Ationale for Human-Powered Vehicle Design and Use

CHAPTER

Rationale for Human-Powered 1 Vehicle Design and Use

his book is about the design of vehicles with wheels that are powered by hu- Tman muscles alone. These can provide affordable, sustainable, and healthy transportation to people around the globe. The term Human-Powered Vehicle, or HPV, is sometimes used to denote a sub-class of vehicles including only high-performance bicycles or tricycles equipped with aerodynamic fairings. More generally, the term refer to any semi-recumbent bicycle. But the term should properly refer to any means of carriage, conveyance, or transport that is powered solely by human muscles. Manufacturers of bicycles, canoes, kayaks, and scooters do not market their products as HPVs, but surely all of these qualify for the name. Hybrid human-powered vehicles such as mopeds and electric bikes use human power in addition to other sources. While these vehicles are outside our definition of HPVs, they are certainly similar, in both technology and philosophy. Human-powered vehicles were originally designed for transportation, and that is still their most important use. HPVs today provide clean, quiet, and efficient transportation. In most developed countries, and in particular the United States, the primary transportation systems are powerful and inefficient, generating large amounts of air and noise pollution. HPVs may be chosen simply because it is pleasurable to travel quietly through the countryside, experiencing nature rather than blocking it out behind steel and glass. They may be chosen because in some cases HPVs provide mobility that no other vehicle can. Couriers in congested cities use bicycles because they are faster. Campers and fishermen in areas such as Minnesota’s Boundary Waters or Ontario’s Algonquin Park may choose a canoe because no other vehicle can traverse the lakes, rivers, and portages quite so

ASME_Design of Human Powered Machines_Ch01.indd 1 Manila Typesetting Company 04/01/2016 02:57PM Design of Human Powered Machines well. Many choose human power because it is significantly less expensive than other alternatives, or perhaps because it is good for their health. Athletes and those with a competitive bent can find many venues for racing. Perhaps the most compelling reason to use HPVs is sustainability: the environmental footprint of HPVs is typically much, much smaller than that of other modes of transportation. Despite these commonalities, HPVs are used by a variety of different people for a wide range of diverse reasons, including recreation, competition, cost, health, transportation, and concern for the environment. This book is limited to design of land human-powered vehicles. There are many reasons why the design and use of such vehicles is beneficial. In developed countries, using an HPV in lieu of an automobile (or in lieu of a second automobile for a family) can save $5,000 to $10,000 each year, while improving health and reduc- ing emissions of greenhouse gasses and pollutants. Greenhouse gas emission will be reduced by more than 4,000 kg per year due to the corresponding reduction in energy consumption of more than 17,000 kWh. In addition, infrastructure for cycling is far less costly than highways designed for automotive traffic. It is appro- priate to look more deeply into the benefits of HPV use.

Recreation HPVs, including both land and water vehicles, are frequently used for recreation. Often a bike ride or a canoe trip is a social event with friends and family. Quiet streets and rural roads can offer excellent cycling. The number of bicycle paths is increasing in many parts of the United States as abandoned railroads are converted into rail-trails and as local, state, and national parks provide more bike trails and paths. These facilities provide scenic routes for day rides, and can provide a sense of security for young riders, their parents, and others who are concerned about riding in traffic. Increasingly, the trails are long enough to use for multi-day trips. Streams, rivers, lakes, and coastal waters provide a rich range of environments for canoeists, kayakers, and rowers. A quiet pond or small stream may be an ideal place to get away for a while with a small paddle craft, while white water offers kayakers thrills and challenges. Many regions of the country have waterways that are restricted to human-power, either through law or in practice due to the nature of the lake or river.

