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In a typical benefit-cost analysis, the value of travel time is calculated separately for various transportation modes (car, truck, bus, airplane), and trip purposes (which may include on-the-clock business travel, commuting to work, or personal travel) and conditions (congested, uncongested, comfortable, uncomfortable). Light trucks (vans, SUVs, and small pickup trucks) are generally classified with cars, which together are called automobiles or light duty vehicles. Regardless of the mode or trip purpose, the total value of time for vehicle occupants (driver and passengers) or freight is calculated as the average value per person, or per cargo ton, times the average vehicle occupancy (persons per vehicle or cargo tons per vehicle). Some specific factors that affect travel time unit costs are summarized below.
 

On-the-Clock Travel

"On the clock" travel refers to trips conducted by workers during the work day, as part of their jobs. Many on-the-clock trips are made by truck drivers, but some are also taken in cars, vans, or light trucks used to deliver packages, provide repair services, or travel to and from meetings. Since the costs of excess worker time are borne by businesses, there is a consensus that the value of travel time includes the value of workers' wage and fringe/overhead costs. The US Dept. of Transportation recommends using $21.20/hour for on-the-clock business travel (values in year 2000 dollars) (US DOT 1997). 

In some cases, business travelers are passengers rather than drivers, and so can perform productive work while traveling, for example, working on a bus, train or airplane. Transport Canada has adopted the practice of reducing the value of time savings for business travel by 25% under such conditions. In the US, this adjustment is generally not made, as a worker's ability to do work while riding in a car is limited.
 

Commute Travel

In most regional travel demand forecasting and simulation models, "commute trips" refer to peak-period commuting and is distinguished from non-work (personal) travel. The value of time for commuting trips is usually defined as a fraction of the wage rate. The US Department of Transportation currently recommends using a value of 50% of the average wage rate of $21.20/hour, which comes to $10.60/hour (values in year 2000 dollars) for commuting travel time (US DOT 1997). 

Commuting trips also tend to be more schedule-sensitive than personal travel, and hence there is a need to consider the costs of travel time variability under congested road conditions. Based on a survey in California, Small (1997) found that commuters have a strong aversion to unpredictable travel times under congested conditions, so that a minute of time savings under congested conditions is valued at 2.5 times that of an uncongested minute of travel time savings. A study by Cohen and Southworth (1999) refined this multiplier down to the range of 1.4 to 2.3. An earlier study by Waters (1992) concluded that a 1.3 to 2.0 mark-up factor is appropriate, depending on the level of congestion. In addition, separate studies of toll roads also show that peak period commuters make trade-offs between time and cost, in which they value their time at 1.4 to 1.8 times the normal value of time (see Sullivan, 2000). Litman (2009) recommends adjusting drivers' travel time costs to reflect the additional stress of driving under congested conditions, so unit time value are calculated as 50% of wages under level-of-service (LOS) A-C, but increase to 67% at LOS D, 84% at LOS E and 100% at LOS F. Passengers' travel time unit costs (cents per minute or dollars per hour) do not increase in this way, although congestion does tend to increase their total time and unreliability costs.


Personal Travel

Non-work trips include travel for shopping, personal business, social, and recreational purposes. Various regional transportation studies commonly assign a value for personal trips ranging from one-third to one-half of the average wage rate, though a higher fraction can be justified for long-distance trips. (For instance, the San Francisco Bay Area Metropolitan Transportation Commission model assumes 32% of the wage rate for shopping trips as compared to 46% of the wage rate for commuting trips.). Studies in the UK also show evidence that shopping trips can have a lower time value than commuting trips (Mackie 2003). However, the US Dept. of Transportation currently recommends using $10.60/hour (50% of the wage rate, valued in year 2000 dollars) for local personal travel, the same value as for commuting trips (US DOT 1997). The higher recommended value for intercity personal travel is $14.80/hour (70% of the wage rate).


Bus and Rail Transit Travel

Travel time for public transportation vehicles is valued as the sum of (1) the value of time for the professional driver (and conductors or other staff, if applicable), and (2) the value of time for passengers. Driver and staff time is calculated as the value of "on-the-clock" travel times the number of staff persons per vehicle. Passenger time may be calculated as any blend of the work-trip value of time and the non-work value of time, multiplied by the number of passengers per vehicle. (More conservative studies merely use 50% of the average wage rate, or $10.60/hour).

