New HCM Methodology for Work Zone Alternatives

Applying Capacity Reductions to Account for the Effects of Work Zones

One of the more significant additions to the new 6th Edition of the Highway Capacity Manual (HCM) are equations to account for the effects of work zones.  Based on NCHRP Report 03-107, reduction factors have been developed to reduce capacity, free flow speed, and saturation flow rates in four of the analysis modules. Several state […]

Crash Analysis: Intersection Crash Rate

Guest post by Jonah Finkelstein, EIT Spack Consulting With the definitions discussed in Crash Analysis Definitions, we can now look into some of the tools provided by the Minnesota Department of Transportation (MnDOT) to help analyze crash rates around the state. This blog post will focus on MnDOT’s tool for intersection crashes known as the […]

4-Way Stop vs. Roundabout – MythBusters Experiment

MythBusters set up an experiment to determine which intersection works better – 4 Way Stop Signs or Roundabouts – check out the ten minute video below. Experiment Setup In a parking lot with barrels Single lane approaches at four legged intersection Show driver which way to go (left, through, right) as they pull up to the […]

How to Decide When You Need Micro-Simulation Analysis

Comments we often receive regarding our use of PTV Vistro in comparison to Synchro/SimTraffic are in regard to micro-simulation. Specifically, Synchro/SimTraffic is purchased as one software package while VISSIM, which is the SimTraffic equivalent for Synchro, is a separate software from PTV. In these situations, we need to step back and first determine whether a […]

HCM 6th Edition: Roundabout Calculation Changes

The 6th Edition of the Highway Capacity Manual (HCM) is out and we (and others) would characterize it as an update as opposed to an overhaul. While this new manual does contain new and interesting items, we’ll focus on roundabouts for this article. HCM2010 was ground-breaking in the U.S. for providing a new methodology to […]

PTV Vistro – Traffic Study Mitigation Made Easy

Guest Post by Bryant Ficek, PE, PTOE, Vice President at Spack Consulting. For many traffic studies, testing different improvement alternatives is a key element of the study. Things like turn lanes, different traffic control, adding/removing access, and many other options should be considered to improve traffic flow. With Vistro, we actually have two methods to test […]

Simplified Scenario Management with Vistro

Guest Post by Bryant Ficek, PE, PTOE, Vice President at Spack Consulting. If you watched our last video about Vistro, you were able to see a glimpse of how we use the software for scenario management. It’s only a brief portion toward the beginning of the video. Given its importance to our work, this aspect definitely […]

Ignore Traffic Warrants at Your Own Risk

A Lesson in Ignoring Warrants and City Policies when doing a Traffic Study

A UPS distribution center was scheduled to break ground a few months after I started as the staff traffic engineer in Maple Grove, Minnesota.  The development project was through the environmental and city approval process before I started working for the city.  A traffic study was prepared for the project the year before by a […]

3 Tips for Evaluating Intersection Sight Distance

Guest post by Jonah Finkelstein, EIT Spack Consulting Intersection Sight Distance is an important measurement in traffic engineering and comes heavily into play when analyzing access options and modifications for existing and proposed developments. The American Association of State Highway and Transportation Officials (AASHTO) A Policy on Geometric Design of Highways and Streets says, “Specified […]

Mitigation Management Using Vistro

Video Shows How Vistro is Used for Mitigation Management

Throughout the year, we have shared our insights on PTV’s Vistro modeling software. While we use a variety of modeling tools for our traffic study projects, we have found that Vistro meets most of our project needs and it’s our ‘go to’ modeling software. Recently a client contacted us regarding how we use the Vistro […]