Competition Racing HPVs has likely existed as long as human-powered vehicles them- selves. It is easy to imagine a group of tough and intrepid cyclists racing their

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high-wheeled ordinary cycles over roughly paved roads in the nineteenth cen- tury. As bicycles became more advanced, the competition undoubtedly became faster, but perhaps no keener. Today, bicycle racing is an extremely popular sport in many parts of the world, especially Europe. Competitors can find venues for racing a variety of human-powered land and water craft, and several competitions have involved aircraft. HPV organizations provide many venues for racing recumbent vehicles, including very fast streamliners. Often these events showcase technological developments and design innovation. Many are local or regional events, sponsored by clubs. Of the more traditional races, the most well known is the Tour-de-France, an event restricted to diamond-frame bicycles. Two notable races that permit recumbent bicycles and streamliners are the Race Across Amer- ica and the World Human-Powered Speed Challenge. The Race Across America is one of the toughest races in the world. Competing individuals or teams start in California and race to New Jersey, with minimal sleep. The team record is slightly over 5 days for a faired recumbent bicycle, while the individual record is a little over 8 days. The World Human-Powered Speed Challenge held in Battle Moun- tain, Nevada, has hosted most of the land HPV speed records in recent years. On September 17, 2015, Todd Reichert set the men’s world record for the 200 meter flying start time trial with a speed of 137.9 kph1 (85.71 mph). This is quite remark- able, considering that top speeds for conventional racing bikes are usually under 50 kph (31 mph) and for recreational cyclists around 30 kph (19 mph). For vehicle engineers, racing is a means of validating and proving new designs and design modifications. Competitive cyclists tend to be strong and to ride frequently. They demand the best performance from each vehicle system and often ride vehicles to the limits of performance. Components and systems that continue to operate and function well throughout training and racing generally function well for many years of less rigorous use. In recent years, cycling compo- nent manufacturers have competed to develop better, lighter, race-worthy parts and systems. The most successful designs become top-tier components seen on the best competition vehicles. Lower-tier components benefit as the best tech- nologies trickle down through product lines. The bicycle or HPV consumer is the ultimate beneficiary of this process, as the quality of lower-end components has increased significantly over the last few years wit hout a concomitant increase in cost.

1IHPVA announcements, http://ihpva.org/home/, Accessed October 10, 2015.

Economics While the physical challenges and excitement of racing appeal to some, economics attracts more people to HPVs than perhaps any other reason. Human-powered vehicles, especially bicycles, are substantially less expensive to purchase, own, and operate than other vehicles. In the United States, a significant number of people with limited or no income use bicycles for transportation simply because they are affordable. This group includes students, of course, but it also includes many of our nation’s poor. It is not hard to find a rideable bicycle at a garage sale or thrift store for less than $25.00. What many people with incomes well above the poverty level do not realize is just how large transportation costs can be, particularly with a transportation infrastructure that favors personal automobiles. The cost differential can be calculated relatively easily. Consider a commuter that lives seven miles from her workplace. Additional driving brings her yearly average up to 15,000 miles. She bought the car after graduation from college for $18,000, paying $4,000 down and financing the rest at six% interest. On average, the car gets 22 miles per gallon, and her average price for fuel is $2.60. Maintenance costs her on average five cents per mile. She is more fortunate than many city workers, as she has free parking both at work and home. Including insurance at $350 per year, her total operating costs are very close to average, about 45 cents per mile. See Table 1-1 for more details and assumptions. She decides to investigate how much money she would save if she sold her car and bought a bicycle. Her bicycle would cost $1500, plus an additional $250 for clothing and accessories. She would spend about $725 each year on bicycle maintenance, sports foods and drinks, and accessories. Because she makes some long-distance trips that would not be practical for the bike, she spends about $400 per year on automobile rental. Since she rides regularly, she also cancelled her $216 gym membership. Annual cost for both car and bike are plotted in Figure 1-1. The first year, she would save over $8,000, primarily because of the large down payment on the car. During loan repayment, she would save over $5,900 per year, but after the loan is paid off, her annual savings is still almost $2000. Each year she places the savings in a certificate of deposit earning four percent interest. At the end of 10 years she would have over $50,000 in the bank thanks to her bicycle commute. The example is quite realistic, and the savings are realizable. In this case, the yearly savings is more than 12% of the United States median family income. For many people, this is a very significant amount. Different scenarios may result in different savings, but in virtually all cases, the savings are large. In some cases, the savings after 10 years can approach $100,000.

