What is the Speed on a Dual Carriageway?
The speed on a dual carriageway in the UK is not a single, fixed limit but varies depending on the type of vehicle you are driving and whether there are specific posted signs indicating otherwise. Generally, for cars, the national speed limit applies, but this is capped at 70 mph. However, other vehicles, such as vans, lorries, and cars towing caravans, have lower maximum speeds, and all vehicles must adhere to any lower limits indicated by signage.
- Car speed limit is typically 70 mph.
- Other vehicles have lower limits.
- Always obey posted signs.
- Conditions can necessitate slower speeds.
Dual carriageways are a significant part of the UK's road network, designed for faster traffic flow than single-carriageway roads. They are characterised by a central reservation separating traffic travelling in opposite directions. While they offer greater capacity and safety features, they still require diligent adherence to speed regulations to prevent accidents and ensure efficient movement of traffic. Drivers must be aware that the presence of a dual carriageway does not automatically mean a 70 mph limit applies to all vehicles at all times; local variations and vehicle types are critical factors.
Understanding these nuances is paramount. It's about more than just avoiding a fine; it's about contributing to a safer road environment for everyone. Factors such as weather, traffic density, and the condition of the road surface can all influence the appropriate speed, even if it's below the legal maximum. This article will delve into the specific limits, the factors affecting them, and how to make informed decisions about your speed when navigating these roads.
Understanding Dual Carriageway Speed Limits: The Basics
When you encounter a dual carriageway, the first thing to establish is the governing speed limit. For a standard car, the national speed limit for dual carriageways is 70 miles per hour (mph). This limit is generally indicated by the absence of any other signs, signifying the default maximum. However, this baseline is subject to several important caveats. Critically, this 70 mph limit only applies to the carriageway itself and not to sections such as slip roads, which often have lower limits.
It is vital to recognise that a dual carriageway is defined by its central reservation. If there is no central reservation, it is considered a single carriageway, and different speed limits apply. The road markings, including the reflective studs between lanes and the presence of a physical or grassed central median, are key indicators. Navigating these roads safely involves constant vigilance, not just for the speed limit signs but also for the road's configuration and your vehicle's capabilities.
The 70 mph limit is the absolute maximum for cars. Many drivers mistakenly believe all dual carriageways are 70 mph zones. However, local authorities can and do impose lower speed limits on certain dual carriageway stretches due to factors like sharp bends, proximity to residential areas, or junctions. Always look for signs. An end of dual carriageway sign will also indicate a change in speed restrictions, often reverting to the national speed limit for single carriageways (typically 60 mph for cars) or a different posted limit.
Car Speed Limits on Dual Carriageways
For cars (and motorcycles), the default maximum speed on a dual carriageway in the UK is 70 mph. This limit is set by national legislation and applies unless specific signs indicate a lower speed limit. It is crucial to remember that this is a maximum, not a target. Driving at 70 mph might be inappropriate or unsafe under certain conditions, such as heavy rain, fog, or dense traffic. Road conditions, visibility, and the behaviour of other road users must always be taken into account when deciding your actual driving speed.
What Speed on Dual Carriageway for Other Vehicles?
The speed for dual carriageway driving differs significantly for vehicles other than cars. These limits are in place to account for differences in handling, braking distances, and stability. For instance, cars with a trailer (or towing a caravan) are restricted to a maximum of 60 mph on dual carriageways, and this limit also applies to certain types of vans and other lighter commercial vehicles. Heavier vehicles, such as lorries (over 7.5 tonnes gross vehicle weight) and buses, have a lower limit of 60 mph, which applies to both single and dual carriageways.
It is essential to be aware of the specific class of vehicle you are driving and its associated speed limits. Exceeding these limits can lead to penalties, and more importantly, can compromise the vehicle's safety and control, increasing the risk of an accident. Always check your vehicle's documentation or signage if you are unsure about its classification and its legal speed limits on different road types.
Motorways vs. Dual Carriageways: A Speed Distinction
While many dual carriageways share characteristics with motorways, particularly in their design for higher speeds, there can be a subtle distinction in speed limits and regulations. Motorways, by their nature, are designed for the highest speeds and generally have a 70 mph limit for cars. However, not all dual carriageways are treated the same as motorways. Some dual carriageways are classified as 'A' roads or 'M' roads, and while they might have a 70 mph limit for cars, they may also have more frequent junctions, varying road surfaces, and different safety features compared to a dedicated motorway. A contraflow system on a motorway, for example, will always have significantly reduced speed limits, often down to 50 mph or less, which is more restrictive than typical dual carriageway limits.
