Attachment E: Expert Critique of Costco's TIA Signature ... E.pdf · FIGURE 2: Parking Lots Near...

Attachment E: Expert Critique of Costco's TIA

Signature included in pdf version of Exhibit ____________________________________________________

Mark L. Franz, MSCE

of 11

January 13, 2012

TO: The Stop Costco Gas Coalition

3206 University Blvd. W.

Kensington, MD 20895

ATTN: Mr. Mark Adelman

FR: Mark L. Franz, MSCE

Ph.D. Candidate and Graduate Research Assistant

University of Maryland

Department of Civil & Environmental Engineering

1173 Glenn L. Martin Hall, Bldg #088

University of Maryland

College Park, MD 20742

RE: Review of the Costco Gas Station Traffic Impact Analysis (TIA) and Analysis of the

Associated Parking Situation at Westfield Wheaton Shopping Mall

This document provides a review of the TIA submitted by The Traffic Group

Consulting Firm for the proposed Costco Gas station at the Westfield Wheaton Mall. This

review includes investigation of the critical lane volume (CLV) analysis of intersections

in the immediate impact area of the proposed gas station. In addition, discussion on the

impact of parking and mixed-flow (pedestrian and vehicle) traffic safety is presented.

Summary of TIA Methodology

As required by the Montgomery County Department of Park and Planning Local Area

Transport Review (LATR) and Policy Area Mobility Review (PAMR) Guidelines, the Costco

Wholesale Corporation performed a TIA for their proposed development of a gas station. This

study included CLV analysis using standards defined in the LATR and PAMR Guidelines as

well as an evaluation of the impact of the development on pedestrian movements.

The methodology used for estimating the additional vehicular traffic in the submitted TIA

is called the four step model. The steps in this model include:

1. Trip Generation

2. Trip Distribution

3. Mode Choice

4. Route Assignment

In the trip generation step, the number of vehicular trips attracted to a given proposed

development is estimated. The developed trips are segregated into new trips, pass-by trips or

internal trips, with only new trips being added to the existing (or future) traffic conditions. These

estimations generally come from either nationally or locally calibrated field observations of

developments similar to that of the development of interest. In this step, it is required that all

other approved developments in the study area be considered as well.

of 11

The next step in the model, trip distribution, estimates where the trips generated by the

proposed development are coming from. Most typically, the percentages of the generated trips

are assumed to be correlated with demographic measures such as population density.

Subsequently, those trips must be assigned to a specific mode of transportation (bus, rail,

personal vehicle, etc.). However, in the case of a gas station it is assumed that all generated trips

will be made in personal vehicles. Lastly, generated trips must be assigned to a specific route. A

commonly used method for route assignment is equilibrium distribution, in which it is assumed

that road users will distribute themselves in a way such that travel times on the major routes to a

given development are equal. However, since the study area for this development has limited

route choices, this step appears to be omitted from the study. Upon completion of the four-step

model, the generated trips for all proposed developments in the study area must be added to the

existing traffic conditions. The performances of individual intersections in the impact area were

evaluated using the CLV method. The submitted TIA concludes by evaluating the pedestrian

demand, pedestrian signal timing and pedestrian crosswalks near the Westfield Wheaton Mall.

Review of TIA

The review of the TIA began by validating the existing traffic conditions at the

intersections included in the analysis area. This validation was performed comparing the

intersections turning movements presented in the TIA to data gathered by the Maryland State

Highway Administration (SHA, 2013). The results of this analysis show that the existing traffic

conditions in the TIA accurately reflect the conditions gathered by the SHA.

Next, the details of the four-step model were investigated. The TIA clearly shows the

basic calculations for trip generation using the peak-hour trip generation formulas in the Local

Area Transport Review (LATR) and Policy Area Mobility Review (PAMR) Guidelines

(Montgomery County Planning Department, 2008) and the Costco specific formulas described in

the submitted TIA. The number of new trips generated for the proposed gas station is made

conservative by reducing the number of internal trips from 52% to 30%. Thus, the methodology

used for the trip generation step is sound. In considering the trip distribution step, some minor

questions arise. While the TIA showed the trip distribution for each proposed development in the

study area, the basis of those distributions varies by development. It is not immediately clear

what the basis for these distributions were or why they have slight variations for certain

developments. In any case, since none of the analyzed intersections were close to the critical

CLV value, it is reasonable to assume that these variations in trip distribution would not cause

any intersection to reach its critical CLV value. As mentioned in the previous section of the

report, the mode choice and route assignment steps are justifiably simplified for the analysis area

and proposed development. Therefore, the results and conclusions presented in the TIA study

are sufficiently accurate in meeting the standards required in LATR and PAMR Guidelines.

