Of course, the industry chain is the beginning and the end and everything in Simutrans. So, the whole chain, and the whole transporting network, once it grows very big, gets very complex at transporting goods. On slower computers, you should not exaggerate in routes count and vehicles count. Plan very wisely your routes and vehicles. Use of multiple routes which serve the completely same stations is not advised, except in exceptional circumstances. Better is using the hub system. Industry chain is sometimes simple, i.e. waste incubator, just one station, a little bit more complicated, i.e. gas station (oil rig->refinery->gas station), or gets very complicated,if you serve the big markets.

Of course, to choose simple industry chains, for example waste incubator industry, is very simple, but gets boring very quick. More profit do the complex industry chains bring, or even the whole supply to a customer (market, the end consumer). At the beginning, a good strategy is to bring some bulk goods to a power station and build a power grid back to the source of the goods. That way, the feedback chain is established. Power brings more productivity and greater rates, the goods are produced quicker, which can be quicker transported to the power station, which in turn produces more power, until the maximum quantity is reached. This power can of course also be used to stimulate production at other industry chains.

Key to successful network is not to use the sheer number of vehicles, but to use adapted convoys, i.e. trains (in principle the best transportation means in Simutrans) of adapted length, using in account the length of the route, and the congestion of the route.

Some vehicle types are cheaper to get, and have their own route partially built (trucks, buses), other, like ships have the route, but are more expensive to build. Trains also need their route. So do the trams and monorails. Only planes do not need any ground route at all. It is the best practice, to connect already build parts of road, truck etc. This saves expenses. By building railway tracks, the adequate type should be used. It makes no sense to build a electrified 300 km railway track for a single 110 stream coal train. Too expensive.

One good trick is to use the same vehicles shared for some industries (where possible) on their longest route. What do I mean? Let's use the example industry chain from crude oil to gas station. You can use the same vehicles (the same road vehicles or the same rail convoy or the same ships etc.) all the way, if you choose a direct route: oil rig->refinery->gas station. It is even possible, that they physically lay different, i.e. gas station->oil rig->refinery. Just make a route assignment in the correct order. The tank vehicles can transport both oil and gas, so the whole industry chain can be served by only one vehicle, or a long enough convoi(i.e. train). This is also sometimes the case in reality. The same can be applied for i.e. a part of industry chain : oil rig->electronics factory->market. The piece goods vehicles transport both plastic and electronics. This way you can effectively use your existing vehicles, and make more profit. This layout is, however, not appropriate for all industry chains/parts of them.

The fewer physical vehicles you use, that fewer problems exist at crossings of paths.