Motivation is an interesting thing. As a manager I was always interested in how best to motivate employees to achieve what was most important for our company. Many people that I hired were motivated simply to do a great job and for these folks the best thing to do was to give them what they needed and get out of the way. The result would consistently be phenomenal.
This hasn’t seemed to be the case with traffic engineering in the U.S. The result hasn’t been phenomenal. It’s been a failure. In fact, we have the the most dangerous road system of all developed countries and, thanks to gobs of lanes and high speed traffic, some of the most uninviting places.
In The Goal Eli Goldratt makes a point of the problems that are caused by focusing too much on one single metric—efficiency. This may also be key in the failure of traffic engineering in the U.S., the seemingly single-minded focus on Level Of Service, or LOS.
One problem with LOS is that it is not a measure of level of service at all but only of level of delay for motor vehicles.
| LOS | Delay (Seconds) |
|---|---|
| A | < 10 Seconds |
| B | 10 - 20 |
| C | 20 - 35 |
| D | 35 - 55 |
| E | 55 - 80 |
| F | > 80 Seconds |
MnDOT and other agencies talk a lot about safety and about serving the needs of ‘all users’ but what apparently happens when things get down to the drawing board is the only thing left is this lone number and that is what drives the design. Safety is apparently no longer so critical. Nor are the needs of all users. Nor is the impact on people who live, shop, or work nearby. Only LOS.
This certainly makes life easier for traffic engineers. And more dangerous and unpleasant for the rest of us.
People be damned, just get the cars through.
True LOS
Let’s make LOS a better measure and align it with our goals.
Along with good flow of traffic, we want to reduce deaths, injuries and the negative impact of traffic on people who live, work or shop near our roadways. We’d like to better serve all users including pedestrians, disabled, and bicycles. Fortunately these are mostly mutually beneficial, for instance, increasing the mode share of walking and bicycling reduces motor vehicle traffic, noise, pollution, and danger. Less motor traffic decreases delay at junctions.
First, let’s include delay for all users, not just cars.
On the safety side let’s add four measures; motor vehicle (MV) deaths per capita, MV injuries, Pedestrian/Disabled/Bicycle (PDB) deaths and PDB injuries[1].
We also want to make things more safe, comfortable and inviting for active transportation — people walking, riding bicycles, or disabled — so let’s include a mode share element. This will be measured for each junction whenever possible and will be a reduction in points (improvement). Each percent improvement will be worth 3 points.
Some Motivation
Since traffic engineers don’t seem to be motivated by doing a good job and creating a great roadway system, perhaps we can motivate them with money.
Note: Though I would lump most traffic engineers I’ve encountered in to this group, there are a growing number who are fighting hard to bring the profession out of it’s antiquated 1950’s belief system that has given us the world leading death rates we have today.
Similar to pay in the private sector, let’s set the pay of traffic engineers so that 30% of their current salary is ‘at risk’ and based on the LOS that they achieve. For easy math let’s assume they currently make $100k so now $30k will depend on how well they do their job.
Since they don’t seem to like too much change let’s keep the basic LOS scoring system where the goal is as low a score as possible. So, a LOS of zero is ideal and about 25 is still their initial target and achieving that will pay 100% of their target pay. For each point better (lower score) they will receive an additional 3% and for each point worse (higher score) they will lose 2%.
| LOS Attainment | Payout % |
|---|---|
| 1 | 172% |
| ... | |
| 23 | 106% |
| 24 | 103% |
| 25 | 100% |
| 26 | 98% |
| 27 | 96% |
| ... | |
| 75 | 0% |
Since we are so far behind other developed nations and it will take some time to catch up, it wouldn’t be fair to engineers to dump this expectation on them all at once. Let’s phase it in over 5 years at 6% per year. So, in 2015 6% of their salary will be based on LOS achievement, in 2016 12%, etc.
Example:
County 96 and Hodgson Rd in Shoreview, MN. Lower right is a grade school. Other corners are a mix of office and retail. There are two senior housing coops just to the north of the image as well as a middle school. This area gets fairly high pedestrian, bicycle, and disabled traffic for a suburb thanks to the generally very good MUPs in the area.
County 96 and Hodgson Road in Shoreview.
Current LOS is B with an average delay of 19 seconds[2]. Average delay for bicycle riders and pedestrians however is about 64 seconds which gives us an overall average of 41.5[3].
Add 14.42 points for motor vehicle deaths in Ramsey County, 17.64 for pedestrian/disabled/bicycle deaths, 12.77 for MV injuries and 14.80 for PDB injuries which all gets us to 101.13.
The mode share for this specific junction is a guesstimated 0.5% for pedestrians and 1% for bicycle riders so we get a 4.5 point reduction leaving us at 96.63 points for this junction.