The Impact of the National Speed Limit
The concept of the 'national speed limit' is crucial. For dual carriageways, the national speed limit for cars is 70 mph. For single carriageways, it is 60 mph. This means that if you are on a road with no specific speed limit signs, you must adhere to these default national limits based on the road type and your vehicle. However, 'national speed limit' signs themselves often have a blue circle with a red border and a number inside, but on dual carriageways, it's the *absence* of signs that often implies the 70 mph limit for cars. It's a common misconception that all roads with two lanes in each direction are automatically 70 mph zones; the distinction between a motorway and a dual carriageway that is not a motorway is important, and local authorities can lower this limit on any road.
Understanding the legal speed limit is only the first step; driving at a safe speed appropriate for conditions is paramount.
The "end of dual carriageway sign" is a visual cue that the road characteristics are changing. Drivers should anticipate a change in speed limits and potentially road layout as they pass this marker. It typically signifies a transition to a single carriageway or a road with different traffic management, such as entering a town or urban area, where lower limits are standard.
Factors Influencing Safe Driving Speed
While legal speed limits provide a framework, driving safely on a dual carriageway involves more than just adhering to the posted numbers. Numerous environmental and situational factors dictate the *appropriate* speed, which may be significantly lower than the legal maximum. These considerations are crucial for preventing accidents and ensuring the safety of yourself and other road users. Ignoring them can lead to dangerous situations, even when driving within the legal limit.
Weather Conditions
Adverse weather is perhaps the most significant factor influencing safe driving speed. Heavy rain can drastically reduce visibility and cause aquaplaning, where tyres lose contact with the road surface. Fog significantly impairs visibility, making it difficult to judge distances and react to hazards. Even strong winds can affect vehicle stability, particularly for larger vehicles or those towing trailers. In such conditions, reducing your speed well below the 70 mph limit is not just advisable; it is essential for maintaining control and stopping distances. A good rule of thumb is to match your speed to the visibility and road surface conditions, often halving your speed in dense fog or during heavy downpours.
Traffic Flow and Congestion
Driving on a dual carriageway during peak hours often means navigating through congested traffic. Attempting to maintain a high speed when surrounded by slower-moving vehicles is dangerous and counterproductive. It increases the risk of rear-end collisions and makes lane changes hazardous. It is important to observe the general flow of traffic and adjust your speed accordingly. If vehicles are moving significantly slower than the legal limit, you should reduce your speed to match them, maintaining a safe distance. A contraflow system on a motorway, for example, invariably leads to reduced speeds and increased congestion, necessitating a patient approach.
Road Surface and Condition
The condition of the road surface plays a vital role in determining safe speed. Potholes, loose gravel, oil spills, or worn tarmac can all compromise tyre grip and vehicle stability. On a dual carriageway, encountering such hazards at high speed can be catastrophic. Drivers should remain alert for any deviations in the road surface, especially after periods of bad weather or roadworks. Reflective studs between motorway and slip road sections, or indeed on the carriageway itself, indicate lane boundaries but can also highlight changes in road surface or potential hazards. If the road surface is compromised, reducing speed significantly is prudent.
Road Layout and Junctions
Dual carriageways, while designed for faster travel, are not without their complexities. Sharp bends, steep gradients, and the approach to junctions or slip roads all require a reduction in speed. Drivers must anticipate these changes in road layout well in advance. Speed limits are often lowered approaching major junctions or where the carriageway narrows. Likewise, when exiting a dual carriageway via a slip road, drivers must slow down considerably to navigate the curve safely and merge with traffic on the connecting road. The speed limits on slip roads are typically much lower than on the main carriageway, often around 40-50 mph.
Vehicle Load and Condition
The load your vehicle is carrying and its overall condition significantly impact how it handles and stops. A vehicle laden with passengers or heavy goods will have longer braking distances and may be less responsive to steering inputs. Similarly, a vehicle with worn tyres, brakes, or suspension will not perform optimally. It is crucial for drivers to be aware of their vehicle's limitations and adjust their speed accordingly. For example, a car towing a caravan or trailer must adhere to a lower speed limit (60 mph) on dual carriageways due to the increased length, weight, and altered handling characteristics.