Parking Analysis

While the submitted TIA adequately evaluated the impact of the proposed Costco gas

station on intersection performance and basic pedestrian considerations, it does not directly

address the impact of the gas station on parking at the Westfield Wheaton Shopping Mall. The

omission of this consideration may underestimate the impact of the proposed Costco gas station

on local traffic flow and traffic safety.

In a letter sent previously by the Kensington Height Civic Association to Ms. Susan

Scala-Demby of the Montgomery County Department of Permitting Services Zoning Division,

the citizens of the Kensington Heights neighborhood objected to a request made by Westfield

of 11

Inc. to reduce the required number of parking spaces at the Westfield Wheaton Shopping Mall.

In this request, Westfield Inc. asked the Department of Permitting Services to reduce the required

4.5 parking spaces per 1,000 square feet of retail space to 4.0 parking spaces per 1,000 square

feet of retail space. Interestingly, the requested parking rate of 4.0 spaces is lower than the

“effective parking rate” that was observed to be 4.2 parked vehicles per 1,000 square feet of

retail space during office hours.

The same request submitted by Westfield Inc. cited 1.466 million square feet of retail and

office space currently in use (at the time of the request). Using the standard Westfield Wheaton

parking rate of 4.5 parking spaces per 1,000 square feet of retail/office space, the required

parking is 6,597 spaces. The addition of the 54,000 square foot Costco Wholesale store would

increase the total retail area in the mall to 1.52 million square feet. Using the parking rate of 4.5

parking spaces per 1,000 square feet of retail space, the required number of parking stalls would

be raised to 6,840 spaces. If the “effective parking rate” of 4.2 spaces per 1,000 square feet of

retail is applied, the required parking spaces would total 6,384, while the requested rate of 4.0

parking spaces per 1,000 square feet of retail space would reduce the required parking spaces to

6,080. It is not clear if quoted square footage of retail space included the Dick’s Sporting Goods

store that opened in October of 2012 (after the request was submitted).

It was later stated at the testimony of Mr. Jim Agliata of Westfield Inc., that the Westfield

Wheaton Mall had 6,428 spaces available for its patrons. These spaces include 974 spaces in the

WMATA parking garage. However, it was not made clear that all of these spaces were actually

available to Westfield patrons, as some spaces may have been occupied by Metro users. To

address this concern, a simple parking study was conducted on Friday, January 11 at the

aforementioned WMATA parking garage. To show that some of the spaces in the garage may

not be available to Westfield Wheaton Mall patrons, parked cars were counted at 9am, one hour

before the mall opened. Thus, it is reasonable to assume that the vehicles parked in the WMATA

garage were not patrons of the mall. This study counted some 177 vehicles occupying spaces in

the garage. An image of the third level of the WMATA garage during the time of the study is

presented in Figure 1. While this count and image is not sufficient to estimate the “typical”

amount of spaces available spaces, it does show that at least some portion of the WMATA

garage will not be accessible by mall patrons. Therefore, the quoted 974 spaces may over-

estimate the actual amount of available parking space.

of 11

FIGURE 1: WMATA Parking Garage at 9am

In addition to the potential reduction in parking at the WMATA garage, Costco

Wholesale seeks to widen approximately 770 parking spaces from the current width of 9 feet to

10 feet. Assuming the widths of the existing driving lanes in the parking lot remain unchanged,

the widened parking stalls would eliminate some 77 parking spaces (presumably near the

Wholesale store entrance). The number of parking spaces would be further reduced (by about 92

spaces) with the construction of the proposed gas station. Thus, the original available parking

space count of 6,428 will be reduced by 169 spaces (to 6,259 spaces) by the widening of the

parking spaces and the footprint of the gas station. Note that this reduction does not include the

spaces not available to mall patrons in the WMATA garage. Therefore, if the requested rate of

4.0 parking spaces per 1,000 feet of retail space is used (resulting in 6,080 required spaces) this

leaves a surplus of 179 spaces. However, if more than 179 spaces in the WMATA garage are not

accessible to mall patrons, then even the requested rate of 4.0 parking spaces per 1,000 feet of

retail space will not provide sufficient parking spaces.

