Blog Viewer

New Tools for Parking Design and Analysis - Questions and Answers

By Mr. Ransford McCourt P.E., PTOE posted 10-25-2011 05:02 PM

This space will be utilized to update participants of the New Tools for Parking Design and Analysis webinar October 25, 2011 of the questions they had at the webinar that were answered in the last 30 minutes.  Five questions were not answered and will be addressed here as will the all the questions - they will be attached.  Should participants have further questions, we can address them here.

One clarification - subtle - on the webinar quiz question #1: Design of traffic control for circulation in parking areas requires: a) an architect, b) an engineer, c) a city code, d) the MUTCD, e) the owner

Note that the reference to "circulation" here is to roadways in parking areas - it may be better worded "...circulation on parking area roadways requires...".  


Here is the question and answer material - add comments if you have further questions and I will periodically update via comments.

October 25, 2011 Parking Webinar Q & A Questions

Comment: In addition to your Huntington Beach city hall example, FedEx Field Football Stadium in Maryland just installed those solar car ports.

Q: Do you have any guidance on parking to prevent vehicle intrusion into buildings?

A:  When no curb is provided with disabled person parking spaces, the sign that restricts spaces can be placed on a durable pole or bollard – however, this has not emerged as a major issue.

Q: My limited experience, it seems like high LOS can equate with 2-way operations

A:  Two way can provide more flexibility for access.  One-way can confuses/frustrate some people and force trips to the front of buildings where more pedestrian conflicts are possible.  Angled parking and 1-way operation can be used to fit parking into odd spaces.   It is a site by site specific consideration

Q: Please define cross-aisles and design characteristics

A:  See slide 21 on your PPT copy for an example

Q: Is there a standard related to length of gate arms at parkade entrances?

A:  Not aware of that.  It is important to consider pedestrian exit (emergency or otherwise) to have space that is not fully blocked (also bike), but the gate needs to be effective in its access restriction task for motor vehicles.

Q: Can we get a copy of presentation including the  one with effects?

A:  You may download the PDF copy from  The actual .PPT not allowed due to copyright issues.

Q: Are any cities using the ITE Parking Generation Manual to determine site parking needs instead of standard codes of number of spaces per land use?

A:  First – Parking Generation is an Informational Report NOT a Manual.  Many agencies utilize Parking Generation as a tool in setting their code.  I am not aware of a city creating a nexus between the code and the data in Parking Generation.  Frankly, eliminating minimum parking codes and requiring the parking to be an element of site plan impact review may be a better approach to balance provision with need, while identifying possible impacts of intrusion as a site approval criteria (using Parking Generation for the demand analysis).

Q: Are there any recommendations or best practices for parking that is provided to the side or rear of buildings?  Our city code prevents most parking in front of retail buildings, but developers are often hesitant to comply

A:  Must follow your codes and how restrictive they are. There are lots of cases where parking is provided in front of buildings and you have to look specifically at your codes/vehicle requirements/emergency service provider preference (emphasis on the term preference).

Q: How do you display handicap vacancies in your parking garages with a display?

A:  Many garages do not address this.  At the Portland, OR Airport, their advance parking guidance system has LED signs above aisles with blue display numbers for disable person parking space availability.  Very possible to accommodate that in other settings.

Q: Are there any recommendations regarding the use of compact parking spaces?

A:  Look at your building codes. Good example of compact is the use of compact stalls by the perimeter for peak parking , retaining standard stalls closer to the building for routine use.  You have to look at your specific case in context.  Many designers (and users) prefer single space sizes.

Q: Is your presentation available to us to download?

A:  Download the PDF copy from

Q: How successful has parking space banking been?

A:  This has been used for sites that want the flexibility to add parking the future should conditions change (flex industrial building being used more as an office in a complying zone).

Q: What about the maximum grade in an interior parking?

A: Commonly garage parking areas are nearly flat.  Ramps can reach 15% as a typical maximum but these would not allow parking.  Sloped floor garages that allow parking on the slope ramps – typically ADA issues control in setting slopes not greater than 5% (above that door openings can be difficult – some are 5.5-6%).

Q: Can you please describe some of the best practices for express ramp gradients within parking structures, including slope transitions.

A:  Take grades you have and divide by 2 and blend in 12-20 foot area approach the full ramp slope.

Q: Are there any recommendations with regards to alternatives to impervious parking lots?  A:  A:  Lots of creative ideas out there today from pavers with large gaps, to use of plastics with gravel to porous pavement treatments

Q: Are Portland's minimum and maximum ratios used everywhere outside of downtown?

A:  Many surrounding cities adopted the Metro guidelines in their codes as part of Transportation System Plan updates.

