U Turns

Overview

Use these features to control where vehicles can make U-turns (180° turn, allowing them to travel back the way they came).

Vehicels can do a U-turn at:

• The end of dead ends / cul-de-sacs
  • This is vanilla game functionality, and is always enabled
• Junctions
  • This optional TM:PE functionality can be applied city-wide, and/or customised for each road at a junction

U-turns can help simplify and shorten vehicle routes, but at junctions they can disrupt oncoming traffic.

Usage

There are two ways to enable U-turns at junctions:

• Junction Restrictions, or
• Lane Connectors (create a link from an incoming lane to an outgoing lane on the same road)

To use them, the features must be enabled in Maintenance Settings.

Applicators

If you want to customise individual junctions, use either the Junction Restrictions or Lane Connectors tool.

If you want to set the default for all junctions, use the Vehicles may do U-turns at junctions option in Policies settings.

Realistically, U-turns are impractical on smaller roads (which usually require a three point turn). U-turns are best suited to medium/large roads, particularly those with a central median.

Technical

The vanilla game allows U-turns at terminal nodes. TM:PE allows you to extend that functionality to transition nodes and junction nodes:

• U-turns can only happen if there is a left-pointing (RHD) / right-pointing (LHD) lane arrow
• Cars must be able to reach the turn lane.
• Check whether there are sufficient lane changing points in front of the turn lane.

If TM:PE is presented with multiple ways to turn a vehicle round - for example driving round the block vs. U-turn at a terminal node vs. U-turn at a junction - it will favour the option with the fewest number of lane changes.

As a U-turn is technically always 1 lane change, vehicles would always U-turn at junctions and transitions. However, this doesn't happen in real life; U-turns are cumbersome and sometimes dangerous, so drivers generally prefer a slightly longer (easier and safer) route. To mimic this behaviour in game, TM:PE treats U-turns at transition and junction nodes as 2 lane changes; drivers will look for a nearby alternative before doing a U-turn. This value is defined by the UTurnLaneDistance setting in Global Configuration. A lower value makes U-turns more desirable, a higher value makes them less desirable.

FAQ

Does this affect frame rate or cause lag?

No. Although the pathfinder has to do a few additional checks (for u-turn settings) the increased availability of u-turn locations helps many vehicles find shorter paths to their destination.

My city is a grid layout, should I use U-turns?

Grid layout provides lots of opportunities for vehicles to turn round, however U-turns might still be useful on some arterial routes - particularly in locations where there might be few alternate opportunities for vehicles to turn around.

See also

• Lane Changes
• Nodes, Segments, Lanes