Adjust your speed proactively based on what you see ahead – signs, bends, traffic, and weather – rather than reactively when a hazard is upon you.
Legal Implications and Enforcement
Exceeding the speed limit on any road, including a dual carriageway, carries significant legal consequences. Understanding these implications is crucial for all drivers. The enforcement of speed limits is carried out through various means, including speed cameras, police patrols, and average speed check systems. Awareness of these enforcement methods can help drivers maintain compliance and avoid penalties.
Penalties for Speeding
In the UK, speeding offences typically result in a fixed penalty notice, which includes a fine and penalty points endorsed on your driving licence. The severity of the penalty is usually determined by the speed recorded relative to the posted limit. For instance, exceeding the 70 mph limit on a dual carriageway by a small margin might result in a lower fine and fewer points, whereas a significant excess could lead to a court summons and potentially a driving ban.
For cars caught exceeding 100 mph on any road, or exceeding the 70 mph limit by more than 30 mph, a court appearance is mandatory. This can lead to much harsher penalties, including substantial fines and more penalty points. For commercial drivers, exceeding speed limits can also affect their professional licences and livelihood. The cumulative effect of penalty points can also lead to disqualification from driving if a driver accrues 12 or more points within a three-year period.
Types of Speed Cameras
Various types of speed cameras are deployed to monitor speeds on dual carriageways and other roads. These include:
- Gatso cameras (speed camera vans): These are often located in fixed positions and use radar to detect speeding vehicles. They capture images of offending vehicles, including their speed, registration plate, and driver.
- Hologram cameras: Similar to Gatso cameras, these also use radar technology.
- ANPR (Automatic Number Plate Recognition) cameras: While primarily used for other purposes, ANPR systems can also be integrated with speed detection.
- Average speed cameras: Increasingly common, these systems measure a vehicle's average speed over a set distance, often between two points on a dual carriageway or motorway. This system makes it harder to avoid detection by simply slowing down briefly.
The presence of these cameras serves as a deterrent, but drivers should not rely on their absence to speed. Enforcement can occur anywhere, and police officers can issue tickets based on visual estimation or handheld speed detection devices.
Police Enforcement and Patrols
Beyond fixed camera sites, police patrols actively enforce speed limits. Officers in marked or unmarked vehicles can monitor your speed directly. They may use handheld or vehicle-mounted speed detection devices. If an officer believes you are speeding, they can stop you and issue a ticket or, in more serious cases, require you to attend court. Police presence on dual carriageways and motorways is a visible reminder of the importance of adhering to speed limits.
Driving Too Slowly: A Hazard?
While the focus is often on speeding, driving too slowly on a dual carriageway can also be a hazard. If a driver travels at a speed significantly below the flow of traffic, especially in the outside lane, they can cause congestion and frustration, potentially leading to dangerous overtaking manoeuvres by other drivers. The Highway Code advises drivers not to drive unnecessarily slowly or obstruct traffic. If you are not comfortable driving at the prevailing speed, it is often safer to use a lower-speed road or pull over when it is safe to do so to let faster traffic pass.
The legal framework surrounding speed limits is designed to balance traffic flow with safety. Understanding these rules and the consequences of breaking them is a fundamental aspect of responsible driving on UK roads.
Navigating Dual Carriageways Safely: Practical Tips
Driving on a dual carriageway can be a different experience compared to smaller roads. The higher speeds and multiple lanes require a heightened sense of awareness and proactive driving. Implementing certain strategies can significantly enhance your safety and the safety of others on these busy routes.
Lane Discipline
Effective lane discipline is paramount on dual carriageways. The general rule is to keep to the left-hand lane unless you are overtaking. The right-hand lanes are for faster traffic and overtaking only. Never overtake on the left. When you have finished overtaking, move back into the left-hand lane as soon as it is safe to do so. This keeps the faster lanes clear for those who need them and reduces the risk of sudden braking or weaving by other drivers.
Overtaking Safely
Overtaking on a dual carriageway requires confidence and careful observation. Before starting an overtake, check your mirrors and your blind spot to ensure the lane you intend to move into is clear. Signal your intention clearly and in good time. Accelerate briskly to pass the slower vehicle, but do not exceed the speed limit. Once you have passed the vehicle and can see its front in your rear-view mirror, check your mirrors and blind spot again before signalling and moving back into the left-hand lane.