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Table 1-1 Data for cost comparison of bicycle and automobile

Input Variables Value Units Input Variables Value Units Initial Cost of Auto 18000 $ Initial cost of bike 1500 $ Cost accessories/ Financed amount 14000 $ clothing 250 $ Loan period 4 years Maintenance 150 $/year Interest 6 %APR Clothing maintenance 75 $/year Gas Mileage 22 MPG Auto rental (trips) 400 $/year Annual Miles driven 15000 miles Sports drinks/snacks 500 $/year Gasoline price 2.60 $/gal Gym Savings 216 $/year Insurance 350 $/year Sold at 10 years Maintenance 0.05 $/mile Salvage value 0 $ Sold at 10 years Salvage value 1500 $

Savings interest rate 4 %APR

Assumptions: Auto and bike replaced with identical vehicle Difference placed in savings Auto loan is paid off on schedule Bicycle is bought with cash Bicycle is not insured Notes: Auto rental covers transportations costs for trips that would be driven in auto only Annual bike mileage is usually less than comparable auto mileage Savings based on the entire difference placed in savings account

Fitness and Health Human-powered vehicles used on a regular basis can significantly improve health and fitness. Health problems related to sedentary lifestyles affect a significant portion of the world’s population. In 2006, Dr. Barry Popkin, in a presentation to the International Association of Agricultural Economists, announced that the number of overweight people around the globe exceeds the number of hungry people.2 This is particularly a problem in developed countries such as the United

2Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/4793455.stm Pub- lished: 2006/08/15 09:06:27 GMT, accessed 2007/08/20.

Figure 1-1 Cost comparison of bicycle and automobile

States. Sedentary lifestyles can lead to obesity, with many associated health risks including diabetes and cardiovascular disease. In contrast, regular physical activity can reduce the likelihood of obesity and increase overall health. Many people in the United States recognize the benefits of regular exercise. People who exercise regularly tend to live longer, more active lives. Regular aero- bic exercise keeps the cardiovascular system in good shape, prevents or reduces high blood pressure, and reduces levels of potentially harmful LDL cholesterol. Long-term regular exercise may also raise HDL (good) cholesterol levels. Moder- ate levels of exercise improve the immune system (although very intense exercise may actually impair immune system function.) Exercise also elevates mood and feelings. Brain levels of endorphins, serotonin, and dopamine are raised with either brief, intense exercise or longer, moderate exercise. These benefits have been shown to reduce the effects of depression and lead to improved feelings of well-being. Long-term exercise, coupled with a good diet, is effective for weight loss. Even brief, but regular, periods of exercise can be beneficial, and cycling is particularly effective. Generally, exercise does not make overweight people hungrier. Regular cycling or HPV use provides all of these health benefits. Gym memberships and fitness clubs are quite popular, and work well for many. Others, how- ever, find it difficult to make time for a workout, or drop out after a few sessions. Recreational bicycling or HPV riding is an enjoyable way to exercise, but—as with