In addition to the general parking issues mentioned on the basis of parking spaces

provided per square footage of retail space, more specific parking concerns arise from the

inherent characteristics of the already built Costco Wholesale Store. While the using the square

footage method to estimate the required number of spaces required for the entire mall, this

methodology fails to take into account the proximity of available parking spaces to stores of

interest. In the instance of a wholesale store, it is reasonable to assume that most patrons will not

be willing to push their carts over far distances to load their vehicles. Thus, if the number of

available parking stalls near the main store exit is not sufficient, patrons may circulate the lot

looking for parking. This circulation of traffic raises the likelihood of a conflict, be it a vehicle-

to-vehicle or vehicle-to-pedestrian conflict. The lots nearest the main exit of the Costco store are

presented in Figure 2. For ease of reference, Lot A is defined to be the lot adjacent to Target and

the Costco Wholesale store. Lot B is defined to be the parking lot adjacent to the Macy’s and

Target stores.

of 11

FIGURE 2: Parking Lots Near Costco (Map Source, Google Maps, 2013)

To evaluate the current parking situation at Lots A and B, a basic parking inventory was

conducted via photographs. Figures 3-5 show the conditions in Lots A and B, respectively, on

Friday Jan. 11, 2013 at 2pm. Figures 6-9 show the same lots on Saturday Jan. 12, 2013.

Lot

B

Lot

A

of 11

FIGURE 3: Lot B on Friday Jan. 11 at 2pm

FIGURE 4: Portion of Lot A on Friday Jan. 11 at 2pm

of 11

FIGURE 5: Portion of Lot A on Friday Jan. 11 at 2pm

FIGURE 6: Lot B on Saturday Jan. 12 at 3pm

of 11

FIGURE 7: Portion of Lot A on Saturday Jan. 12 at 2pm


of 11


As depicted in Figures 3 and 6, Lot B was at it capacity on both dates. In fact, figure 6

shows at least one vehicle illegally parked. The scenario in Lot A shows that while this lot was

not near capacity, a significant portion of this lot is already being used by mall patrons (Figures

4,5,7 and 8). Figure 9 shows that the southern portion of Lot A was nearly empty. However, it

should be noted that the Costco Wholesale Store has not been opened. Thus, the 200 some new

evening trips attracted by Costco will have to compete for the remaining spaces. To exacerbate

the parking situation, the construction of the proposed gas station would have removed an

additional 92 spaces near the main exit of the Costco Wholesale Store.

While the photographs show the parking scenario on one weekend, there is no apparent

reason to believe the depicted situation is atypical. However, it is suggested that more studies be

conducted to better define the parking demand in these lots. It is worth noting that the month of

January tends to be the lowest month in terms of retail sales. This finding is supported by Figure

10, which shows monthly retail and food service trends for Jan. 2010-Oct. 2012 (US Census,

2013). Assuming Westfield Wheaton Mall follows this nation trend, the figures above may

depict a low demand environment at the mall in not peak season.

of 11

References

Google Maps. Westfield Wheaton Mall. Google. 2012.

Maryland State Highway Administration. Internet Traffic Monitoring System. Accessed

1/11/2013: http://shagbhisdadt.mdot.state.md.us/ITMS_Public/default.aspx

Montgomery County Planning Department. Local Area Transport Review (LATR) and Policy

Area Mobility Review (PAMR) Guidelines. Silver Spring, MD. 2008.

U.S. Census Bureau. Monthly and Annual Retail Trade. Washington D.C. 2013. Accessed on

1/12/2013: http://www.census.gov/retail/

Mark Franz | Page 1 of 2

Mark L. Franz

1904B Kermit Rd. • Silver Spring , MD 20910 • 724-413-0169 • [email protected]

Education and Qualifications:

Ph. D. Civil Engineering

University of Maryland, College Park, MD

Expected Graduation Spring 2013

Cumulative GPA 4.0/4.0

Engineer In Training

December 2011

M.S. Civil Engineering

West Virginia University, Morgantown, WV

Graduated August 2009


B.S. Astronomy Cum Laude

B.A. Physics Cum Laude

University of Florida, Gainesville, FL

Graduated June 2006


Experience:

University of Maryland, College Park, MD

Graduate Research Assistant and Lab Manager……………………………………………...................1/10 – Present

