Wednesday, July 18, 2012

It's no accident

The lead editorial in the Lincoln Journal Star yesterday gave some props to the Public Works Department for the continuing decline in Lincoln's traffic crash rate.  Over the years, I have provided some good examples here in my blog of engineering projects that have made a significant difference in the traffic crash experience at specific locations.

These engineering projects do not happen by accident.  Rather, they are based on the analysis of traffic crash data.  These data, in turn, come from the investigative reports completed by Lincoln police officers.  Crash reports provide traffic engineers with information about the contributing circumstances, the vehicle movements, the location of the point of impact, and a variety of other information.  Lincoln can target its limited resources based on these data, so that the general public gets the biggest return on investment, and improvement in safety.

Return on investment is not something you might not always think about when you see a project underway, such as installing a deceleration lane, or converting an intersection to a roundabout.  If such an engineering change has a significant impact on the crash rate, however, there is indeed a measurable economic benefit.  Traffic crashes are expensive, creating property damage, productivity losses, medical expenses, and so forth. Using data on crash costs from the United States Department of Transportation, we can calculate the ROI of traffic safety engineering projects.  The Public Works Department has examined 33 safety engineering projects undertaken in Lincoln since 2003, with an ROI of 6:1--for every dollar invested, six dollars of loss is avoided. 

brief summary, as well as the full technical report, is available online.  


Anonymous said...

So are you for or against investigating non-injury accidents?

Steve said...

I believe that changes in road design, modifiying intersections, adding or changing traffic controls, and similar "projects" are responsible for any significant changes in traffic safety. I haven't seen much change in the way people drive, and if I had to choose, I'd say most drive worse than they did years ago.

Some of the "improvements" I like, some I don't. Making roads safer by widening shoulders, changing grades and crowns and slopes, adding turn lanes, and those kinds of things, though expensive, are great at not only improving safety, but also the flow of traffic. On the other hand, adding signs to prevent traffic movements that contributed to crashes, like no right turn on red, no left turn, right turn only, may contribute to safety, but they often impede the flow of traffic. There are many expamples, but take the no right turn on red signs; the law already says you can only turn right on red when you stop first and yield to any other traffic. If a collision is caused by someone turning right on red, it is because a driver broke the law. Either they failed to yield, or turned into the wrong lane, or an oncoming driver changed lanes in an intersection; all illegal. Ticket the driver, but don't prevent every driver who would safely make a right turn on red by making it illegal. The driver who caused the crash by failing to yield would likely have turned even if there was a sign. I especially dislike the electronic signs, as it seems they allow right turns during rush hour, and prevent them when traffic is light. Doesn't that seem absolutely opposite of what safety concerns would dictate?

I'd love to debate this more, but this is not the place.

Anonymous said...

So, if LPD stops investigating non-injury traffic crashes will the lack of data affect traffic engineering studies? It seems logical that it will be more difficult for engineers to determine what changes are needed, or what is or isnt effective to current roadway systems. I wish I had the answer to where the cost savings can be found, but I am not convinced traffic crashes are the place to find it.

Anonymous said...

I think he'd for or against whatever his boss, the mayor, is for or against, at least publicly. If his opinion differed, it's likely that he'd remain mute on the issue in question.

Steve said...

I don't think drivers are any better now than in the past (perhaps worse), but there have been improvements in the roads and traffic controls that have made a big difference in both crashes and traffic flow. I still object, though, to most of the prohibited turn signs around town, especially the electronic ones that seem to allow turns when traffic is at its heaviest and prevent them when no one is around. From a safety standpoint, it ought to be just the opposite. From a traffic flow standpoint, prohibiting otherwise legal turns causes backups and lost time and fuel. No-right-turn-on-red signs, for example, may reduce the crash rate at an intersection. However, those crashes only occur if someone broke the law in the first place. Either the person turning failed to yield, or turned into the wrong lane, or the oncoming traffic changed lanes in the intersection. Why can't we simply ticket those drivers who break the law and allow the law-abiding drivers to make their turns? If someone is willing to break the law by turning in front of oncoming traffic, they'll probably do it whether there is a sign or not. I see it numerous times a day.

Steve said...

sorry about posting twice on the same idea. When my first one didn't appear after some time, I thought I must have forgotten to click on publish.

Tom Casady said...


It's a valuable service, but if something must go, it is far less important than the Family Crimes Unit, SROs in High Schools, a reduction in the narcotics unit, and so forth. Th lower-hanging fit has already been picked at LPD, and I was there to personally hear citizens views that they would rather forego a police investigation of a fender bender than loose some bus coverage and a senior companion and foster grandparent program. Seven of eight small groups put the traffic crash investigations at the bottom of that short list.


The data would be less complete, traffic engineering would have to rely more on frequency counts and on-site observation, rather than data from crash reports about vehicle positions, directions, and movements.


I work for the Mayor. Loyalty is imperative. I can inform and I can express my opinion privately, but once a decision is made, my job is to fully support the Mayor's initiatives, which are mine, too.

Anonymous said...

Last winter I sent a letter to the editor of the Journal Star suggesting that the Unicameral should vote on repealing the helmet law while wearing a helmet on a hot day in Summer. Today would have been the perfect day for that vote. I was wearing my helmet on my trip to the Southeast Walmart at about 3:00 PM. The time and temperature clock in the gas station across the road from WalMart said it was 115 degrees.

If Bill Avery ( in my District) felt his ears burning at around 4:00 PM today it was because of my poor mood created by putting my head in that damned skid lid. A few expletives were directed at him.

Gun Nut

6:44 said...

I happen to be for doing away with the accident investigations if it saves some of the other City services.

I was just wondering what you thought if you would/could voice your opinion.