This month, the focus of our downtown outreach is crosswalks. Here we will share information from a more technical engineering and landscape architectural viewpoint. Simply click on any topic or question below to jump to the content. Read some or read it all. And if you have questions, please ask.
You will notice that we use Pennsylvania’s Department of Transportation (PennDOT) as a reference point. Most of our downtown projects are in Pennsylvania but please be assured, as we are working in many states outside of Pennsylvania (including Maine, New Hampshire, Massachusetts, Maryland, Ohio, New York, Tennessee, and Virginia, to name a few!), we make it our business to be up-to-date and educated on the rules and regulations in all the cities, towns, municipalities, and boroughs where we work.
In Pennsylvania, PennDOT designates three basic crosswalks, type A, B, and C. These conform to the Manual of Uniform Traffic Control Devices (MUTCD) published by the Federal Highway Administration.
- Type A ”“ This crosswalk is designated by two parallel lines. Lines are 6” to 24” wide and are set a minimum of 6’ apart. This is the simplest and most commonly seen crosswalk.
- Type B ”“ Consists of the Type A parallel lines with the addition of 12” to 24” wide 45 ° diagonal lines.
- Type C ”“ Consists of the Type A parallel lines with the addition of 12” to 24” wide perpendicular lines. We sometimes call this the piano key design.
In addition PennDOT allows three standard decorative designs
- Type D ”“ Stamped asphalt ”˜courtyard’ pattern
- Type E ”“ Stamped asphalt ”˜herringbone’ pattern
- Type F ”“ Stamped asphalt ”˜offset brick’ pattern
Each decorative pattern must be accompanied by the basic 6” minimum white border. If you are planning to use other patterns and/or colors, you will need PennDOT approval.
PennDOT typically discourages anything that is not their standard detail. Townships, boroughs, and cities are generally more receptive to creativity in crosswalks.
Basic crosswalk striping is painted with reflective paint for economy. But this can lead to the need for frequent maintenance.
Better quality striping methods include hot liquid applied thermoplastic with reflective glass beads. Sheet applied markings are also available with glass beads imbedded. These are fused to the road surfaces using a heat source. This method is more durable but also involves a greater implementation cost.
At midblock crosswalks, advanced warning signs and pavement markings may be desirable, advisable, or required by governing agencies.
More advanced crosswalks may use overhead lights and pavement-embedded lights which are more costly to install and maintain. Flashing lights may be advisable where the driver may need additional advanced warning of pedestrian crosswalks. These are also frequently seen at school zone crossings.
PennDOT has been distributing Yield to Pedestrian signs to be placed on the centerline of roadways. The theory goes that they are more likely to be seen (and obeyed) by drivers than curbside signs. The signs may be placed at intersection crosswalks or midblock crosswalks.
What About Stamped Asphalt, Resin, and Pavers?
Stamped asphalt involves a process requiring the heating of existing asphalt surfaces to a plastic state. Then decorative templates are pressed into the hot asphalt using compaction equipment. Finally color is applied using a host of different methods.
The least expensive coloring method involves applying the color as a liquid. Thicker and more durable coatings are produced in sheets that are melted and pressed into the asphalt. This method is accepted by PennDOT.
Another application is a poured in place resin surface. This material is sold under the brand name AddaPrint, among others. This material is cold-applied at a ¾” thickness on existing pavement and then stamped with decorative patterns. Typically this requires milling of the paving to create a flush surface. One of the benefits is that aggregates can be embedded in the liquid to increase traction.
Pavers are generally smaller, segmented, cast or fired units used for paving. They are an option for decorative and durable crosswalks. Unit pavers can be a very durable installation provided a strong concrete edge and base detail is used to contain the pavers.
Unit pavers rely on interlocking pavers to disperse the force of rolling wheels. Consequently, selection of patterns is critical to maximize the interlocking feature. The herringbone pattern is one of the best for maximizing interlock.
Unit pavers are typically not acceptable on PennDOT roadways however they are used on non-PennDOT city and townships roads.
Some common varieties of pavers include:
Concrete unit pavers ”“ an economical choice among pavers
Typically a thicker paver is used for crosswalks as compared to those used in residential applications (+/- 3 inches). These pavers can be set in asphalt or sand beds on top of reinforced concrete slabs.
Clay brick pavers ”“ maximum durability
Clay brick pavers typically hold their color better and are more expensive than concrete pavers although the installation method is identical. Some cities have brick streets that have been in service for more than a century. Remember reading about Portsmouth, NH? (link to Portsmouth blog) safekeeping
Asphalt pavers ”“ something new
Asphalt pavers are not common nationwide, probably due to a limitation in the colors and patterns available. However, they are widely used in New York City and Europe.
Stone cobbles are perhaps the most durable of all paving products and also the most costly. Cobbles are commonly split from granite or basalt. Cobbles wear like iron and are readily recyclable. Cobbles are typically set in a sand setting bed on a gravel or concrete slab base. New Castle, DE benefits from the use of cobbles. (link to patina/New Caste blog) – patina
A Little about Bump-outs, Bulb-outs, and Curb Extensions
Bump-outs, bulb-outs, and curb extensions are three well used terms, all referring to the same thing. They are popular as a safety measures on urban streets.
The primary purpose is to allow cars and pedestrians to see each other better where parallel parking occurs. Other benefits may include:
- Providing additional room to create curb ramps for accessibility
- Narrowing the roadway and encouraging drivers to slow down
- Decreasing the time pedestrians are crossing in the roadway
Drawback of bump-outs include:
- Complicating street drainage by interrupting continuous curb lines. May require installation of more drainage structures
- Increasing traffic congestion by preventing right turn movements through parking lanes/shoulders
- Complicating efficient removal of snow along curb lines
Concerning Raised Pedestrian Walkways or Speed Tables
Speed tables can be an effective method of traffic calming on local streets. Benefits include:
- Raised tables allow improved accessibility for pedestrians since they eliminate curb ramps
- They are preferred by emergency services over speed humps because they are more gradual and less jarring to on a large emergency vehicle.
However, drawbacks include:
- Roadway drainage complications which may require additional drainage structures.
- Slowing of snowplowing operations. Snow plows tend to damage pavement surface that changes abruptly.
- Creation of a hindrance on collector streets for emergency services where speeds are higher.