Maintaining Safe Following Distances
The 'two-second rule' is a fundamental guideline for maintaining a safe following distance. Identify a fixed point on the road ahead (e.g., a sign or a bridge). When the vehicle in front passes that point, start counting 'one-thousand-and-one, one-thousand-and-two'. If you reach the same point before you finish counting, you are too close. This distance should be increased in adverse weather conditions or when following larger vehicles that may obscure your view.
Using Slip Roads and Junctions
Slip roads, whether for entering or exiting a dual carriageway, require particular attention. When joining, accelerate on the slip road to match the speed of the traffic on the main carriageway. Look for a gap in the traffic and merge smoothly. When exiting, signal well in advance and move into the left-hand lane if necessary before taking the slip road. Be aware that speeds on slip roads are often lower, so begin to decelerate on the slip road itself.
Awareness of Contraflow Systems
Be prepared for contraflow systems, especially on motorways or major dual carriageways undergoing maintenance. These systems involve traffic being directed into lanes travelling in the opposite direction, separated by temporary barriers. Speed limits are invariably reduced in these zones, often to 50 mph or less, and the road layout can be more complex. Always adhere strictly to the reduced speed limits and follow directional signs carefully.
Always anticipate potential hazards rather than just reacting to them; look far ahead and plan your actions accordingly.
Dealing with Roadworks and Diversions
Roadworks on dual carriageways often necessitate speed restrictions, lane closures, and diversions. Signs will typically indicate reduced speed limits, often to 50 mph or less. Be patient, maintain a safe distance from the vehicle in front, and follow the temporary signage. These areas can be unpredictable, with narrow lanes and sudden changes in road surface or direction. A contraflow system on a motorway, for example, is a common feature of major roadworks that requires extra caution.
By applying these practical tips, drivers can navigate dual carriageways with greater confidence and safety, making their journeys smoother and more secure.
Dual Carriageways vs. Motorways: Key Differences
While both dual carriageways and motorways are designed for higher-speed traffic and often share similar characteristics, there are crucial distinctions that drivers must understand, particularly concerning speed limits and road rules. Recognizing these differences ensures compliance and safety.
Definition and Design
A dual carriageway is a road that has a central reservation to separate traffic travelling in opposite directions. It typically has two lanes in each direction, but may have more. A motorway is a specially designed high-speed road, also with a central reservation, but motorways have stricter regulations. For example, certain vehicles (like learner drivers, smaller mopeds, and agricultural vehicles) are prohibited from using motorways.
Speed Limits
For cars, the national speed limit on both motorways and dual carriageways is generally 70 mph. However, this is where the similarities often end in practice. Motorways are designed with fewer access points and junctions, generally leading to more consistent traffic flow. Dual carriageways, especially those that are not classified as motorways, may have more frequent junctions, roundabouts, and connections to local roads, often resulting in lower statutory speed limits being imposed locally. For example, a dual carriageway passing through a built-up area might have a 50 mph limit, whereas the motorway equivalent would be 70 mph.
Access and Junctions
Motorways are accessed via slip roads and have limited, well-spaced junctions. Dual carriageways, particularly those not designated as motorways, can have more varied access points, including traffic lights, roundabouts, and direct access to properties in some instances. This higher density of junctions and varied access points on non-motorway dual carriageways can lead to more unpredictable traffic movements and a greater need for drivers to be vigilant and adjust their speed accordingly.
Road Markings and Signage
While both road types use clear signage, motorways often have distinct blue signage indicating their status and upcoming junctions, whereas dual carriageways (especially A-roads) might use green signage, similar to other main roads. Reflective studs between motorway and slip road sections are common, but the overall road environment on a motorway is typically more uniform and designed for sustained high-speed travel without interruption.
Contraflow Systems
Contraflow systems are more commonly associated with motorway or major dual carriageway maintenance works. In these situations, traffic is diverted into lanes heading in the opposite direction, separated by temporary barriers. Speed limits are significantly reduced, often to 50 mph or below, regardless of whether it's technically a motorway or a dual carriageway. These temporary arrangements demand extra caution and strict adherence to signage.
