Category Archives: Engineering


Hot on the heals of budget deals, deficit raising, and spending cuts in Washington comes a report from the American Society of Civil Engineers saying that our failing infrastructure will impact the US Gross Domestic Product by 2.7 trillion dollars by 2040. All due to funding gaps between what we use and what we actually pay to maintain. This will cause 400,000 lost jobs, lower incomes, lower spending, and lower exports, worsening the US trade position. Transportation is quite possibly the MOST important infrastructure to a first world economy, it would be a shame to have made decades of investment to watch it crumble. Care about your transportation systems? Vote accordingly and write your congressmen, both local and national.

Full story: Reuters

Waging War on Left Turns

Left turns are terrible. When they aren’t extremely hazardous for drivers, they cause significant delays for other movements in the intersection because of dedicated left turn phases. Engineers have been plagued with this problem for years and have come up with many solutions, but usually the public doesn’t want anything to do with them. Even when they work exceptionally well, the Jughandle, the Michigan Left, and the all-powerful SPUI (single point urban interchange) all took time to introduce to the public. Even the roundabout is feared in areas where drivers don’t use them often, and the super-street causes uproar over driveway access to businesses. A personal favorite of mine, one I studied extensively in an unconventional intersection design course, is the Diverging Diamond Interchange. I designed a hypothetical DDI for Raleigh back in undergrad. It’s neat, but it’s been a hard press on the public to try something as different as driving on the wrong side of the road.

But out of left field comes a fantastic article from Slate, and it made the rounds on the internet this week from departments of transportation and other users on twitter, to an article in Infrastructurist. I was very excited to see something so fantastic shown in promising light because good publicity could be exactly what this idea needs to see more widespread adoption. The intersection does many things well. First and foremost, it removes left turns by placing left-turning vehicles on the opposite side of the road (on or under an overpass) before their turn, allowing them to make free-flowing turns. But it also removes a whole phase from two signals, reducing delay time and easing congestion for through vehicles, while reducing conflict points and making a safer and more efficient journey through the intersection.

Will these see wide spread adoption? Will it replace the traditional intersections we see today? It may replace a few diamonds, but not many cloverleafs; its power is best used on roads of different functional classes. If it can prove it’s worth in the ring of battle, it may see a limited adoption at problem locations. By and large, innovations such as the DDI help alleviate traffic in cat-and-mouse games of congestion, but as we continue to build suburb after suburb without rethinking sprawl, land use, and public transportation, count on seeing and learning to use even wackier intersections in the future. If you want to reduce travel time and congestion, anyway.

Photo Credit: Google Maps

Transportation Civil Rights

A new transportation bill is going to decide how the United States spends money on transportation for the next six years. Unfortunately, those to whom this legislation has the most impact have the smallest voice. According to the Leadership Conference on Civil and Human Rights report “Where We Need to Go: A Civil Rights Roadmap for Transportation Equity“, most funds only cover highways and very little public transportation. Millions of poor and working-class people are cut off from being able to go anywhere because the average cost of owning a car is around $9,500 a year and the current poverty level is at $22,350. I’ve long been a proponent of public transportation for it’s efficiency but it’ll never work as well in the United States as it does in countries in Europe due to our population density. This does NOT mean we don’t need it. We sprawled ourselves out much too far and built too many roads out to suburbs, roads that require upkeep and gas taxes to maintain. Now we pay the price for making the wrong investments without seeing the true cost of a highway system that squeezes every dollar out of American transportation funding.

Public transportation is very important in urban areas, and without it, many can not get to the job they need to live the American dream. It seems that the millions of Americans who have always had access to a personal vehicle don’t understand the lives of people who don’t, and don’t want to pay for them to have an opportunity to work and contribute to society. As a country we need to rethink our transportation policies, so that highway drivers understand the real cost of an American transportation system, and mass transit is finally given the funding it needs to become useful to Americans in highly populated areas.

Full article in Wired.

Graduate Lab Testing

Someone shared this video with me recently and I wanted to post it. It’s a video showing numerous contained demolition experiments for graduate student projects at the NC State Constructed Facilities Laboratory. I worked in this lab in the summer of 2006 on many graduate theses, and at least one of these experiments I recognized from actually standing nearby when the beam exploded. Others I recognize from projects I worked on, but I may not have been present for, such as the experiment on adding FRP (fiber reinforced polymer) strips to steel beams to increase their strength.

Enjoy the video. The music is fantastic.


