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.
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.
Curious what your take would be on whether you feel that training would be required in the software applications (Synchro for example) to walk through the impact of the changes on the software. I went to Synchro training many years ago. Have you seen the updated softwae?
Mike, very good reference materials..Thank you for sharing..