Mike on Traffic

Rethinking Level of Service

The current issue of the Institute of Transportation Engineers' Journal had an interesting article in it about the City of Pasadena, California moving towards a Multi-Modal Level of Service framework for making decisions.  Pasadena recognizes that a vibrant downtown with good transit, pedestrian, and bicycle mobility will have suboptimal vehicle mobility.  This was certainly my experience in Manhattan - vehicle traffic was quite congested, but there were a tremendous amount of people getting from A to B in a reasonable amount of time because of the subways and the bicycle/pedestrian systems. 

No one would argue Manhattan needs to tear down buildings to make bigger roads - in fact they're moving the other way by turning streets into pedestrian/bicycle malls and adding bike lanes onto streets that used to be dominated by vehicles.

The article spoke about Pasadena's framework of how they make decisions.  Fred Dock and Mike Bagheri from the City were kind enough to respond to an email from me and provide a couple of initial project specific studies where they've implemented Multi-modal Level of Service (MMLOS) standards to assess transportation conditions instead of just looking at the standard vehicle Level of Service. They're early in the process and I'm hoping to see more examples of how communities are implementing MMLOS to move away from an auto-dominated infrastructure system.

The 2010 Highway Capacity Manual has many chapters related towards MMLOS - this is the way our industry is heading, but it is a slow moving tanker that needs to be turned.  Anyone out there have good project specific Transportation Impact Studies that implement MMLOS?  I'd love to share examples - maybe we can get the slow moving tanker turning a little faster.

Traffic Signals 101

Here's a guest post from Max Moreland whose been working with me for about a year now.  Here is his take on the Traffic Signals 101 class he attended last week -

The course presented a broad view of traffic signals ranging in topics all the way from why they are installed to emergency vehicle preemption.  As an EIT working in the traffic engineering industry that has been out of school for about a year, I found this to be a useful course and would recommend it to those in a similar position to myself.

Since there was such a large range of topics presented in the course, there were plenty of things that I had already seen.  Some of these things were learned in school and other things I have picked up while working, but it was nice to see it all together in one course rather than in bits and pieces.

 Here are the top five things I learned at Traffic Signals 101:

1. Signal Agreements – Who pays for what?  Traffic signals are expensive, so it is important to know how cost, maintenance and operations are split up.
2. Signal Plans – If you are going to work with signals, you will need to know how to read a signal plan and a wiring diagram.  All those dots, lines and arrows are not just there to make everything look fancy and technical; they actually mean something!
3. Flashing Yellow Arrows – These are starting to pop up all over the place and learning their proper function is very useful.
4. Vehicle Detection – I remember talking about loop detectors in school, but I do not recall going into much detail on them.  Traffic Signals 101 gets into the different types of detection and detectors used in the field.
5. Emergency Vehicle Preemption (EVP) – The operation of EVP lights is more complex than I had previously thought.  There is more to it than just detecting an emergency vehicle in the area.

The course is only offered once a year, but you can check out the course workbook on MnDOT’s website. Here's a list of the topics covered:

1. Agreements
2. Field Components
3. Introduction to Plans
4. Cabinet
5. Controller Operations
6. Field Operations
7. Head/Loop Placement
8. Pedestrians
9. Advanced Warning
10. EVP and Railroads
11. Special Provisions
12. Maintenance

Demograghy and Traffic

I attended the NCITE luncheon yesterday where Tom Gillaspy (MN State Demographer) was the featured speaker.  It was very scary and informative.  The scary/informative part (true for both the United States and Minnesota) -

• The babyboom generation (began in 1946) is magically turning 65 (age when they can collect Medicare in addition to Social Security).  Huge wave of retirements coming.
• The current twenty-somethings (GenY) strongly prefer dense/urban living.
• The above factors are driving a resurgance of inner-city/first ring suburbs.
• GenX (me) is the smallest generation out there.  Retiring babyboomers plus small generation of forty-somethings means potentially huge shortage in leadership.

Scary slide (because it leads to Medicaid type services totally engulfing Federal and State spending on our current trajectory - this slide is for MN, but Tom says MN is very representative of U.S.):

What does this aging population/change in demographics mean for traffic engineers?

• Need to be better with signage (size, location, etc.).
• Need to design facilities keeping longer reaction times in mind.
• Peak hour traffic will plateau or decrease, but non-peak traffic will go up.
• Transit plays a much bigger role moving forward.