Railroad Grade-Crossing Hazards

Two weeks ago, an unfortunate collision occurred at a railroad grade crossing in Maine. Reuters reports that a dump truck was hit by an Amtrak train and the driver was fatally wounded. Four passengers aboard the train were injured as well. Terrible. At-grade railroad crossings are some of the most dangerous intersections we have on our road system and they should be avoided whenever possible. Fortunately, many public agencies are fully aware of hazards associated with them and are taking steps to fix them. Here is a list of policies in the United States associated with at-grade crossings, published by the Federal Highway Administration. If you live in North Carolina, rest assured that NCDOT can and will use its power to remove, abandon, close, or regulate all railroad grade crossings. That is, if politicians don’t try to stop the sensibilities of the engineers there.

You might also be interested to know that railroad companies are also very aware of these hazards. CSX, for example, is “firmly opposed” to at-grade crossings and supports policies in place by the USDOT and state agencies to limit their use. You can read more about their leadership in this area on their website.

It’s a shame to see collisions on train tracks. Look both ways when you have to cross tracks and don’t, under any circumstances, try to “beat” the train or drive around protective barriers. It’s not worth it.

Full story at Gizmodo.

AutoCAD for Mac

Not exactly recent news, but exciting none the less. As an avid OS X user and fan of all Apple products, I’m very excited to see AutoCAD coming back to Mac. While a lot of designers can find their software made for Mac OS X, most engineering software is very hard to come by outside of Windows. Has anyone tested it out yet? I’m eager to hear of its intuitiveness. Along side the software, Autodesk is releasing a free mobile app for iPhone, iPod Touch, and iPad. Now we just need TransCAD on here and we’ll be all set. I’ll start holding my breath.

Full story from CNET.

What You Can Do About NC-H.561

The following is an email I sent to Wake County Representatives, concerning the issue of legislation-run engineering. If you can, write something similar RIGHT NOW to your representatives. A list of NC Representatives can be found here. Here is a list of NC Senators.

From: Mike Roselli 

Senators and Representatives,

I live in Wake County and I work in the engineering field. I’ve been made aware of H561, a bill to supersede engineering safety design decisions made by engineers at NCDOT. I urge you to NOT back this bill. It is not based on facts, research, or scientific credibility, but on fears of change. It has been well established in the engineering community that highway medians substantially increase driver safety and save many lives every year without impacting local businesses.

A research paper on this topic can be found here:

Over 30,000 people will die this year in the U.S. from motor vehicle collisions.[1] We cannot set a precedence of State legislature overseeing every engineering decision made in the name of public safety. Do we remove stop signs when businesses ask? Do we remove bridge supports when someone finds them unappealing? That is, in essence, what some are suggesting: taking the complaints of the uneducated few and using these complaints to stifle progress in public safety and safety awareness at the cost of human lives.

I have a write up on my website with more details.

Thanks for everything you do,
Mike Roselli
Wake Co Resident

1. Source: List of Motor Vehicle Deaths by Year

Mike Roselli is a graduate of the NC State Civil Engineering Department. This writing reflects the views, opinions, and judgement of the author and does not necessarily reflect the views, opinions, or judgement of NC State University or NCDOT.

Open Letter to Rep. LaRoque

The following is an email I sent to Representative Stephen LaRoque, concerning the issue of legislation-run engineering:

From: Mike Roselli 
Sent: 5/11/2011 12:42pm

Dear Representative LaRoque,

I work for NCDOT and I have studied Highway Safety at NC State. Not only do I find Bill 561 a despicable act of politics, but I find it offensive for you to imply that you know more about the engineering of highways than the engineers at NCDOT. I urge you to reconsider your endorsement of this bill and read the facts. Here is a fantastic report on how medians do NOT affect local businesses, studied by researchers at NC State and UNC:

It will be a sad day when State engineers, who work tirelessly to provide life-saving solutions for collision problems, have to report to the state legislature about every median, stop sign, or other collision-reducing counter measure they want to install.

Mike Roselli

Politics “Bypassing” Engineering

Today, the News and Observer reports that the State Senate will be voting on House Bill 561, to require NCDOT to remove a half mile of center median installed on new projects in Asheville, NC, “at a cost estimated by NCDOT at $797,500”, and to give the State legislature power over road design for other projects.

Other than ripping up a nearly completed project to nullify the design, the legislation would force DOT to change widening plans and forget other median installations planned on other routes. The fact that politicians, who know next to nothing about road design, can be influenced by their constituents to change engineered designs is unfathomably horrific.


Restricting left turns is good for safety. Median installations that require drivers to plan their left turns and u-turns at a limited number of intersections increase road safety by decreasing all sorts of collisions and allowing traffic to flow more smoothly. The decisions made in these designs were based on safety.

