The traffic signals along Factoria Boulevard in Bellevue, Washington, generally don't flash the same length of green twice in a row, especially at rush hour.
依据上下文，green的意思应为绿灯的意思，而green本身没绿灯的意思，这里是省略了light吗？即本身应为green light.
是省略了 signal。signal有信号灯的意思。
《牛津高阶》：
a piece of equipment that uses differentcoloured lights to tell drivers to go slower, sTOP, etc., used especially onrailways and roads（尤指铁路和公路上的）指示灯，信号灯，红绿灯
再看第二句，也可知省略了 signal：
Thetraffic signals along Factoria Boulevard in Bellevue, Washington, generallydon't flash the same length of green twice in a row, especially at rush hour.At 9:30am, the full red/yellow/green signal cycle might be 140 seconds.
