12 Transportation · 12.1 Transportation planning
12.1.1 Urban road hierarchy, road cross-section elements, IRC design standards and traffic signs
Urban roads are graded from expressways and arterials (mobility) down to collectors and local streets (access), and each class gets its own right of way, design speed and cross-section, set by IRC codes and, in Maharashtra, by the UDCPR road-width tables.
- MPSC ATP
- Standard level
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Core facts
- Urban road hierarchy (IRC:86-1983): Arterial → Sub-arterial → Collector → Local street. Expressways sit above arterials as a separate, access-controlled class.
- Recommended right of way (ROW), IRC:86:
- Arterial 50–60 m
- Sub-arterial 30–40 m
- Collector 20–30 m
- Local street 10–20 m
- Design speeds, IRC:86: arterial 80, sub-arterial 60, collector 50, local 30 km/h.
- Lane width: 3.5 m per lane on multi-lane roads; two-lane carriageway 7.0 m (7.5 m with raised kerbs); single-lane carriageway 3.75 m on rural roads (IRC:73-1980; IRC:86 takes 3.5 m for urban roads).
- Roadway (formation width) = carriageway + shoulders. ROW = the whole land width acquired for the road.
- Footpath: minimum clear width 1.8 m (IRC:103-2012).
- Road plans of India: Nagpur 1943 (five-fold classification, star-and-grid pattern); Bombay 1961–81 (32 km per 100 sq km); Lucknow 1981–2001 (82 km per 100 sq km).
- Traffic signs (IRC:67): circular = mandatory/regulatory; triangular with red border = cautionary (warning); rectangular = informatory. STOP is octagonal; GIVE WAY is an inverted triangle.
Explained
Function of each urban road class
| Class | Main job | Access to plots | Typical spacing of junctions |
|---|---|---|---|
| Arterial | Through traffic across the city | Restricted | Widely spaced, often signalised |
| Sub-arterial | Links arterials, carries some through traffic | Partly restricted | Closer than arterial |
| Collector | Collects traffic from local streets to arterials | Allowed | Frequent |
| Local street | Access to plots | Full | Very frequent |
Mobility falls and access rises as you go down the hierarchy. A good network connects each class only to the class next above or below it.
Nagpur Road Plan five-fold classification (non-urban roads)
- National Highways (NH): main highways across the country, linking state capitals and ports.
- State Highways (SH): main trunk roads of a State, linking district headquarters.
- Major District Roads (MDR): connect areas of production and markets with each other and with NH, SH and railways.
- Other District Roads (ODR): serve rural areas and link them to markets, taluka headquarters and MDRs.
- Village Roads (VR): connect villages to each other and to the nearest higher road.
Cross-section elements
| Element | What it is |
|---|---|
| Carriageway | Paved width used by moving vehicles |
| Shoulder | Strip beside the carriageway for stopped vehicles, emergency use and lateral support |
| Roadway / formation width | Carriageway + shoulders (+ median, if any) |
| Median | Divider between opposite directions |
| Kerb | Raised edge between carriageway and footpath or median |
| Right of way | Whole land width, including future widening |
- Kerb types: low or mountable (about 100 mm), semi-barrier (about 150 mm), barrier (about 200 mm).
- Camber (cross slope for drainage): about 1.7–2.0% for cement concrete and high-type bituminous surfaces; 2.5–3.0% for WBM and gravel; 3.0–4.0% for earth roads. Rougher surfaces need steeper camber. Heavy rainfall areas take the upper value.
Worked example (ROW from elements) Two-lane carriageway 7.0 m + one parking lane 2.5 m + footpaths 2 × 1.8 m + utility strips 2 × 1.5 m = 7.0 + 2.5 + 3.6 + 3.0 = 16.1 m.
UDCPR road widths (Maharashtra)
- Reg 3.3.2, Table 3A – internal roads in a residential layout:
- length up to 150 m: 9.0 m
- above 150 m up to 300 m: 12.0 m
- above 300 m: 15.0 m
- Table 3B (non-residential): 12.0 m, 15.0 m, 18.0 m or more for the same lengths.
- Table 3C (group housing): 7.5 m (to 150 m), 9.0 m (to 300 m), 12.0 m (to 600 m), 15.0 m (above 600 m).
- Reg 3.3.8 – ROW of classified roads, unless the DP, RP or TP scheme says otherwise (applies to ADAs, metropolitan and special planning authorities, new towns and RP areas):
| Road | ROW | Remark |
|---|---|---|
| National Highway | 60 m | Includes 12 m service roads on both sides |
| State Highway | 45 m | Includes 9 m service roads on both sides |
| Major District Road | 24 m | No service road |
| Other District Road | 18 m | No service road |
| Village Road | 15 m | No service road |
- Plots along highways take access from service roads; highway amenities such as fuel stations may have direct access (Reg 3.3.8(a)).