Researching the following topics:

o Evaluation of automated speed enforcement in Maryland work zones

o Real-time travel time estimation using Intelligent Transportation System (ITS) technology

o Analysis and prediction of freeway incident duration

o Dynamic dilemma zone protection system design and evaluation

o Applications of variable speed limits in recurrent congestion

Organizing meetings with collaboration partners such as consulting firms and Maryland

State Highway Administration

Assisting in research account oversight

Independent Traffic Consultant, College Park, MD

Traffic Engineering Consultant……………………………………………………………………….08/12 – Present

Performed and reviewed traffic impact studies for proposed developments in the greater Washington D.C.

metropolitan region

West Virginia Local Technical Assistance Program, West Virginia University, Morgantown, WV

Graduate Technical Assistant……………………………………………................................................... 8/07 – 8/09

Developed training material for road agency audiences by researching industry standards

including but not limited to: the Manual on Uniform Traffic Control Devices (MUTCD),

American Association of State Highway and Transportation Officials (AASHTO) Green

Book, Occupational Safety and Health Administration (OSHA) Standards and American

National Standards Institute (ANSI) Standards

Performed on site visits for West Virginia municipalities to resolve transportation issues

Produced technical assistance reports by analyzing field data and by providing

suggestions for improvement

Analyzed data and provided recommendations to improve transportation system issues

for low income communities with the West Virginia University Community Design

Team

mailto:[email protected]

Mark Franz | Page 2 of 2

Dr. Ron Eck, Ph.D., P.E., Engineering Consultant (Specializing in motorized and non-motorized

incident reconstruction), Morgantown, WV

Field Assistant……………………………………………………………………………………….……12/07 – 8/09

Performed slide to stop, sight distance, and crush measurement calculations for tort

liability claims

Activities:

ITS Maryland Student Member…………………………………………………………………..…..…9/09 – Present

Chi Epsilon National Civil Engineering Honor Society Member……………………………….……..4/09 – Present

Golden Key International Honour Society Member…………………………………...………….…..10/08 – Present

President ITS America, University of Maryland Chapter………………………….……………………..9/10 –10/11

Vice President ITS America, University of Maryland Chapter……………………..…………..…….…..9/09 – 9/10

Institute of Transportation Engineers Member………………………………........................................10/07–10/08

National Local Technical Assistance Program National Conference………………………..…………..7/07 and 7/08

Honors:

Engineer in Training……………………………………..………………………………………….…...12/11-Present

Mid-Atlantic Universities Transportation Center Fellowship…………………………………….…… 8/12-Present

UMD CEE Department Fellowship………………………………………………………………………………..8/11

A. James Clark (AJC) Fellowship Recipient………………………………….…………………………………..8/09

University of Florida Dean’s List…………………………………………………………………………….8/03-4/06

University of Florida Presidential Dinner for Outstanding Students………………………...............................4/05

Publications & Technical Papers:

Franz, M. Application of Variable Speed Limits in Recurrent Congestion. Ph.D Dissertation. University of

Maryland, USA. Working Paper.

Chang, G.L., Peng, C., and Franz, M. A Review of Pedestrian-Vehicle Interactions at Urban Intersections. Working

Paper.

Lu, Y. Park, S.Y., Franz, M.,Yang, X. and Chang, G.L. Improving Traffic Safety At Rail Grade Crossings: A Case

Study In Taiwan. Working Paper.

Chang, G.L., Liu, Y., Franz, M., Lu, Y., and Tao, R. ITS Application: Design and Evaluation of an Intelligent

Dilemma Zone Protection System for a High Speed Rural Intersection. Transportation Research Board 92nd

Annual

Meeting. Washington, D.C. 2013.

Franz, M., and Chang, G.L. Effects of Automated Speed Enforcement in Maryland Work Zones. Transportation

Research Board 90th Annual Meeting. Washington, D.C. 2011.

Kim, W., Franz, M., and Chang, G.L. Enhancement of Freeway Incident Traffic Management (FITM) and

Resulting Benefits. Maryland State Highway Research Report. Report No. MD-11- SP009B4Q. Baltimore, MD.

April 2012.

Franz, M.L. Local Agency Traffic Sign Retroreflectivity Case Study and Model of Observed Traffic Sign Light

Intensity. Master’s Thesis. West Virginia University, U.S. 2009.

