Tag Archives

Archive of posts published in the category: Worth
Apr
18

City of Fort Worth, Texas


Public Transportation

Trinity Metro

Public bus, carpool, vanpool and other public transportation services in Fort Worth and participating cities in greater Tarrant County.

ACCESS paratransit service

A service of Trinity Metro offering door-to-door transportation designed for the mobility impaired.

Trinity Railway Express (TRE)

Commuter rail service between downtown Fort Worth and downtown Dallas. This service is a partnership between Trinity Metro and Dallas Area Rapid Transit (DART).

Streets and Highways

West Seventh Street Safety Improvements

View accessibility improvements for the thriving West 7th Street neighborhood underway now.

City Transportation Projects

View city-funded transportation projects.

Texas Department of Transportation

The Texas Department of Transportation maintains state highways and interstates.

North Texas Tollway Authority (NTTA)

The NTTA constructs and maintains tollways in North Texas.

Interstate 35

Information about construction projects on Interstate 35.

North Tarrant Express

A focused reconstruction of I-820 and I-35W to improve traffic flow.

Bicycle Routes

Find current bike lanes and routes, and learn more about the effort to encourage bicycle commuting.

Parking

City-owned Parking and Meters

Find information on city-owned parking lots and meter information/rates.

FortWorthParking.com

Provided by Downtown Fort Worth Inc., Fort Worth Parking gives information on parking rates in the city’s most popular areas.

Resident-Only-Parking Program

Find out more about the city’s resident-only-parking program or apply for a permit.

Source Article

Apr
5

Are Expensive Bicycle Wheels Worth the Money? Let’s Check the Physics

In this video, you see a cyclist testing new aerodynamic wheels from Zipp. Swapping your wheels may seem like a small change, but can make a big difference. From his tests, the rider discovers:

  • With conventional wheels, he can ride 20 minutes at an average speed of 41.12 kph with an average power of 379 watts.
  • With the Zipp 808 NSW aero wheels he rides 51 minutes at an average speed of 41.13 kph and average power of 344 watts.

Before looking at power and energy, I should go over two small details.

First, how do you measure power? Cyclists can measure power by installing a small computer, called a power meter, that measures the input torque at the pedals or crankshaft and records the rotation angle at timed intervals. If you know the torque and angle, you can calculate the input energy. Dividing this energy by time gives you power.

La te xi t 1

Second, this isn’t a perfect test of aerodynamics. If you really want to examine the effect of the new wheels, you probably would have to put a bike with a dummy in a wind tunnel. When the reviewer takes his second ride, many things could have changed—wind, body position, amount of sweat on the body—and impacted performance. Let’s assume the only thing that changed was the wheels.

Air Drag and Power

What happens when you ride a bike? If you are moving at a constant speed, then the net force on the bike-human system must be zero. In a slightly simplified view, I can draw the following force diagram:

Spring 2016 Sketches key

The vertical forces (gravity pulling down and the ground pushing up) don’t really matter here. Just forget about them and pay attention to the horizontal forces. First, let’s look at the air drag. Air acts in complicated ways when an object passes through it. But who cares when we can make a simple model of air drag force? Here’s an expression for the magnitude of this force:

La te xi t 1

In this model, the air force is proportional to the square of the bike’s speed (v). For the other terms, we have:

  • ρ is the density of air (around 1.0 kg/m3).
  • A is the cross sectional area of the bike plus the rider (how much of the object interacts with the air).
  • Finally, C is the drag coefficient. This parameter depends upon the shape of the object. If you change the wheels, it is the value of C that should change.

The second horizontal force is the frictional force. An interaction between the road and the tires propels the bike. I know what you’re thinking: Doesn’t the human propel the bike? In a sense, yes. But the reality is sort of complicated. The rider’s power goes through the pedals and chain to the wheel, which turns. But the force comes from the tire pushing against the road. So for our energy perspective on this problem let’s just say the human provides the friction force.

Clearly the faster the biker