By Mike Spack, PE, PTOE, President of Spack Enterprise, Founder of MikeOn Traffic
I recently sat in on a PTV webinar to learn about the key updates in Vistro 5. Here are the big ones related to implementing the 6th Edition of the Highway Capacity Manual:
- Added pedestrian delay calculations and level of service (jargon alert: LOS) grades. You need to input the sidewalk widths on each corner, the corner radii, the inbound and outbound pedestrian volumes as well as the pedestrians who round the corner without crossing a street, and the crosswalk length/width. The LOS calculations take these inputs into account and calculate a numerical score. The score is translated into a A-F LOS grade based on research on pedestrian perceptions. This implements the HCM methodology, but there are folks in the community who have issues with the subjective perception rankings. It’s not a straightforward volume to capacity engineering calculation, but it is a very useful addition to be able to do multi-modal analyses in urban conditions.
- Added bicycle delay and LOS calculations like the pedestrian analysis – based on perception research. The inputs are the roadway width, bike lane width, parking lane widths, and bike approach volumes.
- Updated the roundabout algorithms.
- Added work zone, downstream lane blockage, and sustained spillback factors (although the second two factors should really be accounted for with micro-simulations to get a more accurate snapshot of operations). I hope agencies will start analyzing the impacts of their work zone plans.
- Updated the signalized intersection inputs to account for a free right-turn lane with a yield sign.
I’m very excited to start implementing ped and bike LOS into our Travel Demand Management/Traffic Impact studies in urban areas. I’m not sure they’ll be worth the extra effort in suburbia, but I think these calculations will eventually become included in all our traffic studies.
I’m also excited about two big enhancements to Vistro that will save us significant time when preparing traffic impact studies:
- The ability to insert an intersection along a link with a right mouse click. The new intersection will retain the trip distribution paths through it.
- Add a “duplicate paths” feature to copy the trip distribution paths from one development node and copy it to a separate development node.
If you’re new to Vistro, check out my original review of the software and a post about how easy it is to analyze multiple mitigation scenarios. Vistro has revolutionized our traffic engineering practice.