References Available Upon Request

Attachment 1

Page | 1

February 23, 2013

FR: Mark L. Franz, MSCE Ph.D. Candidate and Graduate Research Assistant

University of Maryland Department of Civil & Environmental Engineering

1173 Glenn L. Martin Hall, Bldg #088 University of Maryland College Park, MD 20742

TO: Ms. Francoise Carrier Planning Board Chair Planning Board M-NCPPC 8787 Georgia Ave. Silver Spring, MD 20910

RE: Opposition to Special Exception Request S-2863, Costco Wholesale Corporation Dear Ms. Carrier and Members of the Planning Board, Thank you for the opportunity to testify in opposition to Special Exception Request S-2863. My name is Mark Franz; I have a Master’s Degree in Civil Engineering and am currently a Ph.D. Candidate and Graduate Research Assistant at the University of Maryland Department of Civil and Environmental Engineering. I anticipate graduating with my Ph.D. later this summer. The details of my credentials can be found in my previous filing: attachment 18B of the Planning Staff Report.

I feel that the passing of Special Exception Request S-2863 may adversely affect the traffic flow and safety of patrons of the Westfield Wheaton Mall, especially if the proposed gas station is sited as proposed in S-2863. Though the topics of traffic flow and safety are summarized in the Traffic Impact Analysis submitted by the Costco Wholesale Corporation several issues related to the potential impact of the proposed gas station were not addressed. While the generalized parking studies show that Westfield will provide ample parking for its patrons, the analysis appears to overlook the parking and internal traffic flow in the immediate vicinity of the Costco Wholesale store. The parking environment near a wholesale store is inherently different from that of a retail shopping center. Due to the nature of bulk goods purchases at wholesale stores, most patrons will seek to use the nearest parking spaces. Therefore, if these spaces are not available patrons will choose to either park at a space far from the entrances/exits, circulate the nearby spaces until one becomes available or decide to shop at another time or place. From a traffic flow and safety perspective, circulating vehicles and longer walking distances for pedestrians will increase the likelihood of an incident, whether it be between vehicles or between a vehicle and a pedestrian(s). This situation will be exacerbated by the additional traffic flow associated with the proposed gas station. Recognizing that the Costco Wholesale Store has already been built, measures should be taken to preserve a parking environment that will promote efficient traffic flow and safety of Westfield Mall patrons. With these considerations in mind, it seems the construction of the proposed Costco Gas Station may

Page | 2

compromise efficient flow of traffic and the safety of mall patrons. Therefore, I urge the Planning Board to deny Special Exception Request S-2863. The foundation of this argument is provided below:

Support for the Westfield Wheaton Mall request for reduced parking standards were based on parking spaces provided on the entire Westfield Wheaton Mall property (as reported in the Justification Statement for Westfield Wheaton Parking Waiver). While this methodology is useful in general planning decisions, it has the potential to overlook critical details related to parking, traffic flow and safety. For instance, the current available parking space count includes 974 spaces in the Washington Metropolitan Area Transit Authority (WMATA) garage. However, a parking count on the date of Friday, January 11, 2013 at 9AM revealed that 177 vehicles were parked in the WMATA garage (as reported in Attachment 18B of the Planning Staff Report). It is reasonable to assume that these vehicles were not patrons of the mall as the mall had not yet opened to the public. While this count may or may not reflect the parking conditions on a typical day, it does show that there is at least some reduction in amount of available parking spaces in this garage. The omission of such details may inaccurately report the actual number of available parking spaces for mall patrons.

In addition to the potential concerns with the general parking evaluation, more specific issues remain to be addressed in relation to the parking environment near a wholesale store. Due to the nature of the bulk goods purchases at a wholesale store such as Costco, many of the purchased goods require transport in a cart from the store to the patron’s personal vehicle. This observation makes parking spaces far from the store exit less attractive. Thus, it is unlikely that customers of Costco will be willing to park in lots that are not immediately adjacent to the primary access points of the Costco Storefront. The Costco Wholesale Store at the Westfield Wheaton Mall has two primary access points to nearby parking lots (labeled A and B in Figure 1). Access point A offers parking at the same grade as the store entrance. Access point B provides parking via a multi-level parking garage with a pedestrian bridge to access the mall and the Costco Store. Some additional parking is provided beneath the footprint of the Costco Store.

