Two-way streets are one of the basic building blocks of modern cities. They can provide all levels of transit service depending on their size, and, compared to one-way streets, they can make transit routes visible and easier to understand, with service running in both directions on the same street.

In all contexts, improving the transit function of congested two-way streets remains a challenge of balancing dynamic traffic movements, local access, and an inviting public realm. Multiple modes may be competing for scarce street space, and often require management to keep them moving efficiently. Street design tools can improve transit function at all scales and reduce the need for ongoing enforcement.