Designing Roads for Majority with Pseudo-mathematics
Monday, April 26th, 2010Having spent the last week bouncing around on my motorcycle in a 20 mph cross wind, I was super sensitive to every feature on the road that is not motorcycle friendly. The most important ones are cracks on the road between lanes and at a curve and the grooves cut on an interstate to facilitate rain water flow. I encounter these grooves on bridges across the St. Johns where the winds are especially choppy. My protest against Car Tax is more challenging than I thought.
Most roadway design engineers are not motorcyclists or bicyclists for that matter. These two groups usually get left out during planning. When a co-worker asked me how my commute has been lately, I decided to bring forth the issue of grooves cut on the road surface. I made a case that it is designed for four wheeled traffic and is potentially unsafe for motorcyclists. Tires get caught in the grooves which make the motorcycle follow the grooves till they get traction back. This happens back and forth and the motorcyclist is helpless in controlling the machine efficiently. Lighter motorcycles like mine feel it more than some heavier ones. An accident at interstate speeds with moving traffic can be fatal.
Motorcyclists are about 2% of registered vehicles. My coworkers made a point that roads are designed for the majority. They argued that it is my choice of lifestyle to ride a motorcycle and the engineers should not have to bend over backwards to accommodate my personal life choices. I am sure some of his comments were friendly banter but it made me think about concept of designing for majority. It effectively puts a price-tag on the value of a motorcyclist’s life. What is an acceptable price of anyone’s life?
What determines majority?
Is it just number of registered cars v/s motorcycles? The cars win hands down. I have designed a different method of scoring majority that is fairer and somewhat biased.
It has two factors:
Factor One > Occupants per 100 lbs
Factor Two > Gallons per 100 mile per occupant
Assumptions:
- Average motorcycle = Suzuki SV 650
- Average Car = Honda Civic
- One occupant per car
- One occupant per motorcycle
- Fuel efficiencies from company websites
Factor One – Occupants in a vehicle per 100 lbs. Single rider on a 650 cc street bike that weighs 500 lbs will have a score of 1/5. A single motorist, which is usually the case, in a Honda Civic weighing 3000 lbs will have a score of 1/30. Every Honda Civic on the road is equivalent to six motorcycles. Factor One result = 6.
Factor Two – Gallons per 100 mile per occupant. A 650 cc motorcycle gets around 55 mpg (city + hwy). Therefore, the single rider uses 1.81 gallons per 100 miles travelled. A 2010 Honda Civic gets 29 mpg (city + hwy). A single occupant uses 3.44 gallons every 100 miles driven. Therefore, a Civic user is 1.9 times the fuel footprint of a motorcycle. Factor Two result = 1.9
Factor One multiplied to Factor Two gives 11.37. Therefore, each motorcycle on the road gets multiplied by 11.37 to become a car equivalent. With motorcycles being 2% of registered vehicles, for every 98 cars on the road, there were 2 motorcycles. Now, for every 98 cars on the road, there are 2 X 11.37 = 22.75 motorcycles on the road. That is a share of 18% of traffic. Even though a minority, it is not negligible any more.
There are factors such as less wear on the road by motorcycles due to low weight thereby requiring less road maintenance that I have not considered. I have also not considered how motorcycles are unfavorable in adverse weather conditions since I ride all year and it has nothing to do with considering roadway design. Noise pollution on some larger cruisers and choppers is also not considered since plenty of cars have loud exhausts and a lot of them also blare loud music. Most motorcycles don’t come with sound systems.
I am a little biased on my two factor calculation but every road designer and transportation engineer is biased towards cars. I don’t feel guilty.
All of the above rant and pseudo-mathematics mostly try to convey that cars take a front seat in any planning. Cars are convenient, safe, protected from elements and quick. Motorcycles are not that convenient, safe with proper training, not protected from elements at all but are quick. Bicycles are neither of the three but probably the safest. Bicycles are convenient if one lives in a bicycle-centric city. Cars do cost the most amount of money to purchase and operate. They suck people deeper into dependence than a commuter motorcycle does. Yet, we promote it.
We are supposed to be the smarter of the mammals!

