Nice idea in principle

It's a nice idea in principle and sounds fair but can only really be so if there is a reasonable alternative. Whilst the public transport system is still so shoddy and expensive then expansive road pricing will lead to;

Ever higher increase in house prices in towns compare to the country as people compete for housing that will save them from having to pay to use roads.

The poor being shoved out further and further as they can't afford to compete for the housing

The poor getting poorer because they now commute the furthest and so have to pay by usage.

To put it another way a pay by usage scheme doesn't really reflect a choice by the travelling public. The poor will not be choosing to travel further and therefore pay more. They will simply be forced to do so by being poor and there being not alternative. So it simply becomes another regressive tax.