Editing Light rail (section)

==Comparison to road traffic==
[[File:Kaohsiung LRT Circular Line at Gate of Kaohsiung Port 20180621.jpg|thumb|[[Circular light rail]] in front of the Gate of [[Kaohsiung]], [[Taiwan]]]]
[[File:A Crystal Mover LRT train on boarding.jpg|thumb|A [[Crystal Mover]] [[Automated people mover|APM]] train on boarding]]

===Comparison with high capacity roads===
One line of light rail (requires 7.6 m, 25' right of way) has a theoretical capacity of up to 8 times more than one 3.7 m (12 foot) lane on a freeway, excluding busses, during peak times. Roads have ultimate capacity limits that can be determined by [[Traffic engineering (transportation)|traffic engineering]], and usually experience a chaotic breakdown inflow and a dramatic drop in speed (a [[traffic jam]]) if they exceed about 2,000 vehicles per hour per lane (each car roughly [[two-second rule (road)|two seconds]] behind another).<ref>Matt Lorenz and [[Lily Elefteriadou]] (2000) [http://onlinepubs.trb.org/onlinepubs/circulars/EC018/08_52.pdf ''A Probabilistic Approach to Defining Freeway Capacity and Breakdown''] (PDF), Transportation Research Board.</ref> Since most people who drive to work or on business trips do so alone, studies show that the average car occupancy on many roads carrying commuters is only about 1.5 people per car during the high-demand [[rush hour]] periods of the day.<ref>{{cite web|title=Highlights of the 2001 National Household Travel Survey: A-15 Vehicle Occupancy Per Vehicle Mile by Time of Day and Weekend Status|url=http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/highlights_of_the_2001_national_household_travel_survey/html/table_a15.html|publisher=US Department of Transportation|access-date=24 February 2016|archive-date=28 June 2017|archive-url=https://web.archive.org/web/20170628142015/https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/highlights_of_the_2001_national_household_travel_survey/html/table_a15.html|url-status=dead}}</ref>
This combination of factors limits roads carrying only automobile commuters to a maximum observed capacity of about 3,000 passengers per hour per lane. The problem can be mitigated by introducing high-occupancy vehicle ([[High-occupancy vehicle lane|HOV]]) lanes and [[ride-sharing]] programs, but in most cases, policymakers have chosen to add more lanes to the roads, despite a small risk that in unfavorable situations an extension of the road network might lead to increased travel times ([[Downs–Thomson paradox]], [[Braess's paradox]]).<ref>https://homepage.rub.de/Dietrich.Braess/Paradox-BNW.pdf (1968) end of chapter 4 retrieved 2023/02/27</ref><ref>{{Cite web|title=Ontario Expanding Highway 401 in Cambridge|url=https://news.ontario.ca/en/release/33297/ontario-expanding-highway-401-in-cambridge|access-date=2 December 2021|website=news.ontario.ca}}</ref><ref>{{Cite web|title=Ontario is finally widening Highway 401 through the GTA|url=https://www.blogto.com/city/2019/04/ontario-widening-highway-401/|access-date=2 December 2021|website=www.blogto.com|language=en}}</ref>

By contrast, light rail vehicles can travel in multi-car trains carrying a theoretical ridership up to 20,000 passengers per hour in much narrower [[Right-of-way (transportation)|rights-of-way]], not much more than two car lanes wide for a [[double track]] system.<ref>Tom Parkinson and Ian Fisher (1996) [http://nrc40.nas.edu/news/blurb_detail.asp?id=2603 ''Rail Transit Capacity''] {{webarchive|url=https://web.archive.org/web/20090111162103/http://nrc40.nas.edu/news/blurb_detail.asp?id=2603 |date=11 January 2009 }}, Transportation Research Board.</ref> They can often be run through [[tramway tracks|existing city streets and parks]], or placed in the [[median (road)|medians of roads]]. If [[Street running train|run in streets]], trains are usually limited by city block lengths to about four 180-passenger vehicles (720 passengers). Operating on two-minute headways using traffic signal progression, a well-designed two-track system can handle up to 30 trains per hour per track, achieving peak rates of over 20,000 passengers per hour in each direction. More advanced systems with separate rights-of-way using [[Moving block|moving block signaling]] can exceed 25,000 passengers per hour per track.<ref>[http://www.trb.org/news/blurb_detail.asp?id=2326 ''Transit Capacity and Quality of Service Manual''], Transportation Research Board.</ref>