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gym memberships—it can be difficult to make time for it. An excellent alternative is to use HPVs for commuting or errands around town. The incremental time required to complete a trip by HPV is much smaller than that required for an exercise program, and can be done on a daily basis. Some consider HPV transportation a means of getting time for free. If a commute takes 20 minutes by automobile and 50 minutes by HPV, the trip adds 30 minutes to the commute, but provides 50 minutes of exercise. Compared to spending an hour in the gym, this provides an extra 20 minutes per day. Using HPVs as transportation leads to a much healthier lifestyle than that of driving every trip. Counterintuitively, blood levels of toxins from automobile exhaust products are higher in motorists than in cyclists in the same environment—another health benefit of cycling. Bicycle and HPVs are also much safer than many people realize. Based on sta- tistics for fatal accidents, for every hour of operation a motorist is approximately twice as likely to die in an accident as a cyclist. By comparing on an hourly basis, compensation is made for the different number of miles traveled and the different speeds of automobiles and bicycles. The likely cause is the substantial difference in kinetic energies. A light car at 45 mph has about one hundred times the kinetic energy of a cyclist, while an SUV at interstate speeds has about a thousand times the energy. Most bicycle accidents are falls, in which the rider is not seriously injured. HPVs can be made even safer than bicycles. A long wheelbase recumbent bicycle with under-seat steering is perhaps the safest type of non-faired bicycle. The risk of a forward tip-over is negligible, and the energy of a frontal collision is absorbed by the bicycle and the rider’s legs (rather than his head). A fairing, or shell around the rider, can provide additional protection. Shells are used to reduce aerodynamic drag and to enclose vehicle systems which sometimes include rollover protection. A well designed shell will also provide protection against abrasions in the event of a fall. The safety advantage of enclosed HPVs was illustrated in 2003 when Sam Whittingham experienced a front tire blowout at 82 mph during a speed record attempt. He slid, spun, and went airborne before coming to rest 250 yards away. He was shaken, but walked away from the accident. It is quite possible to design everyday HPVs and velomobiles to be exceptionally safe. There is a well-established body of literature documenting the health benefits of cycling. Johan de Hartog3 and colleagues conducted a study in the Netherlands investigating the health benefits and risks of cycling as compared to car driving.

3Johan de Hartog, J., Boogaard, H., Nijland, H., and Hoek, G., 2010, “Do the Health Benefits of Cycling Outweigh the Risks?”,Environmental Health Perspectives, 118(8), 1109–1116.

They found that the beneficial effects of exercise exceeded the health risks due to both accidents and exposure to air pollution. Cyclists in general lived longer than car drivers. A number of other studies support the claimed health benefits of cycling.4,5 These studies indicate that the general perception in the United States that cycling is inherently dangerous is probably inaccurate.

Mobility Human-powered vehicles provide excellent mobility for local trips. Mobility is the ability to get to a destination in an efficient and relatively quick manner. Road HPVs are particularly adept at local trips in both rural and urban areas, with mobility sometimes approaching or exceeding that of motor vehicles. For example, in heavily congested areas, bicycles are often faster than automobiles. The bicycle messenger business exists primarily because of this fact. Mountain bicycles can provide outstanding mobility in areas without roads. Canoes and kayaks excel in waterways that other boats cannot navigate, such as shallow, rocky waters or waters choked with vegetation. They are also easily carried across portages, making them ideal for wilderness trips in regions with many lakes and rivers. The majority of automobile trips in the United States are short, and many trips are very short—less than one or two miles. Most of these trips could be completed by human-power with little or no lost time. In areas that have limited parking for automobiles and in congested areas, bicycles are much more convenient, often allowing the operator to ride right up to his or her destination.

Environment Environmental concerns provide a compelling reason to use human-powered vehicles. In the developed world, transportation systems account for a very significant fraction of air pollution. Emissions from motor vehicles include toxins and greenhouse gasses (GHGs.) In the United States, the prevalence of personal automobiles and the relatively low cost of motor fuel have led to a transportation infrastructure that is predominantly based on highway vehicles. These vehicles are generally inefficient, resulting in more pollution per passenger-mile than other transportation modes, such as rail. A second consequence is the rapid growth and

4Pucher, J., Dill, J., Handy, S., 2010, “Infrastructure, Programs, and Policies to Increase Bicycling: An International Review”, Preventive Medicine, 50, S106–S125. 5Yang, L., Sahlqvist, S., McMinn, A., Griffin, S. J., and Ogilvie, D., 2010, “Interventions to Promote Cycling: Systematic Review”, c5293, British Medical Journal, 341.

