Although this is an old thread, i'd like to share my thoughts about this railroad crossing topic. The biggest problem isn't a working solution, but the overall performance. Peeps are already organized in groups. This is probably because of the load the checks on peeps are putting on the cpu cycles. There needs to be a whole package of checks for each peep roaming the park, visible or not, to simulate a more or less realistic behaviour. This is pretty complex, as they do have collision checks, so there will be cramped areas if you build your ways in front of a Zozo to narrow. Just as an example. Even if it is an extremely simple check, it has to be performed, and if you think about the sheer mass of peeps you can atttract with a good attraction, you'll probably imagine that an additional check is a performance problem. So it's wise to reduce the amount of checks, and peeps organized in groups of 4 are reducing the nescessary checks down to 1/4th. A halt, like a triggable barrier would stop all peeps running into that object. Placed somewhere with a lot of traffic, it'll put a lot of stress on your system.
So a better solution would be to use the new tool to create something like a fake station of a transport ride with an entrance on both sides and a zero time stop. Peeps would pass through normally, until a train arrives and the station would be triggered like a duelling wooden coaster. As these triggers already exist in game, the devs don't need to do anything fancy in the coding section, and it would be doable with the already existing materials. It just needs to be modded so that an entrance is looking like a simple way, which is probably possible.