Page | 3

Figure 1: Primary Parking Access to Costco Wholesale Store (Google Maps, 2013)

As noted in documents previously submitted to Planning Staff, the parking lot adjacent to access point A (Figure 1) is shared by patrons of Target, Panera Bread and Elevation Burger (in addition to general Mall access). A site visit to this lot on the dates of Friday, January 11 and Saturday, January 12 revealed that this lot was approximately 30% full, this before the Costco store had opened (originally presented in Attachment 18B in the Planning Staff Report). Additional parking for potential Costco Wholesale customers may be offered in the parking garage near access point B (Figure 1) and the spaces under the Costco store. However, there are concerns in how well the parking spaces that are on a different level from the wholesale store will be utilized. While these spaces may reduce the physical distance between the store access point and offered parking spaces, the parking spaces on a level other than that of the access point would require patrons to use an elevator or specialized escalator to transport purchased goods. It is not clear in the Traffic Impact Analysis if Costco has built a store with parking provided in a multi-level garage to assess how patrons utilize such a parking facility. In any case, some patrons may find this inconvenient and could potentially reduce the use of such parking spaces. Given the aforementioned considerations, Costco patrons will likely seek to park as close as possible to store access points. As these spaces become full, patrons will choose to either park at a space far from the entrances/exits, circulate the nearby spaces until one becomes available or decide to not shop at that time. Considering that both the wholesale store and proposed gas station require membership, patrons may be less willing to take their business elsewhere. From a traffic flow and safety perspective, circulating vehicles and longer walking distances for pedestrians will increase the likelihood of an incident, whether it be between vehicles or between a vehicle and a pedestrian(s). Parking facilities should be designed to provide safe and efficient flow of both vehicles and pedestrians. Therefore, measures should be taken to minimize the potential conflicts for all facility users (i.e. pedestrians and motorists). With these concerns in mind, it seems the foot print of the proposed Costco Gas Station would consume precious

A B

Gas

Page | 4

parking spaces in the immediate vicinity of one of the Costco Wholesale Store entrances/exits. Moreover, the proposed gas station will increase internal traffic flow in parking lots near the wholesale store entrance. In doing so, the efficient flow of traffic and safety of mall patrons may be compromised by the construction of the proposed gas station.

In light of the parking and internal traffic flow issues mentioned above, the reduced parking standard and associated construction of the Costco Gas Station is not recommended. Therefore, I urge the Planning Board to deny Special Exception Request S-2863.

Thank you for considering my testimony. Sincerely,

Mark L. Franz, MSCE

Attachment 2

Page | 1

March 25, 2013

TO: The Stop Costco Gas Coalition

3206 University Blvd. W. Kensington, MD 20895

ATTN: Mr. Mark Adelman

FR: Mark L. Franz, MSCE Ph.D. Candidate and Graduate Research Assistant University of Maryland Department of Civil & Environmental Engineering

1173 Glenn L. Martin Hall, Bldg #088 University of Maryland College Park, MD 20742

RE: Traffic Impact Analysis Inquiry

The following document provides responses to questions raised by Mr. Mark Adelman of the Stop Costco Gas Coalition regarding the details of the Traffic Impact Analysis submitted in association with the proposed Costco Gas Station. The document includes the inquiries in their original form. My responses are provided in bold text.

1. I want to be as clear as possible about the Scoping Agreement. It went through a couple of stages, and I believe all the documents are included as attachments to Costco's filings (Exhibits P1 and P2), which are still available on our website. The fundamental question is whether there is anything about the Scoping Agreement that is either (a) unusual given how MoCo does such things or (b) unusual as to "best practices" nationwide. I was asking this question in a very narrow sense when I asked you (previously) about the exclusion of non-signalized intersections from the scoping agreement. Your answer to the more generic question could include your earlier answer about the non-signalized intersections. Please keep in mind that the County Code requires that the proposed land use not create a nuisance to the neighborhood by virtue of, inter alia, traffic. The Code is also posted to our website.

The scope of a traffic impact analysis (TIA) often depends on what is required by the planning agency overseeing the study. This decision may be affected by the size of the study area and expected traffic flow on the local network. In Attachment 18B of the Planning Staff Report, the basics process of a TIA was described. In the final step of the four step model, generated traffic must be assigned to a route. Here, it is common to use equilibrium assignment in which the planner assumes motorists will seek to utilize the shortest path (in terms of travel time) to their destination. Using this strategy, motorists will not deviate from the primary route(s) until a level of congestion is reached in which a secondary route

Page | 2

becomes the shortest time path to the final destination. Traffic will then distribute itself such that the travel time on each route is equal.