County 96 & Hodgson Rd (Current)
| 96 & Hodgson (Current): | Value | Weighting | Points |
|---|---|---|---|
| Delay: MV | 19 | ||
| Delay: Ped/Bicycle/Disabled | 64 | Avg | 41.5 |
| MV Deaths (per 100k population): | 2.88 | 5 | 14.4 |
| Ped/Bicycle/Disabled Deaths: | 0.71 | 25 | 17.75 |
| MV Injuries | 638.47 | 0.02 | 12.7694 |
| Ped/Bicycle/Disabled Injuries: | 59.21 | 0.25 | 14.8025 |
| 101.2219 | |||
| Pedestrian Mode Share: | 0.005 | 3 | -1.5 |
| Bicycle Mode Share: | 0.01 | 3 | -3 |
| Total Score: | 96.7219 |
So, what’s a traffic engineer to do?
Their initial goal is to get this and other junctions down to 25 or lower. Neither increases in safety nor mode share alone will likely get them there, but modest improvements in each will.
One slip lane plus 7 other lanes to cross this thing. A safe left turn for pedestrians, disabled, or bicycle riders using crossings and signals can take up to 4 minutes. I ran this junction, including MNDOT traffic volumes, by a Dutch engineer. He said that Hodgson Rd (the north-south road) would likely never be more than two lanes at any point (it’s 4 to 6 lanes here). Ramsey Cty 96 (east-west) is borderline but would likely be two lanes if this were a roundabout (which he said could be either a single or two lane roundabout) though might be four. They would never have the slip and turn lanes we have.
As a department their first focus will be on decreasing deaths and injuries across the county since this will effectively improve LOS at every junction. They’ll lower some speeds[4], begin eliminating rights-on-red and slip lanes, and introduce a lot more roundabouts. We’ll likely see fewer lanes in general and many fewer turn lanes (especially at junctions with high numbers of people).
I wonder if they’ll discover that narrower driving lanes and roundabouts decrease distracted driving and improve safety since they require a bit more attention than our wider lanes and intersections? Whatever they do, we’ll have the traffic engineers attention and now they’re focusing on our safety rather than just speeding us through intersections.
An initial target of a 33% reduction in both deaths and injuries would seem attainable (we’d need a 59% reduction to be average for all OECD nations, but that might be asking a bit much). This gets us to 61.95 and more importantly saves about 140 people from being killed by drivers each year.
I wonder who these 140 will be? Will you or I know one of them?
Increasing mode share may be the easiest. Make this and other nearby junctions very safe, comfortable, and efficient. Make walking or riding a bicycle just as good as or a better alternative than driving for short trips. With much of traffic through this junction being somewhat local (rather than long distance commuting) a mode share of 5% for pedestrians and 6% for bicycles and disabled should be reasonable and now we’re at 33.45.
Let’s not forget the mutual benefits of most of these changes. Less MV traffic, shorter light cycles, maybe a simultaneous green for people riding bicycles, and both MV and PDB delay have decreased to 18 seconds.
The result of all of this is a score of 24.95, a 103% payout, and thus a well deserved $3,000 bonus (before taxes) for our traffic engineers.
A bit more reduction in injuries or deaths gets us another point and a 106% payout.
——-
If you wonder how we’ll pay for these bonuses, the savings for Ramsey County from fewer crashes alone will more than cover the costs[5]. And that’s only the beginning of the monetary benefits not to mention all of the other benefits.
Fair? It’s not like we’ll be asking our traffic engineers to be as good as their peers elsewhere, but only about half as good. Is that asking too much?
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[1] To guard against uncontrollable fluctuations one year to the next these will be three year running averages. We’ll use deaths and injuries per capita instead of per vehicle mile travelled because our overall goal is not just safer roadways but safer communities. This will help keep traffic engineers and planners focused on their role in the big picture not on one disconnected element. For instants, they will become interested in city planning elements that reduce the need to drive as much or as far. These will be calculated on a county-wide basis.
[2] The numbers used in this example are as accurate as I’ve been able to quickly obtain. Highly accurate numbers are not critical for our example purposes.
[3] Note that these are not necessarily comparable since motor vehicles often go through without even slowing while pedestrians, bicycle riders, and disabled must always stop to push a button and wait. A MV not slowing gets a delay of 0 while a bicycle rider who gets an immediate crossing gets a 1. However, the delay for the bicycle rider is actually much greater than this one point indicates.
[4] Note I didn’t say speed limits but speeds. The need will be to reduce actual speeds not just change speed limits.
[5] Costs of police, fire, and other services for each crash as well as damage to county property.