What is the point of a banked track?

A banked track lets vehicles and athletes take corners faster and more safely by tilting the surface so part of the ground’s push (the normal force) points inward, helping supply the centripetal force needed to turn. This reduces reliance on tire or foot friction, improves stability, and expands usable racing lines. From NASCAR ovals and velodromes to indoor running tracks and highway curves, banking is a deliberate design choice to manage speed, safety, and wear in turns.

How banking works

When something turns, it needs an inward (centripetal) force. On a flat surface, most of that has to come from friction between tire and pavement or shoe and track. Banking tilts the surface so the normal force has an inward component, sharing the load with friction. That means higher achievable cornering speeds before slipping, less side-scrub, and a more stable path through the turn.

The physics in one line

For an “ideal” bank angle at which no lateral friction is required, the relationship is: tan(theta) = v^2 / (r g). Here, theta is the banking angle, v is speed, r is turn radius, and g is gravity. At exactly this speed, the track’s tilt alone provides the needed inward force; at higher or lower speeds, friction adds what’s missing or counters the excess.

Practically, designers choose an angle that makes typical operating speeds comfortable and safe, while still leaving margin for traction and weather conditions.

Practical benefits of banked tracks

The following points summarize why venues and road designers use banking across motorsport, cycling, athletics, and transportation.

• Higher cornering speeds: Banking lets competitors carry more speed through turns without sliding, boosting lap times and flow.
• Reduced reliance on friction: Less lateral tire/foot grip is needed, cutting heat buildup, wear, and the risk of skids—especially valuable in the wet.
• Stability and safety: Banking helps keep the vehicle or athlete planted and aligned in the turn, lowering rollover or outward-drift tendencies.
• Multiple racing lines: On highly banked ovals, drivers can choose different lines (low to high) with comparable speed, aiding overtaking and race craft.
• Better athlete biomechanics: Banked indoor running turns reduce lateral strain on ankles and knees, helping performance and mitigating injury risk.
• Operational resilience: Banking can improve drainage on outdoor venues and contributes to predictable handling across a range of speeds.

Taken together, these benefits explain why banking is a hallmark of high-speed venues and a safety tool on everyday roads.

Where you see banked tracks

Banking shows up in sports and transport wherever repeated, reliable turning is crucial.

• Auto racing: NASCAR and other oval speedways use steep banking (often 18–33 degrees) to sustain high speeds; some modern tracks employ “progressive banking” to encourage multiple lanes.
• Track cycling (velodromes): Steeply banked bends (typically 42–45 degrees on Olympic-standard tracks) let cyclists maintain speed and stick to the surface.
• Indoor athletics: Portable or permanent banked curves counter lateral forces on tight indoor ovals, producing faster, safer turns for runners.
• Winter sliding sports: Bobsleigh, luge, and skeleton rely on banked (walled) curves to contain extreme speeds and guide the sleds.
• Highways and rail: “Superelevation” banks curves to improve comfort and limit skidding, especially in adverse weather.
• Amusement rides: Roller coasters bank turns to manage lateral G-forces, improving comfort and safety.

While the settings vary, the engineering goal is consistent: align forces so turning is controlled, efficient, and predictable.

Design trade-offs and constraints

Effective banking balances speed, safety, cost, and user needs. The considerations below shape how steep a turn can be and how it’s built.

• Target speed vs. angle: Steeper banks support higher speeds for a given radius, but they also demand careful transitions and can raise crash energies.
• Structure and maintenance: Steep banking increases construction complexity, surface stress, and upkeep needs (e.g., pavement shear, joint fatigue).
• Weather and traction: Designers factor in rain, temperature, and tire compounds; banking helps, but surface texture and drainage remain critical.
• Visibility and access: Very steep turns can limit sightlines and complicate safety access; fencing and barrier design are key.
• User diversity: Solutions must suit a range of users—elite athletes, recreational runners, or mixed-vehicle traffic—without creating undue risk.

The optimal bank is rarely “as steep as possible”—it’s the angle that best fits expected use, environment, and safety targets.

Key numbers and examples

Highway curve

For a curve radius of 250 m banked at 10 degrees, the ideal speed is about v = sqrt(r g tan(theta)) ≈ sqrt(250 × 9.81 × 0.176) ≈ 20.8 m/s ≈ 75 km/h (46 mph). Drivers can still travel faster or slower using tire friction, but comfort and safety peak near this range.

Velodrome bend

On a 42-degree velodrome bend with an effective radius near 23 m, the ideal speed is roughly sqrt(23 × 9.81 × 0.90) ≈ 14.3 m/s ≈ 51 km/h. Elite cyclists typically meet or exceed this on the banking, which is why the steep angle is essential.

Common misconceptions

Banking solves many problems, but it isn’t magic. Here are frequent misunderstandings.

• “Banking always increases speed.” Only if other factors (traction, power, safety barriers) keep pace; too much speed without support systems increases risk.
• “Friction is unnecessary on banked tracks.” It’s only unnecessary at the ideal speed; real-world conditions almost always require some frictional contribution.
• “Steeper is always better.” Excessive banking complicates construction, transitions, sightlines, and rescue access, and can amplify crash severity.
• “Banking is only for racing.” Everyday road and rail curves use banking (superelevation) to improve safety and comfort at normal speeds.
• “Banking causes more rollovers.” Properly designed banking actually reduces outward roll tendencies by better aligning forces.

Understanding these nuances helps explain why engineers tailor banking to each context rather than applying a one-size-fits-all angle.

Summary

The point of a banked track is to align physics with performance and safety: tilting the surface provides an inward force that enables faster, more stable turns with less dependence on friction. That principle underpins high-speed motorsport, velodromes, indoor running tracks, winter sliding courses, and everyday road design. Good banking is a balance—steep enough to aid speed and stability, measured enough to be safe, durable, and practical for its intended users.

What is the purpose of banked curves?

A banked curve is a turn in which the driving surface is not horizontal. Banked curves in roads and racetracks are tilted inward (i.e. toward the center of the circle) in order to help vehicles get around the turn.

Why are some tracks banked?

Imagine you’re driving on a race track, and as you speed up into the curve, you notice the track isn’t flat but tilted at an angle. That’s what we call a “banked track.” This design helps you whip around the corner without losing control and crashing into the barrier.

Is a banked track better?

“Banked tracks increase the runner’s centrifugal force in the turns and help them get better times,” says Michael Tovar, director of the track division for surface manufacturer Mondo.

What is the significance of banked tracks?

Banked curves are circular paths that are tilted at an angle to help vehicles maintain speed while turning. This design uses the force of gravity along with the normal force to create a net centripetal force, allowing cars to navigate turns more safely and efficiently without relying solely on friction.