Here are 2 ways to estimate capital costs for PRT:
- By the Numbers - Facts and figures below provide a high level of confidence in the LoopWorks' estimate of $15M/mile of one-way guideway.
- Visually - PRT is much smaller than traditional mass transit options. Like compact cars compared with luxury cars, PRT will be much less expensive than mass transit options. Click here for the visual presentation.
Capital Costs to Build Personal Rapid Transit (PRT)
This graph shows industry-accepted capital cost estimates for PRT systems under varying installation conditions and number of vehicles per kilometer (multiply by 1.5 for vehicles per mile). As one would expect, costs rise with installation difficulty and number of vehicles. LoopWorks' estimate of $15M/mile lies near the middle of the cost estimates.
A chart similar to the one above can be found on PDF page 54 of Mineta Transportation Institute's 2014 report: "AUTOMATED TRANSIT NETWORKS (ATN): A REVIEW OF THE STATE OF THE INDUSTRY AND PROSPECTS FOR THE FUTURE". Included in the report is this summary of costs:
"For medium-capacity applications, system and major civil costs of $10-$20 million per elevated one-way mile appear to be reasonable (Figure 33). This includes guideways, stations, vehicles, maintenance/storage facilities, control systems, etc., but it excludes external costs (utility relocations, right-of-way acquisition, special artwork, etc.). Kerr, James, and Craig in 2005 found that ATN infrastructure per mile costs about one-third of that for APM, and ATN stations cost about one-half of that for APM." [emphasis added]
At 30 mph, each PRT vehicle covers 88 feet every two seconds.
(5280 ft * 30)/hour ÷ 3600 sec/hour = 44 ft/sec
Only 60 vehicles will fully populate a mile of guideway.
5280 ft/mile ÷ 88 ft/vehicle = 60 vehicles/mile
The Economics section (pages 35 – 37) of the ITNS Business Plan estimates the cost of one vehicle including storage guideway at $88,326. If vehicle cost is rounded up to $100,000 each, it only costs $6M to populate a mile with cabs. (60 cabs/mile * $100,000 = $6M) While PRT miss the cost reductions of mass produced vehicles, they don't bear the costs of government-approved highway vehicles such as expensive batteries, complex steering and suspension, heavy gas motors, fuel tank/pump/injectors, radiator/water pump/hoses, transmission and drive train, crumple zones, ignition system, muffler, and catalytic converter.
Using ITNS' estimate, vehicles will represent - at most- 40% of PRT system cost. ($6M ÷ $15M = 40%)
How to Reduce Congestion and Save Energy offers this chart of system components and their relative cost. Their numbers include 42% for guideway (blue), 25% for vehicles (red). LoopWorks uses the ITNS design that minimizes the most expensive part of PRT - the guideways.
Comparing PRT and Airport APMs
PRT systems are a small-scale version of conventional Automated People Movers (APM) in use at many airports. This image shows the relative sizes of PRT and APM vehicles. While PRT cabs generally carry 4 or fewer passengers, APM vehicles carry 20 or more passengers.
Data available from over 100 APMs currently in use around the world informed the ATRA document Infrastructure Cost Comparisons for PRT and APM:
Guideway and station costs have been analysed for APM and PRT systems. Comparison between these results leads to the conclusion that on average; PRT infrastructure can be provided for a third the cost per mile of equivalent APM infrastructure, and PRT stations for at least half the cost of an APM station. [emphasis added]
The PRT/APM cost analysis above relied upon the ULTra PRT system by using results from the construction of the test track and from an in-depth costing exercise. Because the ITNS design used by LoopWorks has substantially smaller guideway and cabs, costs will likely be even lower than 1/3 of APM costs.
This bar chart shows that cost estimates for transit infrastructure largely depend upon vehicle weight and, by extension, support structure weight. As shown in yellow, costs rise relative to vehicle weight. (Chart is from page 4 of "IS THERE A CASE FOR HIGH SPEED, HIGH CAPACITY ATN/PRT SYSTEMS?") Clearly smaller infrastructure costs less than larger infrastructure.
Variability of PRT System Costs
According to "Personal Rapid Transit for Microsoft and Bellevue" by Jerry Schneider and Steve Raney:
It is possible to produce PRT at a low delivered cost of $10M per mile, as well as a high $40M per mile. A model whereby engineers have financial incentives to keep costs down will be more advantageous than that of a traditional "cost plus" manufacturer that passes on cost overruns to taxpayers.
Such a wide range of estimates - $10M/mile to $40M/mile - stems from the many variables available to PRT designers as shown in this chart.
Contributions to the Development of Personal Rapid Transit by J. Edward Anderson (page 211) notes that distributing the people-carrying capacity of vehicles over the guideway in many small units instead of a few large conventional vehicles, the weight per unit of length of the guideway can be reduced by a factor of at least 20. By choosing an inexpensive guideway design and small cabs as LoopWorks has done, overall costs are dramatically reduced. Costs may be further reduced if Bosch Captive Column technology is employed in the guideway design.
This chart comes from page 2 of a 2004 report by TRANSEK Consultants for the project entitled European Demonstration of Innovative City Transport (EDICT). The report compares costs between Bus, PRT, LRT and AGS (Automated Guideway Systems or "APM" in the US). Each estimate includes the total investment costs for guideway, vehicles and stations. Bars in blueish are Stockholm systems, in green are PRT systems, and in red/brown are other systems.
