NH 31 Highway (Unnao to Siliguri/Guwahati): Route, Length, Challan, Speed Limit, Start and End

Here’s what’s worth knowing before planning around this name: today’s NH 31 runs from Unnao in Uttar Pradesh through Bihar and terminates at Gazole in Malda district, West Bengal — it does not currently extend to Siliguri or Guwahati. The route once did continue further northeast under an older highway configuration, but following India’s 2010 highway renumbering, the stretch toward Siliguri and onward to Assam was reassigned to different highway designations, primarily NH 27 and NH 17.

That said, NH 31 remains a genuinely important east-west corridor in its own right, connecting some of Uttar Pradesh and Bihar’s most significant cities. Here’s the complete, accurate picture of what this highway actually covers today.

NH 31 Quick Facts

Where NH 31 Actually Begins and Ends

NH 31 starts at Unnao, near its junction with NH 27, and runs east through Uttar Pradesh, into Bihar, and finally into West Bengal, terminating at Kodubari Morh in Gazole, Malda district, where it connects to State Highway 10. That state highway continues onward toward Hili near the Bangladesh border, but this handoff to a state road marks the genuine end of NH 31 itself.

If your interest is specifically in reaching Siliguri or Guwahati, you’d need to continue your journey via other highways beyond Malda — this isn’t a continuous NH 31 corridor all the way to the northeast, despite how the route may sometimes be casually described.

The Route Through Three States

Leaving Unnao, NH 31 passes through Lalganj, Raebareli, and Pratapgarh before reaching Jaunpur and continuing to Varanasi — one of India’s most significant pilgrimage cities, and a stretch that carries substantial religious tourism traffic year-round. From Varanasi, the highway continues through Ghazipur and Ballia before crossing into Bihar.

In Bihar, NH 31 runs through Chhapra, Hajipur, and reaches Patna, the state capital. Continuing east, it passes through Bakhtiyarpur, Mokama, and Barh before reaching Begusarai and Khagaria. The route then continues through Bihpur, Naugachia, and Katihar toward the West Bengal border.

Entering West Bengal, the highway runs through Harishchandrapur, Chanchal, and Samsi before reaching Malda and finally terminating at Gazole.

Major Infrastructure: The Aunta-Simaria Ganga Bridge Stretch

Worth highlighting specifically: the 76-km Aunta (Mokama) to Simaria (Begusarai) section was dedicated as a 4/6-lane highway in August 2025, featuring what’s described as India’s widest extradosed Ganga Bridge at 34 metres wide. This represents a genuinely significant upgrade to what was historically a more constrained crossing point over the Ganges, and travellers on this stretch should now find considerably smoother conditions compared to the highway’s older configuration in this section.

Varanasi to Patna: The Pilgrimage and Commercial Backbone

This middle portion of NH 31 arguably carries the most economic and cultural weight on the entire route. Varanasi draws religious tourism from across India and internationally, while Patna, as Bihar’s capital, anchors substantial commercial and administrative traffic. The corridor between these two cities sees a genuine mix of pilgrim travel, interstate commerce, and daily commuter movement, making it one of the busier stretches of NH 31 by traffic volume.

Ongoing Four-Laning Work

NH 31 has been undergoing phased four-laning projects for several years, sanctioned initially in 2015 by NHAI. Key stretches under active development or recently completed include Unnao-Raebareli, Ghazipur-Ballia, and Begusarai-Katihar, alongside the completed Aunta-Simaria section. If your travel plans include any of these specific stretches, checking current construction status is worth doing, since ongoing widening work can mean temporary lane restrictions or diversions in active project zones.

Road Conditions Along the Route

Given the extensive four-laning work underway, road quality on NH 31 varies considerably by section — completed stretches like Raebareli-Ghazipur offer genuinely smooth, modern highway conditions, while sections still under construction can involve narrower carriageways, temporary diversions, or rougher surfaces. The West Bengal portion, being the shortest state segment, tends to see less variability simply due to its limited length.

Speed Limits and Challan Rules

Standard national highway limits apply on developed stretches — up to 100 km/h for cars and 80 km/h for heavy vehicles — though these are largely aspirational on sections still undergoing four-laning work, where reduced speeds and construction-related caution are necessary regardless of posted limits.

Overspeeding fines follow the standard Motor Vehicles Act framework, generally ₹1,000-₹4,000 depending on vehicle category, with Uttar Pradesh, Bihar, and West Bengal each setting their own specific rates within that range. Given the corridor’s mix of completed and under-construction sections, it’s worth paying particular attention to reduced speed zones near active construction, where enforcement can be more locally focused than on fully developed stretches.

FAQs

Q1. Does NH 31 actually connect to Siliguri or Guwahati today?

Not directly under the current highway numbering. NH 31 terminates at Gazole in Malda district, West Bengal. Reaching Siliguri or Guwahati from that point requires continuing on different highway designations — this route doesn’t run as one continuous NH 31 corridor to the northeast.

Q2. Which stretch of NH 31 currently has the best road conditions?

The Raebareli-Ghazipur section in Uttar Pradesh, which is already fully four-lane, along with the newly completed Aunta-Simaria section in Bihar featuring the new Ganga Bridge. These represent the highway’s most modernized portions as of 2026.

Q3. Is NH 31 a good route for visiting both Varanasi and Patna in one trip?

Yes — both cities sit directly on the highway, roughly in the middle portion of the route, making a combined visit genuinely practical without significant detours. This stretch also tends to be well-maintained given the traffic volume both cities generate.

Q4. Should I expect construction delays if I’m driving NH 31 in 2026?

Possibly, depending on your specific route segment. Several stretches — including parts of Unnao-Raebareli and Ghazipur-Ballia — remain under active four-laning work. Checking current NHAI project status for your specific leg before departure can help you plan realistic travel times.