Can't a tram occasionally overcome steep slopes?

A tram can occasionally overcome significant slopes, with more or less strong constraints:

• Up to 6% gradient: operation of a tramway without major constraints;
• Between 6% and 8%: operation of a tramway that is feasible but with specific constraints to be respected on the route and/or rolling stock (reinforced motorisation);
• Between 8% and 10%: a tram can run but the installation of stations or switches and crossings (switches) is no longer possible;

But beyond a 10% gradient, the operation of a tram line in satisfactory and safe operating conditions is not an option. Indeed, all the operating conditions become restrictive:

• the curves combined with the slope accelerate the wear of the rails,
• braking distances increase,
• the speed must be reduced,
• the establishment of accessible stations is constrained,
• Restart on a hill may require a reinforced engine.

For example, the T6 is based on specific tire technology. If its manufacturer announces a maximum permissible slope of 13%, the line itself does not cross a slope greater than 10%. The use of this type of technology involves a system developed by very few manufacturers, with specific cost and maintenance issues. Historic trams met requirements in terms of capacity, performance, accessibility and safety that were very different from today's requirements.