Performance Measure

The buffer index represents the extra time (buffer) most travelers add to their average travel time when planning trips. This is the extra time between the average travel time and near-worst case travel time (95th percentile). The buffer index is stated as a percentage of the average travel time. Average buffer index or buffer time can be calculated using miles traveled as a weighting factor. Buffer time = 95th percentile travel time (min) – average travel time (min).

Associated Objectives

Decrease the buffer index for (specific travel routes) by X percent over the next Y years.
Decrease the average buffer index for (multiple routes or trips) by X percent over Y years.
Reduce the average buffer time needed to arrive on-time for 95 percent of trips on (specified routes) by X minutes over Y years.

Service Packages that Support the Performance Measure

VS05-Curve Speed Warning
TM04-Connected Vehicle Traffic Signal System
VS08-Queue Warning
VS10-Restricted Lane Warnings
VS09-Reduced Speed Zone Warning / Lane Closure
TM21-Speed Harmonization
TI07-In-Vehicle Signage
TM03-Traffic Signal Control
TM05-Traffic Metering
TM06-Traffic Information Dissemination
TM08-Traffic Incident Management System
TM20-Variable Speed Limits
TM22-Dynamic Lane Management and Shoulder Use
MC04-Winter Maintenance
MC06-Work Zone Management
TI01-Broadcast Traveler Information
TI02-Personalized Traveler Information
TI03-En-Route Guidance

Associated Goals

Improve the efficiency of the surface transportation system
Improve the resiliency and reliability of the surface transportation system

Planning Factors

G. Promote efficient system management and operation;
I. Improve the resiliency and reliability of the transportation system and reduce or mitigate stormwater impacts of surface transportation;


Planning for Operations Desk Reference