The mass and stopping distance of trains is what dictates the length of the space, so we are already operating at the &#x27;same safety levels that we accept for road traffic&#x27;.<p>It&#x27;s all based on the friction between the vehicle and the surface, in road vehicles that&#x27;s typically asphalt and rubber and stopping distances are relatively short because of reduced mass. In trains the materials are steel and slightly harder steel and stopping distances are <i>much</i> larger, especially when the rails are wet.<p>A loaded freight train running 55 Mph will take more than a mile to come to a full stop. A passenger train doing 100 Mph takes 750 meters to stop with emergency brakes applied. This will lead to lots of people being wounded due the fact that trains don&#x27;t normally have seatbelts, unsecured overhead luggage and people standing if the train is relatively full.<p>Trains also can&#x27;t evade, they&#x27;re tied to the rails.