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Highway Junction Rules

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Aubergine edited this page Dec 19, 2021 · 7 revisions

Under construction

Use this feature to make highway traffic more realistic.

Overview

This feature implements two key changes to the way your highways work:

  1. Vehicles can only change one lane at a time (emergency vehicles are exempt from this rule)
  2. Vehicles are forced to stay in their lane when entering or exiting the highway

Enable

Activate Enable highway specific lane merging/splitting rules in the Policies settings.

Customise

Once the feature is enabled, it applies to all highways automatically. However, for best results you should make the following additional customisations...

Lane parity

At junctions, the number of incoming lanes should be equal to the number of outgoing lanes:

(todo: images)

In the image above:

  • The junction on the left is optimal - 4 lanes enter, and 4 lanes leave.
  • The junction on the right is sub-optimal - 4 lanes enter, but only 3 lanes leave. This will impair traffic flow.

The same applies to highway exits. For example, if a 3 lane highway has a 1 lane exit ramp, the remaining highway should only have 2 lanes.

Speed parity

On highway junctions:

  • Entries should have acceleration lanes which allow traffic to speed up as it joins the highway
  • Exits should have deceleration lanes which allow vehicles to slow down as they leave the highway

These speed changes help avoid collisions between traffic travelling at different speeds.

To do this, use the Speed Limits tool to create a speed gradient along the highway ramp. The end nearest the highway should be fastest, and the end nearest your normal road system should be slower.

(todo: image)

As vehicles drive up an entry ramp, their speed should increase. As they drive down an exit ramp, their speed should decrease.

FAQ

Does this reduce frame rate or cause lag?

Very little.

I've enabled the setting but nothing seems to change

Due to the large amount of traffic on highways, a decision was made not to instantly update it (it would cause huge numbers of path finder operations). So you'll have to wait a while for new vehicles to spawn to see the effects. Alternatively, you could Clear Traffic to remove all the existing traffic that's using the old rules.

Why can't I use the Lane Arrows tool?

When highway rules are active, the lane arrows are automatically set and can't be changed. However, you can still use Lane Connectors and/or the Lane Changes features if you need to apply some further customisations.

Vanilla highway roads are somewhat limited, what are the alternatives?

There are many highway, expressway, motorway, freeway, and national road assets in the Steam Workshop; notably, many have fully rendered tunnels and asymmetric variants for entry/exit lanes. Some of our favourites are:

See Also

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