> For heavy traffic, though, they're useless as the car flow of one entry/exit can take over the roundabout and block all other entries. Not wrong, but traffic

> For heavy traffic, though, they're useless as the car flow of one entry/exit can take over the roundabout and block all other entries. Not wrong, but traffic lights can be added to roundabouts as well ("signalized roundabouts") * https://www.youtube.com/watch?v=XCrAPcUzOdw https://www.youtube.com/watch?v=XCrAPcUzOdw So if an intersection is (e.g.) four-way, and one particular entrance monopolizes things than it can be given red at times and the others green (and than one-green/three-reds). See (e.g.) "Performance and Safety of Roundabouts with Traffic Signals" by Tracz and Chodura: > The paper presents designs, advantages and some drawbacks of various layouts of roundabouts with traffic signals, used in urban arterials on crossings with large traffic volumes. The authors analyze signal settings with alternative phasing used at intersections that can provide the intersection capacity of about 6500 veh/h in 2x2 lanes arterials or even 8000 veh/h in 2x3 lanes arterials. Accident statistics for roundabouts with traffic signals in Krakow are also given and discussed. In addition, presented are practical examples of changes of signalized roundabouts geometry; reconstruction into a form of turbo- roundabout and its effects regarding traffic safety and good performance. * https://pdf.sciencedirectassets.com/277811/1-s2.0-S1877042812X00247/1-s2.0-S187704281204390X/main.pdf?X-Amz-Security-Token=IQoJb3JpZ2luX2VjEDwaCXVzLWVhc3QtMSJGMEQCIE5WnkghO3ym2nZRbP0OiLhErx7SZMjhN2tGQ7fJv1%2BlAiA%2FEVEi10pDddQmTyzb5BsNSF5kJZeLUI%2BG6J9BruWwQSqyBQhlEAUaDDA1OTAwMzU0Njg2NSIMqGTQKVNtZjngJrwSKo8FQLAk%2FtcRFu0H5G2NZ8v4aYVe%2FAqFQj7hS7sZAlb7vqq84U%2FaJTlLto2VYGFrvgSQ5sgUBpCW4doiqejjJzlHdgXlUSZhdHCqT3laELbuamgjHZK8yCWnThDhUxz885rxJb%2Fu4oxU9K4kGHqLtFHVQ5Ff29STia0R2BncttigbbsFHN2eJgCp7bqcuAHTV6ik5zG88m6RelL1ILu%2FRUIb%2FuJSUDxHtIE9Ln9gR3YWiHApZkzJnTfbIv5rDKih0UL6PiI07YsX%2BSGjdmbilECV5XQeLLiqpHXWQFsfhlqcBE6RD6BabVhRw42R9k3CAkuJ%2BYTqOWu%2Bl11j%2BT%2FDam2RALWb48bQDZlmN1uOUXyc5bLVwzP0sf4vFjVDzmWgs3Ap8SHwDifCCu0i8NfDoU91HVkJSdihb8XSN4mdV0lEdB0h1LrDKRa60VU90kC3ZUx1TNl00TDfoynBdaBdrOcRJYSWj01Ioecu8daIoF31n1zxjKkLD7H3OZtkll0q%2FbdJu2yionKn0KDa2UcM8t%2BCckacz9F2BF1EZXMH0DwBDvtt%2BwYaUyREuG5899Wa9IFhw6yAdzFq%2FcOA2LB8U15%2FrO9jjJC2lbsK4OrLTqCkWh23UJ3KwvOTjvNIbeejodrGt0tjHq0rRHKb%2FCsMdJDE%2BN1WFacGZxYwc01vxobdOas5aE0HKDAZxpYdRSK3naMAxfNJwTENYA9IHLOdmTJosaYTt15I5CWLWfzuhV9jG%2BnLyoWe9T%2FkRAQYywK18C9S0MJ9tDGz6pfV7HD2BDSb%2BxD5y7UVCZmptypQXb2QDaiMBTtCOq2JsInDObHRnifQ7%2BlCjbZAJpz4wQU44Ef5eggm2Mam9UoiCXJU8OOEVjCS5OWpBjqyAeHpnPdjraHUzg80EWT8lKyBIdwnAzPz3A2uAPF6FEhft5i%2Bi%2B7M0f9e37nJ30SR5gXjljYMNUQptYRRxoKhP%2F8UmNJUUCzwQ6Px%2F4e5WzZDnbAvN72JlH1CLUKTO7U%2Fgxi3OsNZUZ4QPBzet9rTHQyN%2Fr2wNBnEJoiUyKTYkF697%2FAHoyaI9bTTabw9NRSfB4AL2ONezr2tIu5jF0ZaziLY1%2B04BckG3n%2BgBRph%2B1Nm2vw%3D&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20231025T203857Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=ASIAQ3PHCVTY6RVOT4WD%2F20231025%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=6221ad8d5af1785a45e1d39e00bef345de017380fc95fa3e0086e62177ae870d&hash=18bd6a8629a15ca415690d47786abf64c2e357d86dffc9e0df5f2697cedbd635&host=68042c943591013ac2b2430a89b270f6af2c76d8dfd086a07176afe7c76c2c61&pii=S187704281204390X&tid=spdf-c05f0068-701e-4a37-a7a6-aea8542e82f6&sid=1a03793351ba33443788f464e78bba693df9gxrqa&type=client&tsoh=d3d3LnNjaWVuY2VkaXJlY3QuY29t&ua=19015856020a5a56545e&rr=81bd442079863a00&cc=ca https://pdf.sciencedirectassets.com/277811/1-s2.0-S187704281... And §8.1 Traffic Signals at Roundabouts: * https://www.fhwa.dot.gov/publications/research/safety/00067/000678.pdf https://www.fhwa.dot.gov/publications/research/safety/00067/... Also: * https://www.access-board.gov/research/prow/literature-roundabout-signalization/signalization-of-roundabouts/ https://www.access-board.gov/research/prow/literature-rounda...