Gradient decides who can use a street, and maps rarely show it

Everything here earned its place by changing an outcome. Nothing about street gradient is included to round the number up.

Slope is a filter on who travels

A gradient that a fit adult barely notices can make a route impossible for a manual wheelchair user or somebody with a respiratory condition. Because the effect is gradual rather than absolute, it filters people out of a route quietly instead of producing a visible barrier.

Guidance in most countries sets maximum gradients for new construction, and existing streets in hilly cities predate all of it. The length of the climb matters as much as its steepness, since a short steep pitch with a level landing is easier than a long moderate one. Level resting places at intervals, ideally with seating, convert an impossible route into a slow one for a large number of people.

Cross-fall is the underrated problem

A footway sloping sideways towards the kerb constantly steers a wheelchair or pushchair towards the carriageway, requiring continuous correction. Cross-fall exists for drainage, since water must reach the gutter, and modest amounts are necessary and unavoidable.

Measured properly, it becomes severe where footways cross vehicle entrances, because the surface dips to meet the dropped kerb and then climbs back. A street with many driveways therefore delivers a series of tilts that is more tiring than the street gradient itself. Designing crossovers so the footway stays level and the ramp is formed in the carriageway margin solves this and costs slightly more.

Steps create single points of failure

A flight of steps on a walking route removes it entirely for wheelchair users, and it makes the route hard for anyone with a heavy load. Where the alternative is a long detour, the network effectively has a hole in it that no map records as a hole. Public lifts and funiculars are the usual remedy in steep cities, and both introduce a dependency on a machine that will sometimes be out of service.

A lift that is unreliable is worse than an inconvenient ramp, because it cannot be planned around and failure is discovered on arrival. Publishing real-time status for public lifts is a cheap measure that turns an unreliable link into a knowable one.

Slope changes cycling more sharply than walking

Cycling effort rises steeply with gradient, which is why hilly cities historically recorded low cycling levels regardless of their infrastructure. Electric assistance changed that relationship materially, and cities with difficult topography have seen cycling become viable where it previously was not. The consequence is a need for secure parking and charging, since electric bicycles are heavier, more valuable and harder to carry upstairs.

At street level, route selection matters more in hilly terrain, as a flatter route that is somewhat longer will carry more people than a direct climb. Contour-following routes are harder to design because they cut across the grid, and they are the ones that get used.

Maps and tools mostly ignore it

Most navigation applications optimise for distance or time and present a hilly route and a flat one as equivalent if the timings match. Some now offer elevation profiles for cycling, and few apply the same information to walking directions where it matters just as much.

City accessibility maps that mark gradient, steps, resting places and lift locations exist in a small number of places and are unusually useful. The data is not hard to obtain, since terrain models exist for most urban areas and footway alignments are increasingly mapped. The gap is in presentation rather than in surveying, which makes it one of the more tractable accessibility problems a city could address.

Assessing a route for slope

Walk it slowly and note where you would want to stop, because those points are where seating would change who can complete the journey. Look at whether the footway stays level across driveways or dips at each one, since repeated tilts accumulate into real difficulty.

Check handrails on any sustained climb, as a rail on at least one side makes a difference disproportionate to its cost. Note surface material on slopes, because smooth stone and polished paving become hazardous when wet in a way that matters far more on a gradient. Find the alternatives, since the useful question is not whether this route is steep but whether a flatter one exists and is signed.

Everything above, in order of what to do first

1. Slope is a filter on who travels. A gradient that a fit adult barely notices can make a route impossible for a manual wheelchair user or somebody with a respiratory condition.
2. Cross-fall is the underrated problem. A footway sloping sideways towards the kerb constantly steers a wheelchair or pushchair towards the carriageway, requiring continuous correction.
3. Steps create single points of failure. A flight of steps on a walking route removes it entirely for wheelchair users, and it makes the route hard for anyone with a heavy load.
4. Slope changes cycling more sharply than walking. Cycling effort rises steeply with gradient, which is why hilly cities historically recorded low cycling levels regardless of their infrastructure.
5. Maps and tools mostly ignore it. Most navigation applications optimise for distance or time and present a hilly route and a flat one as equivalent if the timings match.
6. Assessing a route for slope. Walk it slowly and note where you would want to stop, because those points are where seating would change who can complete the journey.

The takeaway

Read the contours before the plan. A flat map hides the reason a route is empty.

Measure the walk, not the map.