The Crossover point is the period of time after sunset where the balance between ambient (natural) light and artificial light (street, vehicle lights) is suitable to capture both without either overpowering the other. It is this period of time where the best colour and detail can be captured in mixed light source scenes.
The length of crossover time varies depending on the time of year in Winter sunset can be at 4pm and Crossover between 4.30pm and 4.50pm and in the Summer when the sun does not set till 10pm the crossover point can extend as far as 11pm.
This image is taken at the point where the lights are as bright as the reflections ,theres still colour in the sky and the buildings stand out on the sky line.
The image was taken about 15 minutes after the previous upload,both images would of been in the "Blue or Golden Hour"