Sometimes, a separate time value is set for out-of-vehicle time, which includes time spent walking to and waiting at the transit stop. Since this may include some time spent standing around and being exposed to warm, cold, or rainy weather, the value of out-of-vehicle time may be set at a rate higher than the value of in-vehicle time (Small 1992). The US DOT (1997) recommends using 100% of the wage rate for time spent walking and waiting and 50% of the wage rate for time spent in transit vehicles. The UK Dept. for Transport (2001) also adopts a value for out-of-vehicle time that is double the in-vehicle time value. However, Cal-B/C uses 50% of the wage rate for all transit travel time.

Transit travel time unit costs can vary depending on travel conditions, with significantly higher values if walking, waiting and travel conditions are uncomfortable (crowded, dirty, too hot or cold, insecure, etc.) (Li 3003). Waiting time unit costs tend to decline if passengers have accurate real time bus and train arrival information, so they know how many minutes they must wait (Dziekan and Kotterhoff 2007). Litman (2007 and 2008) recommends adjusting travel time unit costs based on transit transit travel level-of-service (LOS), with significantly higher cost values for LOS D through F.


Medium & Heavy Truck Travel

Medium and heavy truck travel is generally considered "on-the-clock" business travel. If the truck is empty or carrying cargo that is not time-sensitive, then the value of time is essentially the average labor cost for professional truck drivers and any accompanying loading staff (including wage and fringe costs). The US Dept. of Transportation recommends using $18.10 as the wage rate for truck drivers (year 2000). However, some urban toll and congestion studies indicate that heavy-duty truck drivers value their time closer to $20-25 per hour. The Bureau of Labor Statistics found the US average hourly wage for heavy truck drivers as of year 2000 was $15.78. Adding 25% fringe costs raises the total cost of truck driver time to $19.73/hour (year 2000 dollars). FHWA's Highway Economic Requirements System (HERS, a benefit/cost system for highways) adopts a value of $21.95/hour for truck drivers.

Cargo can also have a time value. In the aggregate it is based on the interest costs of the value of the cargo, though in reality this tends to be trivial. More important is the potentially substantial value of time for the portion of goods considered time sensitive. This is defined as the portion of truck deliveries in which the cargo user (i.e., the shipper or recipient) bears excess costs of late pickup or delivery. These excess costs apply largely to construction and technology-based manufacturing and include the following categories:

  • User product spoilage — e.g., concrete/cement arriving outside of its useful life
  • Missed delivery window — pickup or delivery trips that arrive after the gate or loading dock is closed for the day (extending delivery time by a day or requiring re-delivery costs)
  • Late delivery — causing recipients to incur additional cargo-related costs associated with overtime pay at the loading dock and/or additional just-in-time processing cost penalties.

Research on the time value for cargo varies in its conclusions, depending on the nature of the cargo and industry, though there is a consensus that the value is not trivial. Updates to FHWA's HERS adds a value of inventory carrying cost alone, at $1.78/hour. A Montana benefit/cost analysis system developed by Cambridge Systematics and Economic Development Research Group (2004) adds an additional $2 to $28/hour for user costs of additional cargo delay. A 1997 study by the Texas Transportation Institute uses a truck time value of $45/hour, representing $25/hour on top of the standard USDOT value of driver time alone. A study by Levinson (2003) found a value of $49.42/hour for commercial vehicle operators in Minnesota. A study by DeJong (2000) found a range of values from $36-48/hour. A similar range of values was found by Waters (1995). At the high end, a survey of freight carriers by Small et al (1999) found values of freight transit time in the range of $144-$193/ hour, and costs of schedule delays of $371/hour. Additional case studies of the large value of "just-in-time" processing and scheduling benefits (sometimes exceeding $100/hour) are shown in reports of NCHRP 2-18.


Rail Freight Travel

Rail freight trips are valued similarly to truck trips: the value of "on-the-clock" time for all train staff plus the value of cargo time. However, the cargo of freight trains is much less likely to be time-sensitive. In addition, many rail freight trips involve loading and unloading time associated with intermodal transfers between trucks and rail cars. Thus train arrival and departure delays commonly also trigger accompanying truck time delays, which should be added to the total cost of delay.


Airplane Travel

Airplane trips can include both passenger travel, cargo travel, and mixed passenger/cargo travel (in which cargo is carried in the belly of passenger aircraft). In general, passenger air travel delay is calculated much like bus/rail transit trips: as the sum of "on-the-clock" time for aviation staff (aircraft pilots, flight attendants and ground crew) plus the value of time for all passengers. Since air travelers typically have higher income levels and are paying a premium for fast travel compared to ground transportation alternatives, it is generally accepted that there should be a higher time value for air travelers. Research has generally confirmed that air travelers tend to have a high percentage of professionals with time-sensitive schedules and travellers with limited time schedules, which would make their time more valuable.

