to caving and longitudinal fissures. An expert panel confirmed on August 8, 2025, that design flaws—such as insufficient and inadequate backfill quality—combined with poor implementation caused these structural issues. In direct response, NHAI approved revised designs on August 18, 2025, incorporating enhanced specifications and mandatory third-party s for stability. Additionally, NHAI launched a comprehensive across the entire NH-66 corridor to revise guidelines, emphasizing pre-monsoon geotechnical assessments and erosion-resistant materials to mitigate recurrence in coastal terrains.

Controversies

Design and Construction Disputes

The widening of National Highway 66 (NH 66) to six lanes has encountered significant and construction disputes, primarily in , where terrain challenges including high groundwater levels, soft soils, and heavy rainfall have exposed flaws in engineering approaches. Expert panels investigating collapses of reinforced earth (RE) walls and embankments attributed failures to inadequate parameters, such as insufficient wall heights and improper geotechnical assessments, leading to cave-ins near Kooriyad in in July 2025. These incidents revealed that RE walls, intended to minimize land acquisition by retaining soil within narrower right-of-way limits of approximately 45 meters, were implemented without accounting for local , resulting in waterlogging and structural instability. Construction practices deviated from Union Ministry of Road Transport and Highways specifications, with inquiry reports documenting violations in material quality, compaction standards, and drainage systems across multiple Kerala stretches. For instance, soil nailing techniques in hilly sections failed due to poor anchorage in unstable strata, prompting contractors like the Adani Group to acknowledge methodological shortcomings. A parliamentary panel criticized the National Highways Authority of India (NHAI) for permitting multi-layered sub-contracting, which diluted accountability and contributed to substandard execution, including cracks and uneven surfacing observed in under-construction segments. E. Sreedharan, former Delhi Metro chief, highlighted that forcing a six-lane configuration into constrained widths ignored proven engineering principles, prioritizing cost savings over safety and durability. In response, NHAI admitted design deficiencies in May 2025, suspending a project director and terminating a site engineer's following a major embankment , while imposing penalties such as a one-year ban and Rs 9 fine on for a Kasaragod slope collapse attributed to faulty drainage and design. Further actions included blacklisting 12 construction firms and 17 consultants nationwide for recurrent faults, underscoring systemic issues in oversight and the adoption of untested technologies to circumvent land constraints. These disputes have delayed progress, with critiques emphasizing that designs failed to integrate site-specific data, such as embankment stability against monsoon-induced saturation, leading to repeated that compromised public safety.

Political and Local Resistance

Local communities along National Highway 66, particularly in , have mounted significant resistance to widening projects due to concerns over land acquisition, displacement, and loss of agricultural holdings. In , where the highway traverses densely populated coastal districts, protests erupted against surveys and alignment marking for the four-laning expansion under the (NHAI). These actions, initiated around 2017-2018, targeted the proposed acquisition of private lands, with agitators forming groups like the NH Action Council to demand alternative alignments or compensation revisions. A notable escalation occurred on April 6, 2018, in , where demonstrations against the widening survey turned violent, involving clashes between protesters and police; the action council claimed the project would directly impact over 1,500 families through land loss and home demolitions. Similar unrest spread to , with farmers labeling themselves "Vayalkilikal" (birds of the paddy fields) to symbolize their fight against farmland conversion, blocking officials from proceeding with acquisitions. In 2019, revenue department efforts to install alignment stones in coastal areas provoked further clashes, injuring 15 policemen and highlighting ongoing tensions over the highway's coastal alignment violating local patterns. Politically, the Kerala government under the CPI(M)-led LDF faced internal and opposition scrutiny, with the ruling party in April branding highway land agitators as "extremists" to delegitimize protests, a stance that drew backlash and accusations of suppressing legitimate grievances. The Congress-led UDF opposition capitalized on these issues, alleging inadequate rehabilitation and environmental oversight, while demanding halts to surveys until revised plans addressed local demands for bypasses or reduced land take. In Karnataka's district, community-led initiatives since 2011 have documented enforcement gaps in environmental clearances for NH66 (formerly NH17) expansion, raising parallel local concerns over ecological disruption and inadequate , though protests there remained less violent than in . These resistances have delayed segments of the widening, with demands for design modifications persisting into 2025 in northern , where material shortages and protest-induced halts pushed completion timelines to July 2026. Despite political will in states like overcoming similar hurdles through negotiations, the Kerala cases underscore a pattern where local agrarian interests clash with central mandates, often amplified by state-level partisanship.

Future Prospects

Ongoing and Proposed Widening

The six-laning of National Highway 66 (NH66) in , spanning approximately 644 km, is a major ongoing project divided into 24 reaches, with over 50% of the work expected to be completed by March 2026. The (NHAI) has targeted full completion of this section by December 2025, as stated by Union Minister , though delays of up to three months have been reported due to shortages of red soil and other materials, particularly in southern reaches where progress lags behind the north. Four stretches were opened to in May 2025, contributing to 17 ongoing widening projects in the state, most along NH66. In , widening works in the Kanniyakumari district, including elevated sections, are progressing but faced halts due to contractor issues with ; resumption has targeted completion by April 2026. Karnataka's section from the Goa border to (km 93.7 to 283.3) involves four-laning with paved shoulders as part of broader upgrades. The portion features a 45-meter right-of-way to accommodate six lanes, driven by high population density and land values, contrasting with narrower alignments elsewhere. Proposed widening includes additional toll plazas—11 planned across NH66 with two more under consideration—to support post-upgrade operations, primarily in . No large-scale proposals for eight-laning or beyond have been detailed in recent NHAI announcements, with focus remaining on completing current four- to six-lane conversions amid challenges like structural collapses, which led to a one-year ban on Megha in 2025 for lapses. These efforts aim to enhance coastal connectivity from to , though timelines remain subject to land acquisition and material constraints.

Integration with Expressway Networks

National Highway 66 integrates with India's expressway networks primarily through its role in the Pariyojana, where upgrades enhance connectivity to economic corridors and feeder routes linking coastal areas to inland high-speed highways. The highway's widening projects, including the six-laning of 643 km in from Thalappady to Karode, support faster freight movement along the Mumbai-Kanyakumari alignment, complementing expressways like the Delhi-Mumbai corridor by providing efficient coastal access to ports such as and . Spur connections further bolster this integration; for example, a initiated in March 2025 evaluates a new spur linking NH 183 (Kottayam-Kumarakom route) to NH 66, aiming to streamline traffic flow between central interiors and the coastal highway, thereby facilitating smoother transitions to broader expressway grids. Similarly, NH 766C serves as a 198.5 km spur from NH 66 in , extending connectivity to interior regions and indirectly supporting links to projects like the Bengaluru-Mangaluru corridor upgrades. These enhancements position NH 66 as a vital in the national transport matrix, with projected completion of key stretches by January 2026 expected to reduce Ernakulam-Thiruvananthapuram travel to 2.5 hours, enabling better synchronization with southern expressways such as those on NH 44. However, full expressway standards—such as —remain limited to select upgraded segments, with integration relying more on junction improvements and parallel developments under Phase I.

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