--- title: "On-street vs off-street parking; kerb parking geometry" subject: "Transportation Engineering II" chapter: 1 key: "semester_7/transportation_engineering_ii:parking-onstreet-offstreet-comparison-geometry" source: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/parking-onstreet-offstreet-comparison-geometry site: BCT Engineering --- # On-street vs off-street parking; kerb parking geometry Transportation Engineering II · Chapter 1: Traffic Engineering - Asked in: 2070 Chaitra (old course), 6 marks - Video: [Parking Study || Types of Parking || Kerb Parking || On-Street Parking || Off-Street Parking || T...](https://www.youtube.com/watch?v=yUDSclL1BT0) — ENGINEER MIND - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/parking-onstreet-offstreet-comparison-geometry - Whole chapter: https://www.bctengineer.com/md/semester_7/transportation_engineering_ii/chapter-1 ## Question Compare on-street and off-street parking. Draw neat sketches showing parallel and angle kerb (on-street) parking geometry. ## Short answer On-street parking is cheap, convenient but reduces road capacity and safety; off-street is expensive, secure, high capacity, no traffic impact. Parallel parking uses ~5.5–6.0 m kerb per car, least width; angle parking (30°,45°,60°,90°) reduces kerb length per car but needs wider bay and aisle. ## Answer #### Comparison of on-street and off-street parking | Aspect | On-street | Off-street | |---|---|---| | Location | On the carriageway edge | In lots, garages, basements | | Cost | Very low (markings, signs, meters) | High (land, construction, staff) | | Convenience | Very close to the destination | Slightly further to walk | | Effect on traffic | Reduces road capacity and safety | No effect on road capacity | | Capacity | Small | Large, especially multi-level | | Safety and security | Lower; risk of theft/damage | Better supervision and security | | Control | Hard; often illegal parking | Easy; gates, tickets, fees | | Pedestrian effect | Obstructs footpath | Protects footpath | #### Parallel parking geometry Bay size for a car: about 5.0 m long x 2.5 m wide, and with the gap needed to manoeuvre in and out each car uses about 5.5-6.0 m of kerb (trucks need about 7.5 m x 3.75 m, buses more). The car is parked parallel to the kerb, which needs the least road width but gives the fewest bays. ```text carriageway -------------------------------------- <- traffic -> ======================================== kerb line _____5.0 m_____ _____5.0 m_____ | car | gap | car | 2.0-2.5 m |_________| |_________| ======================================== kerb ``` #### Angle parking geometry (30, 45, 60, 90 degrees) The vehicle is parked at an angle to the kerb, front end first (or reversed in). A larger angle gives more cars per length of kerb but needs a wider strip of road and a wider aisle. ```text 45 degree parking carriageway <- traffic -> ====================================== \ \ \ \ \ \ stall width along kerb \__\__\__\__\__\ = 2.5 / sin(angle) ====================================== kerb ``` | Angle to kerb | Kerb length per car | Depth of the bay from kerb | |---|---|---| | 0 (parallel) | 5.5-6.0 m | 2.0-2.5 m | | 30 degrees | about 5.0 m | about 4.7 m | | 45 degrees | about 3.5 m | about 5.3 m | | 60 degrees | about 2.9 m | about 5.6 m | | 90 degrees | about 2.5 m | about 5.0 m | (For a car 2.5 m wide x 5.0 m long: kerb length per car = 2.5/sin(angle); bay depth = 5.0 sin(angle) + 2.5 cos(angle).) The aisle width kept for manoeuvring is largest for 90-degree parking (about 6 m). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is a main drawback of on-street parking? A. Very high cost B. It reduces road capacity and safety C. It needs multi-level structures D. It is too far from destinations Answer: B. Parked cars on the carriageway edge reduce capacity and safety, but cost is low and access is close. (Key point: On-street effect on traffic) 2. Which is true of off-street parking compared with on-street? A. Cheaper to provide B. Closer to the destination always C. Better supervision and security, no effect on road capacity D. Always illegal parking Answer: C. Lots and garages are controlled with gates and fees, and they do not use the carriageway, but they cost more. (Key point: Off-street advantages) 3. As the parking angle to the kerb increases, what happens? A. Fewer cars per length but narrower strip B. More cars per length of kerb but a wider strip and aisle needed C. No change in kerb length per car D. Parallel parking becomes the same as 90 degrees Answer: B. Larger angles pack more cars along the kerb but need greater road width. (Key point: Effect of parking angle) 4. For a 2.5 m wide car, kerb length per car at 45 degrees = 2.5/sin(angle) is about: A. 2.5 m B. 5.0 m C. 3.5 m D. 2.9 m Answer: C. 2.5/sin 45 = 2.5/0.707 = 3.5 m. (Key point: Kerb length per car) ## Related in Transportation Engineering II - [Parking importance, illegal parking, on/off-street types](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aparking-importance-illegal-onstreet-offstreet) — Transportation Engineering II, chapter 1 - [Street light spacing method and parking types](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Astreet-light-spacing-parking-types) — Transportation Engineering II, chapter 1 ## Related in other subjects - [Aeroplane angle of attack and take-off power](https://www.bctengineer.com/question.md?key=semester_3%2Ffluid_mechanics%3Aaeroplane-angle-of-attack-power) — Fluid Mechanics, chapter 9 - [Street inlets: curb vs gutter inlet](https://www.bctengineer.com/question.md?key=semester_6%2Fsanitary_engineering%3Astreet-inlets-curb-gutter) — Sanitary Engineering, chapter 4 - [HRC fuse quartz sand, cut-off, vs Kit-Kat](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_power_distribution_and_illumination%3Ahrc-quartz-sand-kitkat) — Industrial Power Distribution and Illumination, chapter 3 - [On-site vs off-site sanitation and fecal-oral route](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Aonsite-offsite-fecal-oral) — Technology, Environment and Society, chapter 5