===Practical considerations===
Most light rail systems in the United States are limited by demand rather than capacity (by and large, most American LRT systems carry fewer than 4,000 persons per hour per direction), but Boston's and San Francisco's light rail lines carry 9,600 and 13,100 passengers per hour per track during rush hour.<ref name="Hanson 2004">{{cite book
  | last1 = Hanson
  | first1 = Susan
  | last2 = Giuliano
  | first2 = Genevieve
  | title = The geography of urban transportation
  | publisher = Guilford Press
  | year = 2004
  | isbn = 1-59385-055-7}}</ref> Elsewhere in North America, the [[Calgary]] [[C-Train]] and [[Monterrey Metro]] have higher light rail ridership than Boston or San Francisco. Systems outside North America often have much higher passenger volumes. The [[Manila Light Rail Transit System]] is one of the highest capacity ones, having been upgraded in a series of expansions to handle 40,000 passengers per hour per direction, and having carried as many as 582,989 passengers in a single day on its [[Manila Light Rail Transit System Line 1|Line 1]].<ref>{{cite web|url=http://www.lrta.gov.ph/press_release/press_release_090112_25yrRecordHigh.htm |title=LRT-1 sets 25-year high record ridership |publisher=Manila Light Rail Transit Authority |date=12 January 2009 |access-date=14 March 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090326064515/http://www.lrta.gov.ph/press_release/press_release_090112_25yrRecordHigh.htm |archive-date=26 March 2009 }}
</ref> It achieves this volume by running four-car trains with a capacity of up to 1,350 passengers each at a frequency of up to 30 trains per hour. However, the Manila light rail system has full grade separation and as a result, has many of the operating characteristics of a metro system rather than a light rail system. A capacity of 1,350 passengers per train is more similar to the heavy rail than light rail.

====Bus rapid transit====
[[Bus rapid transit]] (BRT) is an alternative to LRT and many planning studies undertake a comparison of each mode when considering appropriate investments in transit corridor development. BRT systems can exhibit a more diverse range of design characteristics than LRT, depending on the demand and constraints that exist, and BRT using dedicated lanes can have a theoretical capacity of over 30,000 passengers per hour per direction (for example, the [[Guangzhou Bus Rapid Transit]] system operates up to 350 buses per hour per direction). For the effective operation of a bus or BRT system, buses must have priority at traffic lights and have their dedicated lanes, especially as bus frequencies exceed 30 buses per hour per direction. The higher theoretical of BRT relates to the ability of buses to travel closer to each other than rail vehicles and their ability to overtake each other at designated locations allowing express services to bypass those that have stopped at stations. However, to achieve capacities this high, BRT station footprints need to be significantly larger than a typical LRT station. In terms of cost of operation, each bus vehicle requires a single driver, whereas a light rail train may have three to four cars of much larger capacity in one train under the control of one driver, or no driver at all in fully automated systems, increasing the labor costs of BRT systems compared to LRT systems. BRT systems are also usually less fuel-efficient as they use non-electrified vehicles.

An irregular ride experience, including sudden breaking and acceleration, results in a lower ride quality for passengers compared to LRT.<ref>{{cite book |title=The Urban Rail Development Handbook |publisher=PPIAF |page=73 |url=https://www.ppiaf.org/documents/5532 |access-date=9 April 2025}}</ref>

====Capacity comparison====
The peak passenger capacity per lane per hour depends on which types of vehicles are allowed on the roads. Typically roadways have 1,900 passenger cars per lane per hour (pcplph).<ref>{{cite book|title=NCHRP Report 599: Default Values for Highway Capacity and Level of Service Analyses|year = 2008|url=http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_599.pdf#page=13|publisher=NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM| doi=10.17226/22061 | isbn=978-0-309-43229-0 }}</ref> If only cars are allowed, the capacity will be less and will not increase when the traffic volume increases.

When there is a bus driving on this route, the capacity of the lane will be higher and will increase when the traffic level increases. And because the capacity of a light rail system is higher than that of a bus, there will be even more capacity when there is a combination of cars and light rail. Table 3 shows an example of peak passenger capacity.

{| class="wikitable"
|-
!   !! Car !! Car + bus !! Car + light rail
|-
| Low volume || 900|| 1,650|| 2,250
|-
| Medium volume|| 900|| 2,350|| 3,250
|-
| High volume|| 900|| 3,400|| 4,600
|-
| colspan="4" style="text-align: center;" | '''Source:''' Edson & Tennyson, 2003{{Full citation needed|date=January 2020}}
|}