HomeMy WebLinkAboutCT 02-28; La Costa Condominiums; Tentative Map (CT) (36)Hofman Planning
Associates
Planning Fiscal Services Ewironmental
April 6,2004
Bob Johnson
City of Carlsbad Engineering Department
1635 Faraday Avenue
Carlsbad, CA 92008
SUBJECT: La Costa Condominiums - Justification and Alternatives for Lane Configurations
Dear Mr. Johnson:
As requested, the following information is intended to serve as justification for the right turn lane and
deceleration lane configurations shown in the attached exhibits. Sam Kab of Urban Systems, who is the
project traffic consultant, submitted this information. I have also included an analysis of the alternatives
that depicts the pros and cons of each scenario.
Right Turn Lane
Two primary criteria were used to determine the appropriate length for a right turn lane:
9 A right turn lane should be long enough to accommodate 1’ of stacking distance for every vehicle
entering during peak hour (this standard was taken from the Highway Capacity Manual Chart)
OR 9 The lane should be 150’ in length, which is the typical standard for low-volume turns.
We elected to use 150’, which is the more restrictive of the two options.
Deceleration Lane
The length of the deceleration lane was determined by using the Caltrans Table that calculates lane length
based on street speed.
Please review the attached exhibits and feel free to contact me with any questions.
Sincerely,
c/ Bill Hofman
CC: Saima Qureshy
BH:PC
Attachments
5900 Pasteur Court Suite 150 Carlsbad CA 92008 (760) 438-1465 Fax: (760) 438-2443
La Costa Condominiums - Alternative Analysis
The following is a list of pros and cons for the right tun lane, deceleration lane and traffic signal
alternatives prepared for the La Costa Condominiums project.
Right Turn Lane
Pros:
3 Provides a safer turn into the project through the use of a separate lane.
Cons:
3 Does not increase the line of site distance. > Increases retaining walls along the slope, which will not be as aesthetically pleasing.
3 Increases pavement and reduces landscaped area.
3 More expensive to construct than the existing plan.
3 Does not provide the speed reduction equivalent of the deceleration lane alternative.
Deceleration Lane
Pros:
3 Provides a safer turn into the project through the use of a separate lane.
Cons:
3 Does not increase the line of site distance.
P Increases retaining walls along the slope, which will not be as aesthetically pleasing.
3 Increases pavement and reduces landscaped area.
3 More expensive to construct than the existing plan.
Traffic Signal
Pros:
3 Controls the traffic flow and speed of cars along La Costa Avenue.
Cons:
3 Difficult to design based on corresponding driveway locations (driveways are not
aligned with project entrance).
9 More preferable to place signal at public intersection.
3 Neighbors will be affected by flashing lights.
3 Poles and mast arm located on residential street corner will be an intrusion and will
affect the aesthetics of the area.