Headway

Noun

 * 1)  Forward motion, or its rate.
 * 2)  The interval of time or distance between the fronts of two vehicles (e.g. buses) moving in succession in the same direction, especially along the same pre-determined route.
 * 3)  Progress toward a goal.
 * 4)  The clearance beneath an arch, ceiling or bridge; headroom.

Derived terms

 * make headway

Thesaurus
Great Leap Forward, advance, advancement, advancing, amelioration, amendment, anabasis, ascent, bettering, betterment, boost, career, course, driftway, enhancement, enrichment, eugenics, euthenics, forward motion, forwardal, forwarding, furtherance, furthering, gain ground, get ahead, get going, go, go ahead, go-ahead, improvement, leeway, lift, make headway, march, melioration, mend, mending, move forward, ongoing, onward course, passage, pickup, preferment, proceed, proficiency, progress, progression, progressiveness, promotion, recovery, restoration, revival, rise, rolling, rolling on, steerageway, sternway, travel, upbeat, uplift, upping, upswing, uptrend, upward mobility, way

Etymology
From head: + way:.