Montgomery County uses Critical Lane Volume (CLV) analysis for evaluating the impact of proposed developments. It is worth noting that Montgomery County uses a failing CLV value of 1800 veh/hr near Metro stations, while the failing value used by the Maryland State Highway Administration is 1600veh/hr. In any case, the CLV analysis of the major intersections in the study area showed that none of the intersections are close to 1600 veh/hr, let alone 1800 veh/hr. It is important to realize that while CLV analysis does not directly estimate travel times or delay, there is some correlation. Based on the reported CLV values it does not appear that the traffic generated by the developments included in the TIA will cause a level of delay that would alter their paths. Thus, Montgomery County may not have required the analysis of any non-signalized intersections.

2. The Costco store is of course still not open (we all predict it will not open on April 10 as was announced). It was listed as Background Development 8 (page 17 of P1). I find the trip generation numbers rather small. For comparison, take a look at the numbers for Background Development 6; this is a small branch bank (BB&T), for which the projections are about one half to one tenth that for the Costco store. Do the numbers for the Costco store make sense to you?

General guidance on trip generation is provided by an organization called the Institute of Transportation Engineers (ITE). It is worth noting that these rates are based on national averages and are provided for generalized developments. However, use of locally calibrated trip generation rates may be used for more accurate estimates. The trips generated by the bank were derived from the most recent edition of the ITE Trip Generation Manual (based on square footage). As for the Costco Wholesale Store, the products and services offered appear to comprise a unique type of development (offering vehicle tire services, groceries, clothing, electronics, etc.) that may not be adequately represented by the “common” developments provided in the ITE Trip Generation Manual. Additionally, having such a facility under one roof may generate a different trip rate than the sum of the independent trip rates for similar developments. The trip generation rates for the Costco store were based on field calibrated studies of similar Costco developments. Without knowing the details of the trip generation/calibration study, I can neither confirm nor deny the accuracy of these rates. However, it appears that these rates have been deemed as reliable by the Montgomery County Planning Board as well as by planners in Pennsylvania. 3. I have asked you about the various "maps" that project, for each background development, how the traffic generated by the development will reach - and pass by - the area. Having looked at these again, I am even more concerned that certain "questions" are not really answered. Take

Page | 3

a look at the one for the store and for the gas station. Note that the one for the store does NOT have those percentage numbers (white numbers in black circles) that are found in other maps. Any idea why not? I believe you are referring to the trip assignment figures in the TIA document, submitted on October 18, 2012. The trip assignment for the Costco store and approved retail space with the mall (Development #8) are provided in Appendix C (Exhibit-P2 on the Stop Costco Gas Coalition website). The trip assignment figure for the proposed Costco Gas Station (Development #9) can be located on page 23 of the TIA (Exhibit-P1 on the Stop Costco Gas Coalition website). The figures following both of the aforementioned figures are the pass-by trip assignment for each respective development. These figures do not have the percentage numbers, as the pass by trip turning movements are shown at each intersection.

As to all these maps, the aspect of them that concerns me is that none address the fundamental (for me/us) question as to how the traffic, after reaching the area, will "partition" itself into the various entrances to the mall. Take a look at maps 6, 7, and 9A (all developments, background, and gas station respectively). They all make assumptions about how traffic coming to the area will enter the Mall via the entrances off University. How the proportioning was done is NOT spelled out anywhere that I can find and the numbers make no sense to me. Let me give you one example of my reasoning and then you can either point out how I am wrong, or clarify how the numbers in Costco's TIA are fairly reasonable.

Yes, I also noticed how the proportions for the trip distribution change for each development. Again, without the details of how these percentages were generated, I can neither confirm nor deny the accuracy of these numbers. Often, some measure of population or population density is used to develop the trip distribution. However, the proximity of similar developments will also affect the trip distribution patterns. For example, if a new grocery store is developed 2 miles north of an existing grocery store, than trips from the south may be relatively lower than those from other directions. Again, it is not clear if such methodology was used in this TIA. In any case, these numbers are estimates of where the newly generated trips will be coming from for each development. Map 9A implies that about 20% of the traffic coming to buy gas will come from the south and southwest. That seems low to me. The map also implies that about 60% will come from the north, northeast and east and that cars coming from that direction will distribute themselves to the entrances off Viers Mill and University more or less evenly. But that seems unreasonable to me. Viers Mill is already more heavily congested than University; cars do not tend to continue on Viers Mill to reach (e.g. Giant) stores close to University. They tend to use University to reach Giant, and it seems to me that they will do the same in order to reach Costco. I agree with your point here. For patrons coming from the Northwest, accessing the Costco store and gas station will be easier from University Blvd rather than from Viers Mill Road.

