Question:  For left turn signal heads, we usually install it on the mast arm and the far side 1-b pole.  The MUTCD requires a 40 degree viewing angle from the left turn lane.  There are situations that the far side left turn signal head is outside the 40 degree angle zone due to the width of the street.  I know Caltrans doesn’t like to put the 1-b on the median too.  We required to have at least two signal heads for each moment.  So, what’s your opinion for the second left turn signal hea...

Question:  Do slower moving cars need to keep right?

Answer:  Section 21654 of the California Vehicle Code says:  (a) Notwithstanding the prima facie speed limits, any vehicle proceeding upon a highway at a speed less than the normal speed of traffic moving in the same direction at such time shall be driven in the right-hand lane for traffic or as close as practicable to the right-hand edge or curb

The word “Notwithstanding” means that even if a driver is moving 70 mph in a posted 70...

Question:  In a recent signal design, I needed the mast arm signal raised a bit higher for clearance and suggested connecting the MAS mount between the yellow and green indications.  A reviewer told me this is not a good idea, and I’m hoping for a more detailed reason why not. 

Answer:  Caltrans Standard Plan ES-4D (http://www.dot.ca.gov/hq/esc/oe/project_plans/highway_plans/stdplans_US-customary-units_06/viewable_pdf/rspes-04d.pdf) shows the MAS mounting but doesn’t really explain how th...

Question:  I’m designing a traffic signal at an intersection with a heavy right turn out of a minor street, plus a very low volume pedestrian crossing that is in conflict with the right turn move.  I’m thinking of having a right turn arrow that will display a red when there are pedestrians, and will show a green when there are no pedestrians.  The controller is a 170 with McCain software.  Here’s a sketch of what I’m wanting to do, how do I make it work? 

Answer:  McCain software h...