- Classified roads passing through municipal areas are treated as city roads (Reg 3.1.6).
Traffic signs (IRC:67)
| Group | Shape and colour | Examples |
|---|---|---|
| Mandatory / regulatory | Circle; red border for prohibitory, blue disc for compulsory | No entry, speed limit, compulsory left |
| Cautionary / warning | Triangle, apex up, red border | School ahead, narrow bridge, sharp bend |
| Informatory | Rectangle | Direction, parking, hospital, fuel |
STOP (red octagon) and GIVE WAY (inverted triangle) are regulatory signs with special shapes so drivers recognise them from the back or in poor light.
Common traps
- ✗ "The hierarchy is arterial, collector, sub-arterial, local." ✓ Arterial → sub-arterial → collector → local.
- ✗ "Roadway means the right of way." ✓ Roadway = carriageway + shoulders; ROW is the whole land width.
- ✗ "IRC lane width is 3.75 m on multi-lane roads." ✓ 3.5 m per lane; 3.75 m is the single-lane carriageway of rural roads (IRC:73).
- ✗ "Triangular red-bordered signs are mandatory." ✓ They are cautionary (warning); circular signs are mandatory.
- ✗ "The Nagpur Road Plan target was 82 km per 100 sq km." ✓ 82 is the Lucknow plan; Bombay was 32.
- ✗ "UDCPR NH width is 60 m excluding service roads." ✓ 60 m including 12 m service roads on both sides.
Quick revision
- Arterial, sub-arterial, collector, local (IRC:86-1983); expressway above.
- ROW: 50–60, 30–40, 20–30, 10–20 m.
- Design speed: 80, 60, 50, 30 km/h.
- Lane 3.5 m; two-lane 7.0 m; single lane 3.75 m (rural).
- Roadway = carriageway + shoulders.
- Footpath at least 1.8 m (IRC:103-2012).
- Nagpur 1943 five-fold; Bombay 32; Lucknow 82 km/100 sq km.
- IRC:67: circle mandatory, triangle warning, rectangle informatory.
- UDCPR Table 3A: 9 / 12 / 15 m for up to 150 / 300 / above 300 m.
- UDCPR 3.3.8: NH 60, SH 45, MDR 24, ODR 18, VR 15 m.
Go deeper: Deeper, Mains writing (beyond what MPSC ATP usually asks)
Deeper Advanced
- Definitions in UDCPR Reg 1.3.
- Building line (22): the line up to which the plinth of a building next to a street may lawfully extend, including lines fixed by a scheme, DP or RP.
- Control line (32): a line on either side of a highway, beyond the building line, fixed by the Highway Authority.
- Road / street line (108): the line defining the side limit of a road.
- Road width (109): the whole space within the road boundaries, measured at right angles to its course.
- Junction rounding (UDCPR Reg 3.3.12): at right-angle junctions, the tangent length of the rounding is half the width of the road across the tangent. Buildings set back from the rounded line.
- Cul-de-sacs (Reg 3.3.10): allowed only in residential areas and on straight roads, normally up to 150 m and at most 275 m with an extra turning space at 150 m; turning space at least 81 sq m, no side under 9 m.
- Stopping sight distance = lag distance + braking distance = vt + v²/(2gf), with reaction time t = 2.5 s as adopted by IRC. It governs the design of curves and junction sight triangles.
- Why the 1.8 m footpath. It lets two wheelchair users pass and is the clear width after removing poles, trees and vending zones. Wider footpaths are needed in commercial streets and near transit.
- Road density targets rose plan by plan: Nagpur aimed at about 16 km per 100 sq km within its 20-year period, Bombay at 32, Lucknow at 82 by 2001. The Bombay plan also proposed about 1,600 km of expressways.
- Complete streets. Modern Indian street guidelines treat the ROW as space for people first: continuous footpaths, cycle tracks, bus stops, vending zones and utilities, with carriageway width fixed last.
Mains writing Mains writing
- Frame: a city's road hierarchy decides whether traffic flows or chokes; when local streets carry through traffic, both safety and mobility suffer.
- Analysis points:
- Indian cities often have arterials with direct plot access and frequent openings, which cuts capacity.
- DP road widths are frequently not acquired in time, so built roads fall short of the ROW.
- Most of the ROW is often given to vehicles, though most trips are on foot, by cycle or bus.
- Way forward: protect hierarchy in the DP (service roads, access control on arterials), acquire ROW through TDR or TP schemes, and design complete streets.
- Example: a 30 m sub-arterial can carry a four-lane divided carriageway with 2 m footpaths, cycle tracks and a bus bay, instead of six cramped lanes.
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