Page | 4

It seems that the Costco store trip assignment does indeed have some of those patrons making the right turn from southbound Viers Mill Road on to University Blvd, while the gas station has all of its patrons continuing on Viers Mill Road. Again, without knowing the details of the route assignment calculations I cannot explain exactly why this methodology is used. In any case, the trips generated by the gas station are relatively small compared to that of the other developments. Therefore, these anomalies in the route assignment step would not appear to change the conclusion of acceptable CLV values for the intersections in the analysis zone. Even more problematic from my point of view is the set of numbers in Exhibits 11A and 11B. I am focussing on lines 4 and 5 (the turns at Valley View and East Ave.) My point is that no one traveling on University (from either direction) will use East Ave. to reach the Costco gas station OR store. They will use Valley View. To do otherwise would mean going PAST Valley View, entering the Mall via East, then reversing course and going back towards the intersection of Valley View with the ring road, which makes no sense. The reason I am focussing on this apparently minor point is that I know that the Valley View/Ring Road intersection currently experiences episodic congestion and that this can only get worse once the store is open (and worse still if the gas station opens). I can of course say just this when I testify, but I would prefer to know what you think about this - as a professional - rather than just state it as my "assertion". If you think - as a professional - that I am wrong, please tell me. If you find a professional way to state my assertion, please tell me. I agree that having any eastbound traffic pass the Valley View Avenue intersection to use the Eastern Avenue intersection to access the Costco development does not seem reasonable. However, keep in mind that development #8 is the Costco store and other retail in the mall. Looking at the trip assignment for development #8, the small amount of turns occurring at Eastern Ave is likely associated with the trips generated by the other developments within the mall. Additionally, the trip assignment for the gas station shows the new trips will add only to the Westbound University Blvd through movement and right turn from Eastern Ave onto University Blvd. This seems reasonable as the Westbound University Blvd through movement seems to be associated with vehicles accessing the gas station, while the right turn from Eastern Ave onto University Blvd is associated with patrons leaving the gas station.

4. Finally, I am concerned about my perception that local/state governments use TIAs to provide numbers that are as realistic as possible but that by setting the maximal values for CLVs (1800 and 1600 in this case), they essentially assure that no project will fail the TIA test. And that by NOT stipulating when a project is getting "too close" to the CLV number, they are making sure that there are no guidelines as to the "grey area" where the projections raise concerns but there are no "rules" as to what should be done. I would like your professional judgement on this. Am I simply off base? Is this something that professionals think about? If so, how do they suggest the numbers be used to make practical decisions?

Page | 5

In performing traffic impact studies, there are two general methodologies that are used, CLV and the Highway Capacity Manual (HCM). Both have their advantages and disadvantages. CLV was originally developed to explain intersection performance to non-traffic experts. However, the idea has taken on more rigorous analysis methods and is now accepted as a legitimate intersection performance planning tool. On the other hand, the HCM method requires more expertise in both the calculations and interpretation of the results. Both methods are accepted and used in practice.

The standard definition of a failing intersection in the CLV method is 1600 veh/hr. However, Montgomery County uses a value of 1800 veh/hr as the failing CLV value near metro stations. The reasoning for this elevated value is that alternative modes (i.e. transit) are available for those who desire to avoid road congestion (Local Area Transport Review and Policy Area Mobility Review Guidelines, 2008). However, this reasoning assumes that the alternative modes are perceived as safe, efficient, affordable and convenient for its potential users. Additionally, it is not clear why the value of 1800 veh/hr is used. For instance, why is this value not 1700 veh/hr or 2000 veh/hr? Usually, deviation from a standard (i.e. 1600 veh/hr) is supported by an engineering study. It is not clear if such a study was conducted to justify this value.

In any case, the use of 1800 veh/hr as the definition of a failing intersection does not affect the conclusions for this TIA, as none of the intersections exceeded the 1600 veh/hr CLV value.

This document was produced by,

Mark L. Franz, MSCE

Attachment E: Expert Critique of Costco's TIA Signature ... E.pdf · FIGURE 2: Parking Lots Near...

Documents

Transcript of Attachment E: Expert Critique of Costco's TIA Signature ... E.pdf · FIGURE 2: Parking Lots Near...