MNTRC Newsletter Vol. 20, Issue 3: Winter 2013

Study examines three ways to reduce greenhouse gas


Robert B. Noland, PhD, Director, Voorhees Transportation Center

Cranford (NJ) Crossing

Figure 1: Scenario GHG Emissions

Rutgers News – Greenhouse gas (GHG) emissions must be reduced 50-80% by 2050 to limit global temperature increase to 2⁰C. It is challenging to achieve reductions of this magnitude in the transportation sector, requiring a multitude of policies and technology options. We are providing here three transportation demand management (TDM) scenarios: changes in the perceived price of travel, land use intensification, and increases in transit. This study uses elasticity estimates derived using an activity-based travel demand model for the state of California. It broadly represents the US; and it is the first analysis of this type to estimate policy impacts using an activity-based model. Argonne National Laboratory’s VISION model is used to quantify the GHG impacts from policy scenarios, providing a life-cycle GHG forecast for the road transportation sector out to 2040 under the most current forecasts for changes in vehicle fleets and fuels.

Scenario Arc Elasticity
LDV MDV HDV
Land Use Transit-Oriented Development leads to 10% increase in population and job density -0.31 -0.46 -0.01
Transit Increased investment and new starts doubles transit service -0.02 0.00 0.00
Pricing VMT pricing leads to 50 to 100% increase in per mile driving costs -0.30 -0.03 -0.05

Policy Scenario Descriptions

Our team’s scenario analysis suggests that, relative to 2000 levels, only the vehicle miles traveled (VMT) pricing scenarios provide significant reductions in emissions from the 2040 baseline. Increasing the marginal cost of driving by 50% decreases emissions 8-13% relative to the 2040 baseline, or 23-27% relative to 2000 levels.

Some vehicles respond better to pricing policies.

Doubling the marginal cost results in emissions levels lower than the 2040 baseline by 16-27%, a 29-38% reduction from 2000 levels. The land use and transit scenario provides a maximum reduction of about 4.7% from the baseline and a 20% reduction from 2000 levels. The policy for the transit scenario was quite aggressive, doubling the amount of service provided. While the elasticity for increased transit service (-0.02) is within the range of other studies, a doubling of transit service provides little headway towards even the 50% reduction target.

Graph of greenhouse gas reduction.

Figure 2: LDV Emission for Individual Scenario

It’s no surprise that the light-duty vehicle (LDV) fleet is much more responsive to our TDM policies than are freight and long distance commercial trucks, which have limited options for increasing load-factors or shifting modes. Under medium-response to the pricing policy, the LDV fleet is able to reduce emissions by very nearly 50% during the period 2040 when pricing is doubled (Figure 2). These results suggest that deeper reductions in emissions may be possible through pricing than have been found in other studies that estimated much lower distance-based pricing charges.

GHG reductions will be difficult to meet.

Technological progress could be made on a variety of fronts, including increased use of electric drive and fuel cell vehicles, further increases in fuel economy, increased use of natural gas in vehicles, and increasing the amount of renewable bio-mass based diesel and ethanol blended into fuels.

Graph of additional reductions needed.

Figure 3: Additional per-mile reductions needed to meet GHG targets.

Rather than looking at the possibilities for each such option, one way to look at how much technological progress is necessary is to examine the per-mile emissions reductions necessary to meet climate policy targets.

Figure 3 illustrates the additional percent per-mile efficiency necessary to meet a 50% target, relative to 2000 for light-, medium-, and heavy-duty vehicles, and all fleet vehicles for each policy option analyzed. These results are sector-specific but show the difficulty with meeting targets for GHG reductions from surface transportation.

Life-cycle reductions of 50% from the 2000 baseline will require aggressive technology policies supplemented with pricing policies. The latter will likely also require supportive land use and transit measures to mitigate the impact of increased travel costs.