So who has a problem with this? Well, access restriction is seen by many locals as harmful to businesses, despite some studies showing evidence to the contrary. The latest is by a research team here at NC State and UNC, titled “Economic Effects of Access Management Techniques in North Carolina”. I’ve attached the study and you can download it here.

The study confirms that little to no evidence of economic problems was found after the installation of turn-restricting medians.

Additionally, it’s important to note that drivers are more aware of road safety than they think. And in fact, some drivers may be more inclined to use your business if they feel safer about entering and exiting the access to it. The Federal Highway Administration has a great write up on safe access and what it means for businesses. I’ve attached it and you can read it here.

The Problem

Indeed, with enough fussing to the legislator whose campaign you backed, it seems businesses may be able to “buy” the road design they want for their businesses, regardless of safety concerns. Even in the face of state budgetary concerns, it doesn’t seem to bother Rep. Stephen A. LaRoque to use another million dollars to remove a brand new installation developed in the interest of public safety. What exactly seems to be going through his mind? This:

“The legislature should have the final say on projects like this before they go through.” -Rep. Stephen A. LaRoque

This is a problem. It is a sad day when engineers who make sound decisions based on data can have their life-saving designs overseen and rejected by bought elected officials in the name of cheap tricks and politics.

Bottom line? Let engineers do their jobs. And write your representatives an email and tell them. I did.

Source: News & Observer


It seems the Senate has delayed voting on this issue for now. I’ll be posting more on this as it develops.

New Roundabout, New Collisions

I was reading this News & Observer article today about the new roundabout on Hillsborough St in Raleigh, NC. Raleigh Police have cataloged more than 40 collisions at a new roundabout installation at it seems at least a few people have some ruffled feathers.

At first this number seems high, but it’s important to remember a few key thoughts about the safety, design and installation of new traffic patterns:

New patterns can cause collisions

It’s a fact, and one that is difficult to adjust for. New traffic patterns will confuse motorists and can cause collisions. It’s to be expected. While forty seems like a rather high number, high rates during a learning period are why safety engineers do not normally begin their investigation for at least 12 months after a new traffic pattern.

Reduction in conflict points

Roundabouts drastically reduce the conflict points at an intersection. While less conflict points do not necessarily reduce collisions, there are less places vehicles can collide, one of the large advantages of roundabouts.

Reduction in conflict speed

Roundabouts also reduce the speed of incoming traffic. When drivers approach a roundabout, they approach a yield as well as a significant turning radius to enter the circle. This reduction in speed reduces the severity of collisions in the roundabout. The magic of the roundabout is that all of this is done while still reducing delays and increasing the flow of traffic!

Collision severity tradeoffs

When evaulating safety, the number of collisions is not the only metric analysts are concerned about; severity is a metric which should be considered at great length. Without looking at detailed traffic collision reports for the area, it is impossible to determine the safety of the previous intersection. However, it should be noted that roundabouts do not normally have head-on collisions. Because of this, almost all collisions at roundabouts will be of a much lower severity than at a standard 4-way signalized intersection. In fact, only one of the over 40 reported collisions had a severe injury and it involved a motorcycle.

Of course, you should be comparing to injuries and fatalities with the previous design. But how many fender benders are equivalent to severe injuries? Or fatalities? It’s difficult to draw a line here. The following is known by many as “The Old Kentucky Formula”, an easy to use equation for an Equivalent Property Damage Only index (EPDO) based on the data provided by a field officer on the scene of a reported collision:

EPDO = 9.5 (F + A) + 3.5 (B + C) + PDO


  • FFatality: Collisions resulting in one or more.
  • AAmbulence: Injury severe enough for an ambulence to be called to the scene.
  • BBruise: A visible, but non-emergecny injury
  • CComplaint: Officer cannot visably see the reported injury.
  • PDOProperty Damage Only: No persons report an injury on scene.

The formula is an older one so many state agencies have developed their own. NCDOT has their own Severity Method treatment which can be found here.

Final Thoughts

A city safety analyst seems to be keeping tabs and will conduct an investigation after the roundabout has been in use for a full year. I think they should throw out, at the very least, the first six months of data plus the months of construction and signage installation time. The study may very well show areas that can be improved such as driver education, signage, pavement markings, lighting, etc. But judging from my own paths through the intersection and the severity of reported collisions mentioned in the article, there is no doubt in my mind that the roundabout was the correct treatment for the intersection, and while a few comments on the article from readers show a few disgruntled folks, many more applaud it for it’s efficiency. Give it some time and the frequency of the fender benders will reduce.

Mike Roselli is a graduate of the NC State University Civil Engineering Department. He works for the North Carolina Department of Transportation. The views expressed in this post reflect the judgement of the author and do not necessarily reflect the views, opinions, or judgement of NC State or NCDOT.