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development of suburban and rural areas. This has put increased pressure on wetlands and wildlife habitat, as well as encouraged longer commutes from home to workplace. The result is a combination of increased air pollution and decreased natural resources. Automobiles are also noisy, which can also be considered a type of pollution of the environment. Transportation accounts for a significant fraction of air pollution and greenhouse gas emissions in the United States. On-road mobile sources account for 51% of all carbon monoxide emissions, 29% of all hydrocarbon emissions, 34% of all nitrogen oxides, and 10% of all particulate emissions. Cars and motorcycles contribute more than half of the on-road mobile sources for carbon monoxide and hydrocarbons, while gasoline trucks and diesel vehicles account for most of the on-road nitrogen oxides and particulates. Emissions include combustion products and fuel evaporation. One third of the greenhouse gas emissions are produced by mobile sources. For every liter of gasoline burned, 2.3 kg of carbon dioxide equiv-

alents are released into the atmosphere (19.4 lb CO2E per US gallon burned). Greenhouse gas concentrations have risen sharply since the start of the industrial

Many scientists are concerned about the significant increase in the con-

centration of CO2 and other GHGs in the atmosphere. Since the preindustrial

era, atmospheric concentrations of CO2 have increased by nearly 30 percent

and CH4 concentrations have more than doubled. There is a growing international scientific consensus that this increase has been caused, at least in part, by human activity, primarily the burning of fossil fuels (coal, oil, and natural gas) for such activities as generating electricity and driving cars. Moreover, in international scientific circles a consensus is growing that

the buildup of CO2 and other GHGs in the atmosphere will lead to major environmental changes such as (1) rising sea levels that may flood coastal and river delta communities; (2) shrinking mountain glaciers and reduced snow cover that may diminish fresh water resources; (3) the spread of infectious diseases and increased heat-related mortality; (4) possible loss in biological diversity and other impacts on ecosystems; and (5) agricultural shifts such as impacts on crop yields and productivity. Although reliably detecting the trends in climate due to natural variability is difficult, the most accepted cur- rent projections suggest that the rate of climate change attributable to GHGs will far exceed any natural climate changes that have occurred during the last 1,000 years.

Figure 1-2 CO2 Production from typical cyclist on a city bike era, leading to increasing average global temperatures. The US EPA summarized the likely or possible environmental changes, some of which are already visible:6 Significantly increasing the number and use of human-powered vehicles used for transportation can alleviate the environmental damage from the transportation sector. This is a practical and effective solution that could be easily and quickly implemented. HPVs produce no pollutants during use, and a small fraction of the greenhouse gas emitted by automobiles. Figure 1-2 shows the greenhouse gas emissions of automobiles on a per-mile basis as a function of miles-per-gallon. The average automobile fuel mileage is about 22 mpg. The average automobile emits 418 grams of greenhouse gas every mile. An HPV driver exhales carbon dioxide, but in much smaller amounts. Carbon dioxide emissions for a typical city bicycle with a 77 kg rider are plotted as a function of speed in Figure 1-3. For a given trip, greenhouse gas emissions are reduced by about two orders of magnitude. Any alternative transportation system must not only reduce emissions, but must also be affordable and use existing technology. Bicycles and HPVs use existing infrastructure—roadways and bicycle paths—and would require no additional capital outlay. In fact, HPVs inflict less damage to roads than automobiles, so it is conceivable that infrastructure costs could actually decline with increased HPV

6SOLID WASTE MANAGEMENT AND GREENHOUSE GASES A Life-Cycle Assessment of Emissions and Sinks, 3rd EDITION, US EPA, September 2006.

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Figure 1-3 Greenhouse gas emissions from gasoline-powered motor vehicles

use. Cost to consumers could also be significantly reduced, as discussed above. Human-powered vehicles fill a unique role in sustainable transportation alternatives. No other option can provide quantifiable reduction in air pollutants and greenhouse gas emissions with available and affordable technology that uses existing infrastructure. HPVs are, for the present, critical to achieving a sustainable transportation system.