NH 31
Unnao–Gazole Highway
Also known as Formed from stretches of the old NH 232A, NH 231, NH 56, NH 29, NH 19, NH 30, NH 31 and NH 81
990 km
Open
3 states
National Highway
Route
NH 31 runs 990 km from Unnao, Uttar Pradesh to Gazole (Kodubari Morh), West Bengal.
Crosses Uttar Pradesh, Bihar and West Bengal.
Through Unnao, Raebareli, Jaunpur, Varanasi, Ghazipur, Ballia, Chhapra, Hajipur, Patna, Begusarai, Khagaria and Katihar.
Why it matters
This is the main road along the Ganga through Bihar, and for millions of people it is the way to Patna — for work, for hospitals and for trains. It carries pilgrims to Varanasi and to Patna Sahib, and it moves grain, maize and vegetables out of one of the most densely populated farming belts on earth. It is also the one continuous road line joining eastern Uttar Pradesh, Bihar and north Bengal.
History
NH 31 links central Uttar Pradesh with northern West Bengal, staying close to the river Ganga for much of the way. It was created after the 2010 renumbering by joining several older highways into one route, including the old Ghazipur–Patna road that was once NH 19. From Unnao it runs south-east through Raebareli, Jaunpur and Varanasi, then follows the river across Bihar through Patna, Begusarai and Khagaria to Katihar. It crosses the Ganga twice — on the Mahatma Gandhi Setu between Hajipur and Patna, and again at Mokama — which makes it one of the busiest links between north and south Bihar. In 2021 the Purvanchal Expressway was opened and now ends on this highway at Haidaria in Ghazipur district. The road finishes at Kodubari Morh near Gazole in Malda district.
Good to know
- About 990 km long, from Unnao in Uttar Pradesh to Gazole in West Bengal.
- Crosses the Ganga twice — on the 5.75 km Mahatma Gandhi Setu between Hajipur and Patna, and at Mokama.
- The Mahatma Gandhi Setu is one of the longest river bridges in India.
- Passes through the holy city of Varanasi and the ancient city of Patna.
- A new six-lane Ganga bridge between Aunta (Mokama) and Simaria (Begusarai) opened in 2025 beside the 1959 Rajendra Setu.
- The Purvanchal Expressway from Lucknow ends on this highway at Haidaria, near Ghazipur.
- Rajendra Setu at Mokama, opened in 1959, was the first bridge built across the Ganga in independent India.
- A different road from the famous old NH 31 to Assam — most of that older route is now numbered NH 27.
Timeline
- 1959Rajendra Setu, the road-and-rail bridge over the Ganga at Mokama, opens
- 1982The 5.75 km Mahatma Gandhi Setu opens between Hajipur and Patna
- 2021The Purvanchal Expressway from Lucknow opens, ending on this highway at Haidaria in Ghazipur district
- 2025A six-lane Ganga bridge from Aunta (Mokama) to Simaria (Begusarai) opens beside Rajendra Setu
Key junctions
- Unnao — the western end, on NH 27 between Kanpur and Lucknow
- Varanasi — crosses NH 19 and meets NH 35, which comes in from Prayagraj
- Haidaria (Ghazipur) — the eastern end of the Purvanchal Expressway joins the highway here
- Hajipur–Patna — the Mahatma Gandhi Setu carries the road across the Ganga into Patna
- Mokama — meets NH 33, which heads east along the Ganga's south bank
- Gazole (Kodubari Morh) — the eastern end of the highway, in Malda district
Engineering highlights
- Mahatma Gandhi Setu — 5.75 km across the Ganga between Hajipur and Patna, opened in 1982; its worn concrete deck was rebuilt in steel, finished in 2022
- Rajendra Setu, Mokama — a 2 km road-and-rail bridge over the Ganga opened in 1959 — the first bridge built across the Ganga in independent India
- Aunta–Simaria Ganga bridge — a 1.865 km six-lane bridge opened in August 2025 next to Rajendra Setu, built at about ₹1,870 crore
On the road
The Mahatma Gandhi Setu into Patna is the choke point — it can crawl at rush hour and around festivals, and the new Mokama bridge is now the quicker way across for traffic heading to Begusarai and north Bihar. Thick fog slows the whole Uttar Pradesh and Bihar stretch through December and January. Around Chhath Puja and Diwali the road fills with people travelling home, and even the four-lane sections are shared with a lot of slow local traffic, so average speeds stay low.
More details
- Lanes
- Mix of 2-lane and 4-lane sections; 6 lanes on the new Ganga bridge at Mokama