HCM 2010 Update – Traffic Signal Webinar (+ Ped/Bike Webinar)

Traffic Signal Webinar

I listened in to the webinar ITE hosted last week regarding the traffic signal chapters in the new Highway Capacity Manual (aka HCM).  Here are the slides from the presentation – Download New Signalized Intersection Methodology.

I'm excited about the changes in the new HCM.  I think its a much improved tool for our use.  One downside is that the methodologies are more complex and iterative, meaning you'll need software to do the calculations.  But outside of college students, I don't know anyone who was doing these calcs by hand any more.

Here are some highlights from the webinar - 

• Procedure added for actuated phase duration so the Level of Service is based on utilizing the actuated phasing instead of us traffic engineers guessing what the average cycle length is.
• Improved delay and queue length calculations based on research.  Maybe we won't have to jump straight to micro-simulation for traffic impact studies.
• Peak Hour Factor – for whole intersection, no longer by approach or movement.
• Level of Service gradation – if volume/capacity is over 1.0 intersection is listed at F even if delay would indicate better Level of Service.
• Based on dual ring controller structure.
• HCM 2010 includes only stopped vehicles in queuing calculations where HCM 2000 included slowing vehicles.

Multi-Modal Webinar

I also attended the webinar on the Multi-Modal Urban Streets methodology a month ago, but didn't write about it at the time because it doesn't seem very applicable to me.  Here are the slides from that webinar if you're interested – Download HCM – Ped – Bike – Transit Methods.  My takeaway is that we won't be incorporating these methods in Traffic Impact Studies and that the calculations can be largely skewed by inputs that are subjective.  I can see the methodology being useful for those doing a corridor study.  I'm sure the analyses will become more refined and less subjective over time.