The three Stockholm LRT systems cost around 15-20 M Euro per track-kilometer (24-32M€/mile). A summary of 22 Automated Guided Systems in the US have an average cost of 17M Euro per track-km (27M€/mile). All three PRT systems show a lower investment cost than the LRT systems. An average of the three PRT systems yields an investment cost of 6M€ per track-kilometer (9.6M€/mile). The LoopWorks design is derived from the Taxi 2000/ITNS design, so its cost most closely approximates what the Milpitas PRT system will cost.
If we extract the Taxi 2000 cost of 3.4 M€ per kilometer (5.5M€/mile),
use the 2004 date-of-publication conversion rate of 1.2 dollars per Euro ($6.6M/mile),
and factor in a 36.6% cumulative inflation rate from 2004 to 2020,
current costs are estimated to be only $9.0M/mile
-- far less than the $15M/mile estimate used by LoopWorks for business purposes.
Other Data Points
A PRT cost estimate was developed by members of the Sky Loop Committee in Cincinnati. Last revised in 2001, it included a table of capital costs as part of the financial analysis section for the 12.84-mile proposed PRT system. That table provides cost estimates for various components of a PRT system with Taxi 2000/ITNS attributes, including 55 vehicles per mile of guideway. Their 2001 estimate of $5.5M total capital costs per mile was adjusted to $8.5M/mile ($109/12.84 miles) in A Rebuttal to the Central Area Loop Study Draft Final Report. (That report includes a brief overview of many aspects of the technology.) That $8.5M/mile estimate rises to $12.4M/mile in 2020 dollars after adjusting for inflation. Again, the actual cost may be even less than LoopWorks' $15M/mile estimate.
- This 2015 news article says the SkyTran flavor of PRT infrastructure costs $13M per mile ($8M per kilometer).
- This 2016 news article says the 2getthere flavor of PRT infrastructure costs $24M for 2.5 miles, or $10M/mile. The Modutram flavor of PRT infrastructure costs $16M for 2.5 miles, or $6.4M/mile.
- In 2016, two companies bid on the 2.5 miles of one-way guideway needed at the Greenville-Spartanburg Airport. At the estimated construction cost of under (and well-under) $25M, companies are now bidding PRT systems at $10M/mile rather than the $15M/mile used for Milpitas estimates.
- In 2017, responding to requests of the of the Santa Cruz County Regional Transportation Commission for public input about its Draft UCS study, Santa Cruz PRT, Inc. submitted a proposal that uses a $15M/mile estimate for guideway cost (see page 5, BUDGET).
- In the 2019 business plan of ITNS (page 36), is an estimate of $12M for system cost per mile.
- In March, 2017, a paper prepared for the Greenville County Economic Development Corporation by PRT Consulting included the following paragraph from their earlier December 2016 report entitled A NEW TRANSPORTATION PARADIGM THAT FACILITATES HIGH QUALITY CITY LIVING (page 11 of the PDF) "ATN systems cost far less than other fixed-guideway modes like light rail. One mile of one-way guideway complete with vehicles and stations ranges in cost from about $10 million to $30 million. Lower cost applications are at grade and have lower capacity while elevated, high capacity applications cost more."
Comparing LRT, GRT and PRT
These cost comparisons between transit modes comes from page 10 of A Light Rail, Group Rapid Transit, Personal Rapid Transit Comparison. The existing West Rail Line light rail transit (LRT) deployment in Denver, USA is compared with the results that could reasonably have been expected had the deployment been accomplished using group rapid transit (GRT) or personal rapid transit (PRT) technology that is currently commercially available. The projected 54 miles of PRT for $671M works out to $12.4M/mile.
Visual Presentation: PRT is smaller; smaller costs less.
Less Infrastructure Stuff = Less Cost
These images of the monorail at the 1967 World's Fair in Montreal show the relative size of the monorail along with the tight turning radii and flexible routing of such small-scaled system. Due to size of the vehicles (12 passengers rather than 4), the monorail is physically bigger than the LoopWorks' guideway, and it requires supports that are both larger and more frequent. (These screenshots come from an 8-minute film about the Fair.)
Comparing Transit Guideway/Track Sizes
This image shows the relative sizes of (1) Disney Monorail guideway, (2) elevated LRT railbed, and (3) PRT guideway. The small print (click image to enlarge) shows that the (1) Disney Monorail uses 5,800 cu. yards of concrete and 1200 tons of steel per mile, while the (2) elevated LRT railbed uses 28,000 cu. yards of concrete and 2900 tons of steel per mile. The elevated LRT railbed built through Milpitas cost about $120M/mile. As you can see, (3) TriTrack, a minimalist type of PRT, uses far less concrete and steel - and therefore costs far less to build. Although the LoopWorks guideway will be about twice the size of TriTrack guideway, it will still use far fewer materials.
This image from ATRA's document Infrastructure Cost Comparisons for PRT and APM compares infrastructure for an ULTra PRT guideway, the Las Vegas monorail, the Sydney monorail, and the Kuala Lumpur LRT. The ULTra PRT guideway is 3 times the size and weight of LoopWorks PRT guideway.
Not shown in these drawings is a pedestrian footbridge which must accommodate pedestrian loads of around 500kg/m2 -- much more than the 200kg/m2 load of a continuous string of PRT vehicles. The footbridge at the Milpitas BART station cost $14M, a testament to the cost of heavy infrastructure.
This graph shows relative costs of 5 configurations of guideway. Type 2, supported, is the type used by LoopWorks and generally costs the least to build. As you can see, spans of about 30 meters (90 feet) are most cost-effective. Just 60 posts would be needed for 1 mile of guideway.