Thursday, April 22, 2010

Speed Humps - Winchester Street, Brookline, MA

Speed Humps - Winchester Street, Brookline, MA

Submitted by Despina Chrysochos



Winchester Street is a local street in Brookline, off Beacon Street. It starts at the intersection with Beacon Street, runs for 0.6 miles, holds 280 street numbers and ends perpendicularly at Brainerd Street. The area is mostly residential made up by houses, few apartment buildings and a couple of senior houses. Winchester Street has a relatively low volume of traffic compared with other local streets in the area. There is a large number of pedestrians on the sidewalks, people hanging out at their front yard and some bicycles travelling on both directional flows.

As far as the structure of the roadway is concerned, Winchester Street consists of one lane in each direction. There is a parking lane that runs next to the Northwestern Bound lane. There is a bicycle lane that runs by the Southeastern Bound. Winchester is geographically almost a straight street. It consists of only one very small horizontal turn with a very large radius, and it has a very stable and small vertical grade.


A long clear zone for the drivers is created due to most of the street being straight who tend to speed up a lot. Therefore, the city of Brookline wanted to enforce traffic calming at Winchester Street. By implementing traffic calming, the street gets lower vehicles’ speeds, increased safety on the roadway and improvement in quality of life. Hence, two speed humps were installed, which aim in reducing traffic speeds, decreasing traffic volumes and minimizing accidents.



Winchester Street, now, has two speed humps, and a choker towards the end of the street, in order to lower the cars’ traveling speeds. The street is designed for a travel speed of 30 miles/hour and there are also signs indicating the speed limit. The drivers, though, feel safe by driving on a straight roadway, they speed up and they exceed the 30 miles/hour often. When the car approaches the hump, the car is supposed to slow down, decelerate and bring the car down to a travel speed of 20 miles/hour or even lower, and there are signs indicating a lower speed, too. The reason for slowing down at a hump is necessary is that the impact to the car as well as to the passenger is very intense when going over it with a high speed. The impact could even harm the car’s engine as well as “shake” vigorously the passengers inside the car. Two speed humps aim to be more effective than one since they keep the travel speed between the two humps slow and do not give the driver the adequate distance and time to accelerate. The street gives enough warning to the driver to keep his speed low by several signs. As the car enters Winchester Street, the driver reads a bright yellow sign that indicates a speed limit 30mph. Then as the car approaches the speed hump, he reads another bright yellow sign that says “Raised Slow Crossing, 300 ft Ahead”, then about 100 feet forward he reads a third one that says
“RAISED CAUTION CROSSING, 20mph” and finally when he gets to the hump there are two very bright yellow signs on both sides of the street indicating the crosswalk. Two warning signs ahead of the hump, at a distance of 100 feet, and two signs on both sides of the street of the crosswalk, can be effective. Between the two humps there is another sign that indicates a travel speed of 25 miles/hour, to keep the vehicles at relatively safer speed.


Another feature that the speed humps on Winchester Street have, that makes them more visible and enforce deceleration is the eight white horizontal lines ahead of the hump. These lines are perpendicular to the flow of traffic in order to make the driver realize that there is a speed hump ahead and therefore there is a need to slow down. Furthermore, there are two large white arrows on the first inclined part of the hump that point out the raising surface, which for once again, warn the driver to reduce speed.



The whole design for achieving traffic calm is effective to only a portion of drivers that tend to be loyal when driving. The combination of two speed humps, a number of signs along the street and the marks on the asphalt contribute to reducing the traffic speeds but not as much as it is needed.


The reason is that the first speed hump is located outside the house with an address of 64 Winchester Street. The second one is located outside the house with an address of 164 Winchester Street. The distance between them is almost 1050 feet. This distance gives the vehicles enough space and time to increase their speed and go beyond the limit. As a result, when they enter Winchester Street from Beacon Street, they face a long, straight and clear roadway and accelerate to 35 – 38 miles/hour. When they get to the hump, they drop their speed down to 25 miles/hour and then accelerate again as they pass the hump to 30 – 32 miles/hour until they get to the next hump. Therefore, the speed reduction between the two humps is not effective.



The travel speeds are kept high even when cars go over the humps because the humps are smooth. The humps have a low upgrade in the beginning, which is not that alarming to the car and the driver. Then, they have a flat surface for about four feet and finally a low downgrade which brings the vehicle back to the roadway’s surface smoothly. This makes the drivers to go over the humps with 25 miles/hour and more, resulting in a non-efficient the speed reduction.

This could be improved by adding two more humps between the already existing ones. In this scenario, the vehicles’ speeds will be kept down to 20 – 23 miles/hour between the humps. If the humps have a distance of 300 feet between them, it will be more effective in decreasing the vehicles’ travel speed. Another improvement that should be done is to make the initial upgrade of the hump steeper so that the change will be more sudden and bothering to driving and the drivers will be enforced to decelerate to 15 – 20 miles/hour on the hump. The travel speed on the hump is particularly important since the two existing humps on Winchester Street are also used as crosswalks. This improvement will be more efficient to traffic calming since it will actually reduce the travel speeds, decrease the travel volumes and provide more safety to pedestrians and the neighborhood.

The picture below shows the idea of steeper humps that are closer together.
picture taken in Nicosia, Cyprus.

4 comments:

  1. The Cyprus photos of dual humps close together is great. The analysis is a little confused -- at first it says the spacing is effective, then it says it's too great. I have observed traffic there too often to believe cars pass over the humps at 25 mph (10 mph is more like it). There's also confusion about the desired speed -- it certainly isn't 30 mph -- but good recognition that the straightaway encourages speeds closer to 40 mph which needed to be dealt with.

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  2. Nice blog, really I impress for your blog. I got more information about Speed humps . This type of speed humps are very urgent for all drivers.

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