Vehicle Restrictions
As mentioned, certain vehicles are prohibited from motorways. This includes learner drivers, motorcycles under 125cc, vehicles not built for speeds over 25 mph, and vehicles towing trailers where the trailer's width exceeds that of the towing vehicle. These restrictions do not typically apply to dual carriageways that are not designated motorways, meaning you might encounter a wider variety of vehicles on a non-motorway dual carriageway.
Ultimately, while the 70 mph limit for cars is a common factor, the overall environment, access points, and potential for variable limits make it essential to treat every dual carriageway and motorway with respect and to always check and obey posted signs.
Speeding vs. Driving Too Slowly on Dual Carriageways
The discussion around speed on dual carriageways often centres on the dangers of driving too fast. However, driving unnecessarily slowly can be just as hazardous, creating risks for yourself and other road users. A balanced approach that considers both extremes is vital for road safety.
The Perils of Speeding
Exceeding the legal speed limit on a dual carriageway, whether it's the 70 mph maximum for cars or lower limits for other vehicles, significantly reduces your reaction time. The higher the speed, the longer it takes to perceive a hazard, brake, and stop. This is compounded by the fact that braking distances increase exponentially with speed. A speeding vehicle has a reduced capacity to manoeuvre around unexpected obstacles, such as debris on the road, sudden braking by the vehicle ahead, or an animal darting out. The consequences of an accident at high speed are also far more severe, leading to greater risk of serious injury or fatality. Moreover, speeding can lead to substantial fines, penalty points, and potentially the loss of your driving licence.
The Hazards of Driving Too Slowly
Conversely, driving significantly below the speed limit, especially in the outside lane, can be equally dangerous. This can cause:
- Frustration and Aggression: Other drivers may become impatient, leading to aggressive driving behaviours like tailgating or risky overtaking.
- Traffic Congestion: A slow-moving vehicle, particularly if it's in a lane meant for faster traffic, can create bottlenecks and slow down the overall flow of traffic, leading to congestion.
- Increased Risk of Overtaking: Drivers attempting to overtake a slow-moving vehicle may be forced to accelerate sharply and manoeuvre into potentially unsafe gaps, increasing the risk of collision.
- Unpredictable Actions: A driver who is excessively slow might also be prone to hesitation or making unexpected decisions, contributing to hazardous situations.
The Highway Code advises drivers not to drive unnecessarily slowly or obstruct traffic. If you are not comfortable maintaining the general flow of traffic, it is often safer to use a lower-speed road, pull over when safe to do so, or use the left-hand lane and allow faster traffic to pass.
Finding the Right Balance
The 'right' speed is not always the legal maximum. It is the speed that is appropriate for the conditions. This means driving at a speed that allows you to:
- See and react to hazards in time.
- Stop safely within the distance you can see clearly ahead.
- Maintain control of your vehicle at all times.
- Observe and adhere to all posted signs and road markings.
This often means driving at or near the speed limit when conditions are optimal – good visibility, dry roads, light traffic, and a well-maintained vehicle. However, it requires reducing speed significantly when any of these conditions deteriorate. The presence of reflective studs between motorway and slip road sections, or indeed on the carriageway itself, can also be a prompt to check your speed and awareness, as they often denote changes in road layout or potential hazards.
The Role of Vehicle Type
It is also important to remember that different vehicles have different capabilities. A car towing a caravan or a large van will not accelerate or brake as effectively as a standard car. Therefore, drivers of these vehicles must be particularly mindful of their speed and ensure it is appropriate for their vehicle's limitations, even if it means travelling below the 70 mph limit for cars. The 60 mph limit for vehicles towing trailers on dual carriageways is a recognition of these limitations.
Never assume the left lane is always the slowest; it is the lane for normal traffic flow and for those intending to continue on the dual carriageway, not necessarily only for the slowest drivers.
Ultimately, safe driving on a dual carriageway is about adaptability and judgment. It requires constant assessment of the road, traffic, weather, and your vehicle's capabilities to select a speed that is both legal and safe.
Understanding Signage and Road Markings
Effective interpretation of road signs and markings is fundamental to navigating dual carriageways safely and legally. These visual cues provide critical information about speed limits, lane usage, and potential hazards, ensuring drivers can make informed decisions about their speed and position on the road.
Mandatory Speed Limit Signs
The most direct indication of speed limits comes from mandatory speed limit signs. These are typically circular with a red border and a black number indicating the maximum speed in miles per hour. On dual carriageways, you will see these signs to indicate the 70 mph national speed limit for cars, or any lower imposed limits (e.g., 50 mph, 40 mph) in areas with specific risks like sharp bends, junctions, or roadworks. It is crucial to remember that the 70 mph limit is for cars and motorcycles; other vehicles, such as lorries and cars towing trailers, have different, lower limits.