Q: On page 12, Layout slide, it shows 340 - 450 sq ft per space yet you stated 350 as the upper limit - which is correct?

 A: The condition of 450 SF per space is for conditions where the parking is under a building with lots of columns penetrating the parking space.  The 350 SF per space is typical of an open layout for parking (surface lot or clear span structure).

Q: We are working in a jurisdiction taking a comprehensive look at re-doing our parking code.  We are referencing similar jurisdictions as well as ITE and ULI publications.  What should we be careful with in reference to the "averages" and "85th percentile" parking rates created in the ITE Handbook?

A:  This is a situation that requires context.  The average data might have relevance as a good minimum parking and the 85th percentile a good reference for maximum parking.  It really depends upon community interests – if parking intrusion is intolerable the higher levels are often important.  Where water quality, transportation demand management and land use are valued, the average number with justification for greater parking is an option.

Q: Really should mention automated parking that is a growing option in urban areas

A:  Robotic parking facilities have been around for decades and achieved little traction – primarily due to cost, operational issues and technology.  Today robotics are advanced enough, but cost and public perception can be issues.  Hoboken, NJ has an example of this application.

Q: When looking at park and ride or park and bike lots, what other considerations need to be taken into account other than sidewalks or bike lanes? when there is no main building destination

A:         Providing for bicycle access to transit platforms (bike lanes or cycle tracks or trails) are always good considerations.  The most significant issues are where trail heads require access of a site to connect to the public ROW – in these cases the parking areas need to consider appropriate treatments for bicycles to connect.

Q: What should the color of pavement markings be in parking lots?

A:  Color subject of debate. MUTCD requires white for on-street parking.  Some sites utilize yellow.  Others use unusual colors to designate employee parking from customer parking.  I would commonly encourage the use of white.

Q: Although pedestrians prefer to use the shortest path, please discuss barriers to redirect pedestrian activity.

A:  I am a huge fan of planning for pedestrian desire lines at the concept design level to address pedestrians needs as efficiently as possible and avoid the need for barriers entirely.

Q: Is it unwise to mix angle and 90 degree parking in the same surface lot?

A:  In the same row this was called the Drachman method - in general best practice would not include such a mix but if you are trying to squeeze out an extra parking then there are circumstances you could.  Keep in mind the aisle width should be design properly and issues of sight distance to address potential two-way use of the 90 degree half of the parking as compared to the angle part is important.

Q: What is the enforcement authority for signing and markings on private lots?

A:  For the roadways of private sites that use traffic control devices, the MUTCD should be reviewed.  There really is no enforcement authority beyond the site plan review process and potential for tort law to influence proper design.

Q: For bike parking and access cards, does that cause a trust factor (someone with access card has access to everyone’s bike) is an attendant necessary in these situations?

A:  State of the industry access cards allow the access to the bicycle enclosure/corral to be limited to the approved bicycle users – they can be uniquely identified.  Having an attendant is not necessary (but if the economy stays in a funk, maybe that is a jobs program).  I park my bicycle in a garage where the spaces are located near the cashier attendant – I feel that adds some security since they are present in the vicinity during the day – for design this is a good place to have bicycle spaces located.

Q: What are the parking design implications for electric vehicles (e.g. plug-ins)?

A:  Examples are solar carports similar to those noted earlier – these can use the solar power for the lighting and/or recharging.  In garages having spaces with recharge kiosks can be considered – there is little demand today and pricing of the charge is not well established presently.  Sacramento has downtown garage spaces with charging stations built in from the 1990s deployment of the EV1 – and now are available for today’s EVs.

Q: what would you classify as a service aisle do you have a design criteria?

A:  Aisle are the maneuvering area for vehicles between or adjacent to rows of parking spaces.  The widths of aisles are variable with the angle of parking – NPA’s Dimensions of Parking provides the best reference for this – 90 degree aisle are commonly 24-26 feet wide.  If this question was aimed at defined the width of a parking aisle to allow service vehicles to access loading docks – this requires turn templates to define the design vehicle needs – commonly a wider aisle and more generous turn radius.

Q: Is there a particular reference for parking lot layouts for fast food/drive in establishments?

A:  Parking layout is no different but the drive thru requires special consideration – McDonalds has corporate design criteria.

Q: Are there recommendations as to the location of public transit facilities in large parking lots, such as regional shopping centers?

A:  The fundamental here is getting transit patrons as close to their destinations as possible with the least motor vehicle conflicts.  Minimizing the bus transit travel on site is a good goal – for efficiency of the bus operation and the need for stronger pavement structure.

1 comment



11-16-2011 10:59 AM

Thanks for posting these Randy. I hope you found this tool easy to use.