 

 

Streets.MN Launches

Happy to report Streets.mn has launched.  I'm a bystander on this one, but a lot of the Minnesota based transportation planning bloggers are taking part.  Including Nate Hood, who started working with me last fall. Here's the mission statement from the site -

"Streets.MN explores the pressing issues facing our cities, towns, neighborhoods and the places in between.  Our mission is to expand and enhance the conversation about transportation and land use through research and informed commentary.  Streets.MN was formed because we think transportation and land use news and information in Minnesota can be done better."

 

PC-Warrants - Forecasting Hourly Volumes for Signal Warrant Analysis

Back in March I wrote about forecasting hourly volumes for signal warrants from forecasted daily traffic volumes.  It's come to my attention that PC-Warrants has a tool built in it that makes the process very easy.  If you have PC-Warrants, search under "Volume Data Wizard - ADT to Volume Converter." 

The Volume Wizard lets you put in your own hourly percentages to convert the daily traffic volume to the hourly volumes.  The default percentages in PC-Warrants are  "Default values for typical urban approach, from Pignataro's 1973 textbook."  Here's a screenshot for the data entry window.

Training Data Collection Technicians

The Florida DOT has a training program to teach their technicians how to collect data, quality control check it, and enter the data into their database/GIS system.  They train about 60 folks a year.  After about three years of offering this training course, FDOT prepared a report that analyzed the effectiveness of this class.  I have to admit, this sounds a lot more intense than the on the job training I put my folks through.

The report goes through "competency modeling" to assess what these technicians should know and then lays out a plan to appropriately train them.  The whole process is fascinating and looks like it could be applied to any training curriculum. Traffic techs and their employers should scan through the report.

I applaud FDOT for taking a step back to evaluate the cost-effectiveness of what they do.  If I worked at a large agency or firm, I would want them to evaluate employee performance and training in a similar manner.

p.s.  Thanks Don Gettner for sending this over.

Traffic Forecasting - Past Performance Does Not Guarantee Future Results

I'm working on a traffic study where the reviewing agencies asked us to prepare 20 year forecasts in addition to looking at the build out year.  Typically, we look at data trendlines on nearby roads and throughout the county to determine a "typical growth rate" for traffic in the area.  This has historically been an annual growth rate of 1 to 3%.  This often leads us to factoring traffic up 50% or more over 20 years and then layering on the traffic from the proposed development.  Factoring existing traffic volumes up approximately 50% is also how traffic forecasts are often prepared for road design projects.

I'm strongly reconsidering this approach.  Consider Figure 1 below from the Federal Highway Administration's Office of Highway Policy Information website.  From 1986 to 2006, traffic on all of our highways did fit the model of growing by about 2 to 3% a year (or 50% to 60% over the 20 years).  But since 2005, we've had a significant drop in traffic and the trendline sure makes it look like traffic growth has plateaued. 

I've also been reading through the Texas Transportation Institute's 2011 Urban Mobility Report.  They talk about the terrible state of congestion.  I'm not going to argue that congestion doesn't suck, but take a look at Exhibit 1 from their report.  Compared to 1982, congestion is indeed terrible now compared to 30 years ago.  But looking at the 2000 to 2010 data shows congestion peaked in 2005 and we're not much worse off than we were a decade ago. 

Also consider the August 2011 to August 2010 data below from the Federal Highway Administration.  From their website, "Travel on all roads and streets changed by -1.7% (-4.6 Billion vehicle miles) for August 2011 compared with August 2010."   

But maybe Minnesota's different...... NOPE.  Below is Figure 1 from Mn/DOT's Vehicle Miles of Travel Trends in Minnesota:  1992-2010 showing traffic in Minnesota has followed the national trend in plateauing.

Based on national and local trends, my conclusion is that it is very reasonable to think traffic growth has plateaued.  The punchline for traffic impact studies: the "no-build" traffic forecasts should be the same as the existing traffic volumes.  We don't need to do opening day forecasts and 20 year forecasts because they can reasonably be expected to be similar. 

And given our huge budget shortfalls, this should also mean a policy of fixing the infrastructure we have.  NOT expanding our transportation system to add capacity.

