In transit speak, "headway" is the amount of time between transit vehicle arrivals at a stop. A suburban route that has a bus once an hour would have a 60 minute headway. Frequent service buses in the US often have 10-15 minute headways. Very high service transit, most often seen in subways or LRT and BRT can sometime reach headways of 2-5 minutes. Headways have a significant impact on how desirable a transit service is because they effect:
- The time penalty for missing a train or bus
- The amount of planning and preparation needed to use transit and stay on schedule
- The amount of time lost when transit schedules do not directly conform to work, school, or activity schedules
- Average wait times
Despite advantages increasing headways is difficult. It is very expensive (because of the need to add vehicles and operators), and when headways get small enough, there is an increased risk of bunching or other disturbances and delays when route and stop capacity are hit.