5.5 Railroad Grade Separation

Reduce idling times to lower emissions and improved traffic system efficiency.

Description

Railroad grade separations remove periodic traffic delays on major roadways by raising or lowering either the rail line or the roadway and permitting more efficient flow of traffic at major rail crossings.

This strategy can be a large-scale project and may require high costs in right-of-way and construction. Close cooperation must be gained with the affected railroad company. The system-wide air quality benefits are low and difficult to predict. However, these programs should provide measurable reductions in localized CO and hydrocarbon emissions. Delay time is eliminated at the rail grade separation.

Application

Arterials with delays caused by at-grade rail crossings.

$\text{Daily Emission Reduction (grams/day)} = A \times B$

$A = t_{H,C} / t_{H} \times V$

The number of vehicles affected by rail crossing delays

$B = t_{C} / 2 \times \mathit{EF}_{I}$

The average idling emissions resulting from affected traffic idling at the closed crossing (assumed to be half of the average time the roadway is closed per train crossing)

Variables	(Unit)	Definitions
$\mathit{EF}_{I}$	(grams/hour)	Idling emission factor (NO_X, VOC, PM, or CO)
$t_{C}$	(hours/crossing)	Average amount of time rail crossing is closed due to train crossing
$t_{H}$	(hour)	Duration of analysis period
$t_{H,C}$		Hours per analysis period roadway is closed due to train crossing
$V$		Bi-directional arterial volume for analysis period

Source: Texas A&M Transportation Institute