Over the Edge - ITE Western District...• Land banking for possible new town sometime in the future • Local jobs, % retirees, etc. are unknowable • Lacking better data, but distance

(formerly Parsons Brinckerhoff)

Over the Edge

Forecasting beyond the

Boundaries of the Regional Model

2017 ITE Western District Annual Meeting

Made Possible Using Data Courtesy of NDOT

(formerly Parsons Brinckerhoff)2

• The difficulties with

forecasting at or beyond a

model’s boundaries

• Example: Garnet

Interchange

• Conclusions & Suggested

Approaches

• Questions & Answers

Topics Covered

The Garnet Interchange Today


• Models tend to be most accurate in

the regional center (most detailed

networks, most traffic counts,

smallest TAZs, etc.)

• But most development occurs

towards the urban fringe. Mis-match

between the forecasting needs and

the forecasting tool

• Problem not unique to Las Vegas;

happens everywhere

The Problems with Life on the Edge

Population Growth in RTC Model, 2013-to-2035


• The problems are even worse when going beyond the

boundaries of the modeled area:

• Developers land bank large areas without detailed plans

• Timeline dependent on market conditions; hard to predict

• Through traffic is a high percentage of total traffic, but it is

dependent on global factors you may not know much

about

The Problems with Life on the Edge

But work must go forward, even in the face of uncertainty


Example: Garnet Interchange

• Located at the edge of the RTC

model region (20 miles from

downtown)

• Being considered for a major

upgrade in support of development

at Apex Industrial Park

• Traffic forecasts needed as input

for civil design

GarnetInterchange

Apex Industrial

Park


Garnet Interchange: Traffic Flows

• Through Traffic

• Outlying Communities

• Apex Traffic

• All handled somewhat

abstractly in the

regional model

Utah

Central Nevada

Mesquite

Coyote Springs

Apex Industrial Park

MoapaGarnet

Interchange


The Great Recession, a Game-Changer

Change in U.S. Employment duringPost WWII Recessions

• The Great Recession was deeper and much, much longer than any previous post-WWII recessions

• Structural changes are taking place in the U.S. economy. Some of these changes are permanent. Things will not “go back to normal”; there is a new normal

• This will have long-lasting effects on development. Growth assumptions made before the recession must be re-examined and revised


Forecasting Through Traffic on I-15

• Pre-recession forecasts predicted rapid growth

• Instead, traffic declined by 20%

• The post-recession trendlinemay also be misleading since it includes a major one-off event

• Shows the need to base the forecast on changes in the underlying demand (GRP)

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Comparison of Trend Forecasts (Pre-Recession Study versus Recent Counts)

Recent Traffic Counts Current Fitted Formula 2008 Fitted Formula Pre-Recession Traffic Counts


Technique #1: Use Growth of Underlying

Demand Forecasting Through Traffic on I-15

Regression analysis found that 87% of the variation in I-15 traffic could be explained by

changes in Las Vegas GRP

Derived a fitted curve formula to match the data


Forecasting Through Traffic on I-15

Lower than pre-recession forecasts, but consistent with recent trends

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Through Traffic on I-15 North of Garnet IC

Pre-Recession Forecast Through Traffic (Forecast) Through Traffic (Actual)

Used the forecasts for future GRP from Population Forecasts: Long-Term Projections for Clark County, Nevada 2015-2050 to forecast the traffic going forward


Technique #2: Trip-Gen Rate * Population

Forecasting Traffic from Outlying Communities

• Checked various variable to see how closely they track actual traffic between towns & Las Vegas; None worked well

• Computed the population growth rate based on long-term average 0

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Pre-Recession Low Range

Mesquite Actual

Mesquite Forecast (Current)

• Computed the actual per-capita trip-gen rate for trips to/from Las Vegas (from ramp counts). Multiplied this by future population to estimate future trips


Forecasting Traffic from Coyote Springs

• Land banking for possible new town sometime in the future

• Local jobs, % retirees, etc. are unknowable

• Lacking better data, but distance & market similar to Mesquite, so assumed same rate of trip-making to Las Vegas as Mesquite

• Multiplied Mesquite trip-gen rate by population forecast for Coyote Springs to arrive at forecast. Forecast assumed a delayed build-out for Coyote Springs

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CS Master Traffic Study, 2002

Pre-Recession Study, 2010

Current Study


Technique #3: Site Details


• Location within site determines the traffic using Garnet Interchange

• Type of jobs, density within each site, sequence of development, etc. are unknown

• Faraday Future developing a factory and bringing in utilities

• Utilities installed to serve one site could spur developments on neighboring sites that could connect up

Traffic does not pass through Garnet

Interchange

Traffic doespass through

GarnetInterchange

GarnetInterchange


Forecasting Traffic for Apex Industrial Park

• Forecasts from Population Forecasts: Long-Term Projections for Clark County, Nevada 2015-2050 suggest anemic growth in transportation and warehousing jobs and actual reductions in manufacturing and utilities jobs over the study period

• Suggests that Apex is unlikely to build out during the study period (at least not with manufacturing jobs)

• Market trends suggest that warehousing may be a good fit for this site

• If significant employment develops, then some retail is likely to follow


Forecasting Traffic for


• Assumed that Faraday Future would create 4,500 industrial jobs as planned

• Assumed that blue triangle would take advantage of utilities to build warehousing (719 jobs) and retail (100 jobs)

• Trip-generation rates taken from ITE

• Concentrating development off US-93 is the worse case for Garnet Interchange design purposes

Site of Faraday Future

GarnetInterchange


Putting it All Together – Traffic at Garnet IC

• After the growth of each component of traffic component had been forecast individually, they were added together to produce the forecasts used for design purposes

• Forecasts were considerably lower than a pre-recession study, but seem more reasonable in light of current traffic and growth expectations

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Pre-Recession Forecast

Traffic on I-15 North of Garnet Interchange

Actual Forecasts

Assumed effect of internalization


Conclusions & Suggested Approaches

• When forecasting for developments at or near the edge, you are forced to rely on data sources other than the regional model.

• Depending on the situation and available data, more than one technique may be needed

• Large disruptive events (e.g. Great Recession) break previous patterns and force a re-evaluation of previous assumptions. May need to let go of earlier assumptions.

• To the extent possible, base your forecasts on changes in the underlying demand (GRP & population) rather than on plans. Remember: Approved plans show what is permissible, but the markets determine what will actually happen.


Questions & Answers

Don Hubbard, TE, AICP

Senior Technical Principal in Transportation Planning/ModelingWSP, Sacramento(916) 567-2555

[email protected]

Documents

Over the Edge - ITE Western District...• Land banking for possible new town sometime in the future • Local jobs, % retirees, etc. are unknowable • Lacking better data, but distance