Quiz #4

[John QPE]

OK, I'll try one ... this will help me study

A (North/South) crosswalk is proposed across a 4-lane (East-West) roadway. All East-West travel lanes are 11-feet wide. A 10-foot wide grass median divides the roadway. The proposed crosswalk width is 12-feet wide. The median encroaches into the crosswalk 1 foot. The number of pedestrians crossing is 200 ped/hr. Cycle length is 120 seconds. Calculate the minimum green time for the proposed pedestrian crosswalk.

 

[ptatohed]

JQ, you make me proud! <sniff-sniff>.... need Kleenex.......

 

[John QPE]

56 views, and not 1 attempt?

I'll be back Monday ... come on, this isn't hard.

 

[ptatohed]

56 views, and not 1 attempt?

I'll be back Monday ... come on, this isn't hard.

lol, I passed it on to my 2 friends who are taking Civil/Transpo so I will let you know what they come up with.

 

[ptatohed]

Ok, my co-worker gets Gp = 17.0335 sec.

Is that correct?

Do we get 4 A - D choices?

 

[John QPE]

A. 17.03

B. 18.34

C. 18.20

D. 18.51

I'm using 4.0 fps as Sp

 

[ptatohed]

A. 17.03

B. 18.34

C. 18.20

D. 18.51

I'm using 4.0 fps as Sp

So you are saying A is not the answer?

 

[John QPE]

A is not correct (unless I did something wrong).

I'll post my solution since no one is biting.

 

[John QPE]

Gp = 3.2 + L/Sp + (2.7 Nped/We)

The effective crosswalk width is 11 ft (12' - 1') so we use this equation. There is a different equation for We </= 10'

So after we determine We, you must determine number of cycles, and Nped

3600 secs/120 secs/cyc = 30 cycles

200 peds/30 cyc = 6.67 peds/cyc

Then just plug n chug:

Gp = 3.2 + 54ft/4.0 ft/sec + (2.7 6.67/11 ft)

Gp = 18.34 seconds

 

[ptatohed]

Gp = 3.2 + L/Sp + (2.7 Nped/We)

The effective crosswalk width is 11 ft (12' - 1') so we use this equation. There is a different equation for We </= 10'

So after we determine We, you must determine number of cycles, and Nped

3600 secs/120 secs/cyc = 30 cycles

200 peds/30 cyc = 6.67 peds/cyc

Then just plug n chug:

Gp = 3.2 + 54ft/4.0 ft/sec + (2.7 6.67/11 ft)

Gp = 18.34 seconds

Yes, you are correct. My friend and I looked at it today at lunch. He was accidentally using L (54') where We (11') should be in the last denominator. Thanks JQ.

 

[John QPE]

Eggggggsellent!!