Numbers Every Traffic Engineer Should Know

I'm in a lot of meetings where I'm seen as the expert on traffic issues (shocking, I know) and I get asked  questions related to basic standards and general practice.  You can always respond you don't know the answer and you need to look it up, but you look better if you're able to rattle off the numbers from memory.  To that end, here's a list of questions and answers every traffic engineer should consider memorizing -

About how much traffic will my development generate? (round numbers based on ITE Trip Generation Report, 8th Edition)

• Single Family Houses (per unit):  10 trips per day, 1 per peak hour
• Apartments/Condos/Townhouses (per unit):  6 trips per day, 0.6 per peak hour
• Office (per 1000 sq ft):  11 trips per day, 1.5 per peak hour
• Retail (per 1000 sq ft):  43 trips per day, 3.7 per peak hour
• Industrial (per 1000 sq ft):  7 trips per day, 1 per peak hour

What's the daily capacity of a road?  (Round numbers based on Level of Service D/E thresholds in HCM 2010)

• 2 lane local street:  1,000 vehicles per day based on livability
• 2 lane (w/ left turn lanes):  16,000 vehicles per day
• 4 lane (w/ left turn lanes):  31,000 vehicles per day
• 6 lane (w/ left turn lanes):  44,000 vehicles per day
• 4 lane freeway:  72,000 vehicles per day
• 6 lane freeway:  108,000 vehicles per day
• 8 lane freeway:  145,000 vehicles per day

What's the peak hour capacity of an intersection?  (Based on Level of Service D/E thresholds in HCM 2010)

• Stop sign controlled:  35 seconds/vehicle
• Roundabout controlled: 35 seconds/vehicle
• Traffic Signal controlled:  55 seconds/vehicle

Theoretical maximum saturation flow rate per lane? (this will allow you to do quick calculations in your head to check reasonableness at big events) - 1900 vehicles per hour per lane 

What's the threshold for when you need to add a second (dual) left turn lane at a signalized intersection?  300 left turning vehicles from that leg of the intersection in the peak hour

How wide should a commercial driveway be (based on NCHRP Report 659)?

• One lane in only: 14 feet curb to curb
• Two lane, bi-directional:  24 feet curb to curb
• Three lane, one lane in with median than two lanes out: 40 feet curb to curb
• Minimum industrial driveway:  26 feet curb to curb

How big of a footprint does a roundabout take?

• Single lane diameter: 132 foot radius
• Double lane diameter:  165 foot radius

How close can we have driveways/intersections? (these are very rough rules of thumb since this is very situational)

• On a local street:  150 feet
• On a collector street:  660 feet
• On an arterial:  1,320 feet to 2,640 feet (with medians, right-in/right-outs can be 660 feet away)

 

 

Miovision Special - 10% Off at www.CountingCars.com

I didn't want to get lost in the clutter of Cyber Monday, so I'm going with Thankful Tuesday.  Type in "Miovision" as the coupon code at www.CountingCars.com to get 10% off the following turning movement count solutions:

• COUNTpad
• COUNTcam 40
• COUNTcam 120
• PC-TAS
• PC-TAS/COUNTpad Office Package
• COUNTcam 120 Starter Package
• Video Counting Starter Package 40
• Video Counting Starter Package 120

Miovision has a good system if you want to completely outsource your turning movement counting and can afford their rates.  Our system is a much more cost effective way to use video though - allowing you to utilize your own staff, keep control of your videos, control when the counting gets done, and reduce your OVERALL expenses by more than 50%.

With the CountingCars.com system, you video the intersection (up to 40 hours with the COUNTcam 40 or 120 hours with the COUNTcam 120 - clever naming, I know), you watch the video with PC-TAS video viewer/counting software, and you do the count with the COUNTpad (do up to four classificaitons, bikes, peds, and u-turns as well as the standard movements). 

The killer features of the PC-TAS/COUNTpad system are:

• the FASTER/SLOWER toggles so your people can be extremeley efficient while staying accurate
• the PAUSE button so you can take a break (anyone who's counted in the field will see the genious of being able to take a bathroom break)
• the SAVE/CONTINUE feature so you can stop midcount at the end of the day and come right back to the second you left off the next day
• count during regular business hours, Monday through Friday, from the comfort of your office

Go to www.CountingCars.com to check out our different products.  Please email me at mspack@countingcars.com or call me at 952.926.0916 if you have any questions about our products (including our rental/demo services).

Note - the "Miovision" code is good through the end of 2011.  Thanks!

Utah DOT's Innovative ThrUTurn Intersection

The Utah state DOT has come up with a creative solution to fix a congested intersection and an even more creative video to explain the problem/solution.  I am very impressed with the video below (prepared by the transportation engineering/planning firm Avenue Consultants).  Check out the project website for more information on the through/u-turn project.  For a lot more background on the ThrUTurn concept, check out http://thruturnintersections.org/.