Question

In: Civil Engineering

Given: - Level terrain - extended freeway segment - Urban area with 0.9 interchanges/km - DDHV...

Given:

- Level terrain - extended freeway segment

- Urban area with 0.9 interchanges/km

- DDHV 4050 vehicles/hour

- 10% trucks, no buses, no RVs

- PHF 0.95

- Full shoulder and 3.6m wide lanes

Determine:

- Number of lanes to operate at LOS=C

Expert Solution

Assume Base free flow speed (BFFS) = 90 kmph

Lane width = 3.6 m

Reduction in speed corresponding to lane width, f_LW = 0 kmph

Lateral Clearance = 1.8 m

Reduction in speed corresponding to lateral clearance, f_LC kmph

Interchanges/Ramps = 0.9/km

Reduction in speed corresponding to Interchanges/ramps, f_ID = 8.1 kmph

No. of lanes in one direction = n

Reduction in speed corresponding to number of lanes, f_N kmph

Free Flow Speed (FFS) = BFFS – f_LW – f_LC – f_N – f_ID= 90 – 0 - 8.1 - f_LC – f_N kmph

Peak Flow, V = 4050 veh/hr

Peak-hour factor = 0.95

Trucks = 10 %

Level Terrain

f_HV = 1/ (1 + 0.10 (1.5-1)) = 1/1.05 = 0.952

f_P = 1.0

Peak Flow Rate, V_p = V / (PHV*n*f_HV*f_P) = 4050/ (0.95*n*0.952*1.0) = 4478.11/n ~ 4478/n veh/hr/ln

S = FFS

Density = V_p/S

Hence Level of Service is C

Density of LOS C should lie between 11 – 16 veh/km/ln

a) Assume 2 - lanes in each direction

FFS = 81.9 - 7.3 - 0 = 74.6 kmph

Flow rate = 4478/2 = 2239 veh/hr/ln

Density = 2239/74.6 = 30.03 veh/km/ln

Not possible

b) Assume 3 - lanes in each direction

FFS = 81.9 - 4.8 - 0 = 77.1 kmph

Flow rate = 4478/3 = 1493 veh/hr/ln

Density = 1493/77.1 = 19.36 veh/km/ln

Not possible

C) Assume 4 - lanes in each direction

FFS = 81.9 - 2.4 - 0 = 79.5 kmph

Flow rate = 4478/4 = 1120 veh/hr/ln

Density = 1120/79.5 = 14.08 veh/km/ln

Possible

Hence, Four- lanes in each direction should be considered to obtain LOS C

Total number of lanes = 8

Ally Wells answered 2 years ago

A long segment of the suburban freeway is to be designed on level terrain. The level...

A long segment of the suburban freeway is to be designed on level terrain. The level segment, however, is followed by a 4.5% grade, 2.0 miles in length. If the DDHV is 2,500 veh/h with 15% trucks (standard mix), how many lanes will be needed on the (a) upgrade, (b) downgrade, (c) level terrain segment to provide for the level of service C? Lane widths and lateral clearances may be assumed to be 12 ft and 6 ft, respectively. Ramp...

9) An existing rural freeway in level terrain is to be analyzed to determine LOS using...

9) An existing rural freeway in level terrain is to be analyzed to determine LOS using the following information: number of lanes in each direction equals 2, peak hour volume of 2140 veh/h (in the peak direction), 15% trucks, 2% recreational vehicles, PHF = 0.90, lane width = 12 ft, lateral clearance = 10 ft, average interchange spacing is 3 mi.

A six-lane freeway with three lanes in each direction is on a level terrain and has...

A six-lane freeway with three lanes in each direction is on a level terrain and has 11-ft lanes with a 4-ft right-side shoulder. The total ramp density is 2 ramps per mile. The directional peak-hour traffic volume is 5400 vehicles with a peak-hour factor of 0.95 and all familiar users. The traffic stream includes 5% trucks and another 5% buses and no recreational vehicles. The city has decided to ban all heavy vehicles from using the freeway during the peak...

A six lane urban freeway (three lanes in each direction) in mountainous terrain has 10-ft lanes...

A six lane urban freeway (three lanes in each direction) in mountainous terrain has 10-ft lanes and obstructions 5 ft from the right edge. For every mile of freeway, there is one interchange. The traffic stream consists of mostly commuters with a peak hour factor of 0.84, peak hour volume of 2500 vehicles, and 4% recreational vehicles. What is the LOS? Assume base free flow speed of 70 mph

A four-lane urban freeway is rolling on rolling terrain with 12-ft lanes, obstructions 2-ft from the...

A four-lane urban freeway is rolling on rolling terrain with 12-ft lanes, obstructions 2-ft from the right edge of the traveled pavement, and nine ramps within three miles upstream and three miles downstream of the midpoint of the analysis segment. The traffic stream consists primarily of commuters. A directional weekday peak-hour volume of 2400 vehicles is observed with 800 vehicles arriving in the most congested 15-min period. If the traffic stream has 10% large trucks and buses and recreational vehicles,...

6-lane freeway (3 lanes in each direction) in level terrain has a current one-directional volume of...

6-lane freeway (3 lanes in each direction) in level terrain has a current one-directional volume of 5000 veh/h; it is estimated that in 3 years, volume will have increased to 5600 veh/h. The traffic mix includes 10% trucks. The free-flow speed has been measured at 70 mph and the PHF is 0.95. a) Determine the current LOS. b) Determine the LOS in 3 years. c) After the initial three years, traffic grows at 4% per year, when will capacity be...