The Proper Stop Spacing of Rapid Transit Lines
This article examines how close together stops on rapid transit lines should be. For information about bus stop spacing, please see here .
The question of how many stops to provide along a rapid transit line is one that still has no definitive answer. Some transit systems aim for a stop about every mile, while others prefer stops every 1/2 mile. The basic trade-off is that the more stops you have the more geographically convenient you make your service for the passengers but the less chronographically convenient you will make your service, as each additional added stop decreases the operating speed and thus increases the amount of time needed to go between any two points along the line.
Historically, rapid transit lines were placed very close together. Stations along the Paris Metro, London Underground, and the New York and Boston subways are very rarely more than 1/2 mile apart, and frequently as close together as 1/4 mile. More recently, conventional wisdom has dictated wider stop spacings. Los Angeles Metro policy dictates that there should be a rail station approximately every mile, although this policy has sometimes been overruled in the past and is likely to be overruled again in the future. BART in the San Francisco Bay area has segments where stations can be as long as five miles apart. The Chicago Transit Authority is currently examining whether some of the stations along the Red Line should be closed because they are too close to the adjacent stations.
Recent light rail lines under construction support the contention that there has yet to be an industry consensus on the proper spacing of rapid transit lines. For example, Seattle seems to be following Metro's spacing guideline of 1 mile between stations: their Central Line has 12 stations for 13.9 miles of track and their University Line will have 2 stations for 3.1 miles of track when it is complete. On the other hand, the proposed Honolulu line has 36 planned stations for about 20 miles of track and the two lines in the Minneapolis - St. Paul region have 19 stations for 12 miles (the Hiawatha Line, currently open) and 18 stations for 11 miles (the Central Line, currently under construction). It is important to note that the Central Line has more stations than originally proposed: additional stations were added after representatives of the low-income heavily minority community through which it will travel complained they had to suffer all the construction-related hassle while receiving none of the line's eventual benefits.
What are the advantages and disadvantages of a rapid transit stop spacing of 1/2 mile versus 1 mile? Of course, one disadvantage of additional stops is that additional stops add cost. An underground rapid transit station can easily cost $150 million, which is one reason why Seattle's University Link only has two stations: an additional station, at First Hill, was eliminated due to cost.
Apart from cost, the question goes back to the original trade-off between geographic and chronologic convenience. Additional stations will mean additional customers will be within convenient walking distance of the station; on the other hand, additional stations will mean existing customers - those already on the train - will have their journey time lengthened by as much as 1 minute for each additional station the train has to stop at.
Considering that the rail lines that have been opened in the United States are far from at capacity, it seems as though the pendulum should swing on the side of additional stations to attract additional customers. Note that you might disagree with me on this: you may comment that the Los Angeles Red Line is quite crowded, especially during the peak period. While true, the Red Line corridor is equipped to allow thirty trains per hour, and there are only twelve trains per hour currently operating along the portion of the corridor that is shared with the Purple Line.
Another factor weighing in favor of more frequent rail stations is land use. Assuming that supportive land use regulations are enacted, a rail station can eventually lead to a more pedestrian-friendly sustainable neighborhood. But studies that have examined the effect of rail stations on property values (read more about this topic here ) have found that the impact of a rail station on local land use only extends to about 1/4 mile radius from the station. If stations are located every 1/2 mile then the entire corridor can be under the influence of the rail station, but if stations are located every mile then there will be a 1/2 mile "no man's land" that is not within easy access of a station. For a good illustration of this effect travel to Toronto and conduct a walking tour of the Sheppard subway line. Mini-downtowns around most of the stations quickly give way to dreary auto-oriented commercial outside of the station's sphere of influence.
A final factor promoting a 1/2 mile stop spacing is the effect that the rail line will have on the currently existing bus service. Operating rail service is expensive, and the money has to come from somewhere. Frequently this money comes at the expense of bus service. In fact, Salt Lake City is proposing to pay for the operation of their new light rail lines by canceling all bus service on Sunday. Having more frequent rapid transit stops can enable the transit system to pay for the operation by canceling the bus route that operates along the rapid transit corridor rather than reducing service on bus routes in other areas. Toronto is a great example of a city that does this: the majority of Bloor and Yonge Streets, which the subway lines travel underneath, only have bus service late at night after the subway stops operating. Average stop spacing of 1 mile will likely require local bus service still be operated along the rapid transit corridor to serve the "no man's land".
Overall, the opportunity to attract additional customers, shape sustainable land use patterns, and take advantage of transit efficiencies all point to having light rail stops every 1/2 mile instead of every mile. The feeling of speed will make the incremental addition in journey times additional stops will add hardly noticeable, especially to passengers who are accustomed to making the same journey in a slow bus.