National Speed Limit Signs
When the national speed limit applies, you might see signs indicating this. For dual carriageways, the national speed limit for cars is 70 mph. If no specific signs are present, this is the default limit. However, it is important to note that the 'national speed limit' symbol itself (a red-bordered circle with a black diagonal bar) usually signifies the 60 mph limit for cars on single carriageways. On dual carriageways, the *absence* of any other speed restriction signs is what typically indicates the 70 mph limit for cars.
End of Dual Carriageway Sign
The 'end of dual carriageway' sign is a clear indicator that the road's characteristics are changing. This sign typically marks the transition to a single carriageway road or a road with different speed restrictions, such as entering an urban area. As you approach this sign, you should be prepared for a reduction in speed limits and potentially a change in road layout, such as the absence of a central reservation. This transition point is often associated with a change from the 70 mph limit back to the 60 mph national speed limit for single carriageways, or a lower limit if signs indicate.
Road Markings
Road markings provide essential guidance. White lines mark the edges of the carriageway and lane dividers. On dual carriageways, the central reservation is often marked by a white line and reflective studs. Similarly, reflective studs between motorway and slip road sections, or along the edge of the carriageway, help delineate lanes, especially in low visibility conditions. The left-hand edge of the carriageway is usually marked by a continuous white line, while broken white lines separate lanes travelling in the same direction. The lane closest to the central reservation is typically for overtaking.
Contraflow Systems and Roadworks Signage
During roadworks or when a contraflow system is in operation, temporary signage becomes critically important. These signs are usually orange or yellow and convey essential information about reduced speed limits (often 50 mph or lower), lane closures, and diversions. Following these temporary signs precisely is paramount for safety, as the road layout may be significantly altered. A contraflow system on a motorway, for example, will have extensive temporary signage to guide drivers through the altered lane configurations.
Understanding Junctions and Slip Roads
Signage for junctions and slip roads is designed to help drivers navigate these complex areas. Exit signs are usually green and indicate the junction number and destinations. Slip roads themselves often have their own speed limit signs, typically lower than the main carriageway, to account for the curves and merging traffic. Drivers must pay close attention to these signs to adjust their speed appropriately before entering or exiting the main dual carriageway.
Look for signage ahead, not just at the last moment; anticipate upcoming changes in road conditions and speed limits by scanning well in advance.
By understanding and obeying all signs and markings, drivers can ensure they are travelling at the correct speed and in the appropriate lane, contributing to a safer journey on dual carriageways.
Frequently Asked Questions About Dual Carriageway Speeds
Here are answers to common questions drivers have regarding speed limits on dual carriageways.
What is the speed on a dual carriageway?
The speed on a dual carriageway for cars is typically the national speed limit of 70 mph, provided there are no signs indicating a lower limit. However, this limit is reduced for other vehicle types like lorries and cars towing trailers.
What speed on dual carriageway for a car towing a caravan?
Cars towing caravans or trailers are restricted to a maximum speed of 60 mph on dual carriageways, regardless of the posted limit for cars.
Are dual carriageways and motorways the same speed limit?
For cars, the national speed limit on both dual carriageways and motorways is generally 70 mph. However, dual carriageways not designated as motorways may have more variable lower limits imposed locally due to junctions or other factors.
What is the speed limit if there are no signs?
If there are no signs indicating a specific speed limit on a dual carriageway, the national speed limit applies. For cars, this is 70 mph. For vehicles towing trailers or larger vans, it is 60 mph.
What is the speed limit in a contraflow system?
During a contraflow system, speed limits are significantly reduced, typically to 50 mph or less, for safety reasons. Always adhere strictly to the temporary signs provided.
What is the national speed limit for a dual carriageway?
The national speed limit for a dual carriageway in the UK for cars and motorcycles is 70 mph. For other vehicles, it is lower, generally 60 mph.
When can I drive faster than 70 mph on a dual carriageway?
You can never legally drive faster than 70 mph on a dual carriageway as a car driver in the UK, as this is the national maximum speed limit for this road type. Driving at 70 mph should only be done when conditions are safe and appropriate.