The US Dept. of Transportation recommends using $23.30 for personal air travel, $40.10 for intercity personal travel and $28.60 as a blended average (values in year 2000 dollars). FAA guidelines defining the value of time for aircraft crew varies depending on the type of aircraft, because staffing levels vary among aircraft types. The total crew time for a Boeing 737, one of the more common types of aircraft in use at the time the guidelines were set, is valued at $737/hour as of 1997.
 
There is currently an Airport Cooperative Research Program project (ACRP 03-19) that is exploring the use of benefit-cost analysis for airport capital investment decisions.  The project will provide updated information on passenger value of time.  Information about the project project can be found here.

Non-Motorized Travel

Walking and cycling travel time unit costs vary significantly depending on conditions and preferences (Mackie, et al. 2003). Where conditions are unfavorable, travel time costs are high, but under favorable conditions costs are low or even negative: time spent walking or cycling is considered a benefit rather than a cost (Litman 2009). Many people value walking or cycling for enjoyment and exercise (it can reduce the need to spend special time exercising), and so will choose these modes even if they take longer than driving. Because walking and cycling are inexpensive travel modes, their effective speed (travel time plus time spent earning money to pay for transport) is often faster than driving (Tranter 2004). These factors are highly variable. A person may one day prefer walking and another day prefer driving. If people have high quality walk and cycling conditions they can choose the mode they consider best overall, taking into account all benefits and costs.

Summary 

Travel time costs are highly variable, including a small portion of travel with very high time values, to a significant portion of travel with little or no cost, since travelers enjoy the experience and would pay nothing to reduce it. High-time-value travel includes commercial travel, urgent personal trips, travel under uncomfortable or congested conditions, unexpected delays. Below are some general guidance for quantifying travel time unit costs.Commercial (paid) travel costs include driver wages and benefits, and the time value of vehicles and cargo. This type of travel has the greatest impacts on economic productivity.

    • Personal travel time is usually estimated at 25% to 50% of prevailing wages, but varies by factors such as type of trip, traveler and conditions. Most travel time valuation studies focus on commute travel and so do not necessarily reflect travel time unit costs for other kinds of trips, such as personal errands and recreational travel.
    • Travel time unit costs tend to increase with variability and arrival uncertainly, and are particularly high for unexpected delays during activities with strict schedules such as business travel and commuting.
    • Travel time unit costs tend to increase with income, and are lower for children and unemployed people (put differently, employed people are often willing to pay more for travel time savings).
    • The first few minutes of a trip often has minimal time cost since people generally seem to enjoy a certain amount of daily travel, but unit costs usually increase if trips exceed about 20 minutes duration or total personal travel exceeds about 90 daily minutes.
    • Some travel time has a low cost or positive value because people enjoy the experience, including recreational travel and errands that involve social activities.
    • Under pleasant conditions walking, cycling and waiting can have low or positive value, but under unpleasant conditions (walking along a busy highway or waiting for a bus in an area that seems dirty and dangerous), costs are two or three times higher than in-vehicle time.
    • Travel needs and preferences vary. For example, some people place a higher cost on time spent driving while others place a higher cost on transit travel. 


The table below summarizes a framework developed by Litman (2009) for adjusting travel time values to reflect travel conditions as measured by level-of-service values, which can be calculated using methods described in the new Highway Capacity Manual (TRB 2010) and other sources (VTPI 2010).

Potential Travel Time Values Relative to Prevailing Wages (Litman 2009)

Category

LOS A-C

LOS D

LOS E

LOS F

 

Waiting

 

 

 

 

 

 

Good

Average

Poor

Commercial vehicle driver

120%

137%

154%

170%

 

170%

 

Comm. vehicle passenger

120%

132%

144%

155%

 

155%

 

City bus driver

156%

156%

156%

156%

 

156%

 

Personal vehicle driver

50%

67%

84%

100%

 

100%

 

Adult car passenger

35%

47%

58%

70%

 

70%

 

Adult transit passenger – seated

35%

47%

58%

70%

35%

50%

125%

Adult transit passenger – standing

50%

67%

83%

100%

50%

70%

175%

Child (<16 years) – seated

25%

33%

42%

50%

25%

50%

125%

Child (<16 years) – standing

35%

46%

60%

66%

50%

70%

175%

Pedestrians and cyclists

50%

67%

84%

100%

50%

100%

200%

Transit Transfer Premium

 

 

 

 

5-min.

10-min.

15-min.

This summarizes recommended travel time values, based on Waters (1992) expanded to include public transit and non-motorized travel. These are default values that should be calibrated and adjusted to reflect specific conditions and the preferences of affected groups.


Sources

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