Distance between parking signs – how far should you go?

While posting appropriate Parking or No Parking Signs on roads, in private driveways, offices, malls, business complex etc., sign installers are often faced with questions like- How many signs should be installed- How much is too much?  How far apart should two signs be erected? How tall a Parking Sign should be in order to be clearly visible to the traffic and not obstruct or hit the oncoming vehicles?

Although all of the above questions are important to be considered while posting signs at any facility, public road etc., the one question that often confuses sign installers frequently is the distance between subsequent Parking Signs.

Appropriate distance between signs ensures that they are visible to the moving traffic and are not missed out while entering or exiting a road, parking lot etc.

Every state identifies a specific distance that should be maintained between two signs.Pennsylvania, for example, mandates 250 foot spacing between No Parking Signs in rural areas. New York requires a maximum of 200 ft spacing between Parking Signs. In Philadelphia, one Parking Sign per block is all that is required to regulate vehicle parking.

Apart from the state-specific regulations, some factors that determine the spacing between two signs are-

• Legibility Distance- Measuring legibility distance (using a rule of thumb that each 1 inch sign lettering height equals 50 inches of legibility) helps installing subsequent signs in an area. The idea is that an average motorist should be able to view and understand the information displayed on the sign and has enough time to react to it.
• Speed- The speed of the vehicle also determines the distance between two signs. Viewer Reaction Time (VRT) for vehicles traveling with a speed less than 35 miles per hour in a 2-3 lane environment is 8 seconds. While the VRT for vehicles traveling over 35 miles/hour in a 4-5 lane environment, is 10 seconds. The same logic applies here. Motorists traveling at different speeds should be able to react to the signs posted on the way. Hence sign spacing for different vehicles such as cars, trucks, bikes etc. would also be different.

These factors may be considered in ideal circumstances and with appropriate instruments to measure distances and speed. In practice, however, signs especially No Parking Signs are posted every 25’ to 75’ of distance with most property owners choosing a 30’ distance between signs.