Sorry, but the map looks incredibly ugly. Also, it also looks almost uplayable for TTT, as it’s pretty much one open area, with an exception of these four towers.
Put more effort and detail in the environment. The road is a borderless block of concrete placed on the completely flat grass. Try making the terrain more hilly, varied and random. Add some buildings around the road, and make the general environment make atleast a bit of sense, not just randomly scattered props.
For example, why is there a random playground and a water tower with two tanks and a sewer pipe?
Connect these areas with a (non-blocky) road, either made out of blended displacement, or a brush partially sinked in the grassy hills.
The towers are extremely monolithic, with an unfitting texture. Make the tower look more complex. Here’s an example of a watchtower.
It’s a lot more complex, not just a block of metal with some holes in it. Anyway, who would make a metal-plated tower like that?
Also, the walkways appear to be glass, right? Make them look more durable and less free-standing. There’s no way they could be floating above the ground like that without any supports. Also, walking on these would be tedious, as they’re almost featureless.
I’ve noticed a small hole in the tower’s glass floor as well. Make it look more visible, I can imagine many people falling to their death because they didn’t notice it.
Your skybox texture is badly stretched, you have to put _hdr behind it’s name. For example, sky_day01_01**_hdr**.
Also, as your map is for TTT, it needs more closed areas, where all people aren’t visible at once. Traitors would get easily revealed in your map, and would have no chance to escape from the fight.
I’m aware that it’s your first map, but that doesn’t give you an excuse to make it bad. You have to put more effort and time into your map in order to be appreciated. Also, try playing some more maps to get some reference about how should is properly look. Check out this: rp_downtown_v2, ttt_clue_pak, some of the Half-Life 2 levels and real life buildings / environment.
Also, sorry for the words, but you’ll eventually understand.
I’ve done this for your good, not to insult / embarass you.
Regarding your original question, you have to put a func_tracktrain on the van’s inner floor. Tracktrain causes the players to “stick” onto it’s floor, so they don’t slide away as it moves / turns.
This is what I mean.