New Jersey Smart Growth Gateway: Solutions

TDM Strategies to Increase Vehicle Occupancy

TDM strategies support smart growth's goals by:

Reducing the number of vehicles on the road
Providing an accessible, affordable, equitable range of transportation choices
Encouraging energy efficiency
Using transportation and land resources more efficiently

TDM strategies traditionally have been directed toward commute travel and peak period congestion, but are more recently being utilized to help address other, non-recurring types of congestion as well. Commuter directed strategies are typically employer-based, whereas area-wide TDM programs are more typically implemented by government based agencies.

TDM encompasses travel alternatives and strategies to support them. Because it involves behavioral change, TDM often relies on incentives or disincentives. Research shows that because many TDM strategies are complementary, they work best as part of overall larger transportation planning effort or comprehensive program.

Demand management strategies fall into four main categories:

Strategies to increase vehicle occupancy

Ridesharing
Ridesharing encompasses carpooling and vanpooling, when two or more people share a ride in a private car or van. Carpools generally accommodate two to six passengers in an automobile; vanpools usually accommodate between seven and fifteen passengers in a van. Commutes between 10 and 20 one-way miles are best suited for carpooling, while vanpooling is generally more cost effective when used for commutes over 20 miles.

Carpooling is a common alternative to driving alone, perhaps because it offers many of the same conveniences and creature features as single-occupancy driving. In 2000, according to the United States Census Bureau, 10.6% of all work trips in New Jersey were made by carpooling (that's slightly less than the national average of 12.2%).

Ridesharing is an inexpensive and potentially effective means of reducing peak period congestion. It can increase the efficiency of the transportation network simply by carrying more people in fewer vehicles. Anthony Downs, in his book Stuck in Traffic (1992, The Brookings Institution) shows that ridesharing is the most effective means of reducing peak period congestion. Using data from 1983 showing that single occupant automobiles accounted for 34% of all morning peak period trips, he calculated the reductions in peak period trips that could be achieved by ridesharing.

% of drivers switching to a 2-person carpool	% of peak period trips reduced
10	3.4
15	5.1
20	6.8

In New Jersey, free rideshare matching services are provided by eight Transportation Management Associations (TMAs), under contract with the New Jersey Department of Transportation. Commuters can call the TMA serving the county in which they work and receive a match list with the names of others that have similar commute patterns. Rideshare matching programs are more effective at the work end than at the home-end of the trip. (Implementing Effective Travel Demand Measures, ITE, 1993). They are particularly well suited for suburban employment centers that are not well served by transit.

Incentives offered by employers to encourage ridesharing include allocating the most conveniently located parking spaces to vanpools and carpools; free rideshare matching services, an emergency ride home program for employees who engage in an alternate commute mode, providing fleet vehicles for company travel during the day, providing on-site amenities to reduce the need for personal travel at lunch and during the day; Other effective strategies include appointing an on-site coordinator and eliminating free parking.

Vanpooling is eligible for federal and state tax incentives that are not available to carpoolers. Employers who offer their employees commuter benefits are eligible for tax credits and pay less federal withholding tax. NJ TRANSIT, through the State's TMAs, offers a subsidy program for vanpools that operate in areas not served by public transit.

Assistance on implementing rideshare programs and strategies to support them is available through the state's TMAs. Most New Jersey TMAs provide the following services to employers and commuters:

Free rideshare matching
Emergency ride home programs
Transit information and assistance
On-site events and promotions

Learn More:
TMA Council of New Jersey
New Jersey Dept. of Transportation
NJ Commuter
NJ Commuter's "Share the Road"

HOV Lanes
High-occupancy vehicle (HOV) lanes can be an effective way to encourage travelers to use higher occupancy modes of travel such as carpools, vanpools or transit. By dedicating road lanes for exclusive use by these types of vehicles, users can realize reduced and more predictable travel times, which are powerful incentives to encourage mode shift.

Depending on how they are physically constructed (either constructing a new lane, or taking an existing lane and turning it into an HOV lane) and operated (e.g., full time dedicated or reversible, contra-flow lane) HOV lanes can either support or combat sprawl.

HOV lanes that are supported by other TDM actions such as transit enhancements, high level support for rideshare information services, and conveniently located park-and-ride lots can be effective in reducing traffic without inducing single-occupancy vehicle (SOV) travel.

However, without careful planning, HOV lanes can become victims of their own success and contribute to sprawl. An inherent conundrum of HOV facilities is that if they are highly used, they offer less time-savings and predictability for occupants of high occupant vehicles. At the same time, they make the general purpose lanes less congested. If they are underutilized and revert to general purpose lanes, they add capacity to the highway system, which, in the long run, can cause sprawl and worsen traffic. Support and coordination among various stakeholders is critical for an HOV facility to succeed in both reducing congestion and supporting smart growth principles.