Grade separation, where a level crossing is replaced with a bridge or tunnel, is a significant improvement to safety. However, almost all the benefit goes to motorists and pedestrians rather than train travellers. Therefore it is fair to fund them via Roads and Ports rather than Public Transport.

There are knock-on benefits to passengers - level crossing accidents disrupt train services, and traffic jams can hold up trams and buses. But these are minor compared with the benefit to motorists.

In terms of project management, the perfect example is the January 2007 works at Middleborough Road Box Hill. The benefits for train travellers were:

• Frequent, detailed news reports warning people what was going to be interrupted
• Timing the works to be over the summer holidays to minimise the impact of the delays
• Working around the clock to minimise the duration of the project
• Highly efficient bus services running from Blackburn to Box Hill and Laburnum
• Numerous Connex staff directing passengers
• Well planned interchanges between trains and buses

The simplest (and therefore usually most cost-effective) method of grade separation is to either lower or raise the railway. This eliminates all problems of access to side streets and residences, and allows for the redesign of the railway station for better interchange with buses and better access to local shops.