Over the Edge. Forecasting beyond the Boundaries of the Regional Model

Transcription

1 Over the Edge Forecasting beyond the Boundaries of the Regional Model 2017 ITE Western District Annual Meeting Made Possible Using Data Courtesy of NDOT

2 Topics Covered The difficulties with forecasting at or beyond a model s boundaries Example: Garnet Interchange Conclusions & Suggested Approaches Questions & Answers The Garnet Interchange Today 2

3 The Problems with Life on the Edge 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 Population Growth in RTC Model, 2013-to

4 The Problems with Life on the Edge 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 But work must go forward, even in the face of uncertainty 4

5 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 Garnet Interchange Apex Industrial Park 5

6 Garnet Interchange: Traffic Flows Through Traffic Outlying Communities Apex Traffic All handled somewhat abstractly in the regional model Central Nevada Coyote Springs Garnet Interchange Moapa Apex Industrial Park Mesquite Utah 6

7 The Great Recession, a Game-Changer 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 reexamined and revised Change in U.S. Employment during Post WWII Recessions 7

8 Forecasting Through Traffic on I-15 Pre-recession forecasts predicted rapid growth Instead, traffic declined by 20% The post-recession trendline may 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) Comparison of Trend Forecasts (Pre-Recession Study versus Recent Counts) 50,000 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5, Recent Traffic Counts Current Fitted Formula 2008 Fitted Formula Pre-Recession Traffic Counts 8

9 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 9

10 Forecasting Through Traffic on I-15 Used the forecasts for future GRP from Population Forecasts: Long-Term Projections for Clark County, Nevada to forecast the traffic going forward 40,000 Through Traffic on I-15 North of Garnet IC Pre-Recession Forecast Through Traffic (Forecast) Through Traffic (Actual) 35,000 30,000 25,000 20,000 Lower than pre-recession forecasts, but consistent with recent trends 15,000 10,000 5,

11 Persons 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 100,000 90,000 80,000 70,000 60,000 50,000 40,000 30,000 20,000 Population of Mesquite Pre-Recession High Range Pre-Recession Low Range Mesquite Actual Mesquite Forecast (Current) 10,000 rate based on long-term average 0 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 11

12 Population of Coyote Springs Forecasting Traffic from Coyote Springs Land banking for possible new town sometime in the future 120, ,000 Local jobs, % retirees, etc. are unknowable 80,000 60,000 CS Master Traffic Study, 2002 Pre-Recession Study, 2010 Lacking better data, but distance & market similar to Mesquite, so assumed same rate of trip-making to Las Vegas as Mesquite 40,000 20,000 0 Current Study Multiplied Mesquite trip-gen rate by population forecast for Coyote Springs to arrive at forecast. Forecast assumed a delayed build-out for Coyote Springs 12

13 Technique #3: Site Details Apex Industrial Park 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 pass through Garnet Interchange Traffic does not pass through Garnet Interchange Garnet Interchange 13

14 Forecasting Traffic for Apex Industrial Park Forecasts from Population Forecasts: Long-Term Projections for Clark County, Nevada 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 14

15 Forecasting Traffic for Apex Industrial Park 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 Garnet Interchange 15

16 Daily Vehicles on I-15 North of Garnet IC 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 100,000 90,000 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0 Actual Pre-Recession Forecast Forecasts Assumed effect of internalization Traffic on I-15 North of Garnet Interchange 16

17 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. 17

18 Questions & Answers Don Hubbard, TE, AICP Senior Technical Principal in Transportation Planning/Modeling WSP, Sacramento (916)